Electronic Observing Aid
MARS member Craig MacDougal came across an interesting snail mail that other members might like to review. It concerns an electronic device to assist those who record video of their observing sessions. It is a box that inserts a time display into the video signal using a GPS device (not included) as its time source. It would be good for occultations, eclipses and the like. Craig scanned both sides of the brochure and place them as JPEG files on his web space.
Here is page 1:
http://mysite.verizon.net/macdouc/osd0001.jpg
…And here is page 2:
http://mysite.verizon.net/macdouc/osd0002.jpg
Please check it out!
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MARS IS COMING, PART 6
Just as a reminder, Mars will be closest to Earth on December 18/19 and will finally reach opposition with Earth on December 24. As we anticipate these dates please enjoy the next installment on the Red Planet Mars.
Surface Features, Part 1
We know about the character of the Martian terrain from spacecraft photography and altimetry. The Viking orbiters imaged the entire planet at a resolution of roughly 250 meters (820 feet) and selected areas at resolutions down to 10 meters (33 feet). Later the Mars Global Surveyor spacecraft imaged selected areas with resolutions of 1.4 meters (4.6 feet), but it covered only a small fraction of the planet. However, the topography of the Martian surface was determined very accurately with the laser altimeter aboard Mars Global Surveyor, which mapped elevations with a vertical resolution of a few meters.
Despite its small size, Mars has a greater range of elevation than Earth. The lowest point on the planet, within the Hellas impact basin, is 8 km (5 miles) below the reference level. The highest point, at the summit of the volcano Olympus Mons, is 21 km (13 miles) above the reference level. So the elevation range is 29 km (18 miles), compared with about 20 km (12.4 miles) on Earth (or, from the bottom of the Mariana Trench to the top of Mount Everest). Because Mars has no oceans, a reference level for elevations had to be defined in terms other than sea level. At first, in the early 1970s, the elevation at which the atmospheric pressure is 6.l millibars (about 0.006 of the sea-level pressure on Earth) was set as the reference. Later, when Mars Global Surveyor acquired more accurate elevation data, a better reference was needed, and the planet's mean radius of 3,389.51 km (2,106.14 miles) was chosen.
As we noted in our first installment, one of the most striking aspects of the Martian surface is the contrast between the southern and northern hemispheres. Most of the southern hemisphere is upland and heavily cratered, resembling the battered highlands of the Moon. Most of the northern hemisphere is lowland and volcanic with few craters. The difference in mean elevation between the two hemispheres is roughly 6 km (3.7 miles). The topographic boundary between the hemispheres is not at the equator but in a very jagged line around 30° north latitude. In some places the boundary is broad and irregular; in other places there are steep cliffs. Some of the most intensely eroded areas on Mars occur along the boundary. Landforms there include outflow channels, areas of collapse called chaotic terrain, and an enigmatic mix of valleys and ridges known as fretted terrain. Straddling the two hemispheres on one side of the planet is the Tharsis rise, a vast volcanic dome standing 8 km (5 miles) above Mars's mean radius, 12 km (7.5 miles) above the northern plains, and more than 2 km (1.2 miles) above the surrounding cratered southern highlands. On or near the Tharsis rise are the planet's largest volcanoes (see the section Tharsis and Elysium, below). Conspicuously absent in either hemisphere are the types of landforms that on Earth result from plate tectonics—for example, long linear mountain chains similar to the Andes, oceanic trenches, or a global system of interconnected ridges.
The reason for the differences between the hemispheres is one of many unexplained Martian mysteries—it may have formed when one or more large asteroids collided with Mars early in its history or as a result of internal changes that occurred when the planetary core formed. Gravity data acquired by Mars Global Surveyor suggests that the Martian crust is much thicker under the southern highlands than under the northern plains.
The number of very large craters in the southern highlands implies the surface is very, very old. Planetary scientists have established from lunar samples returned by Apollo missions that the rate of large asteroid impacts on the Moon declined rapidly between 3.8 billion and 3.5 billion years ago. Surfaces that formed before this time are heavily cratered; those that formed after are less so. Mars very likely had a similar cratering history. Thus, the southern highlands probably formed more than 3.5 billion years ago.
The southern terrain has many different types of craters—huge impact basins; large, partially filled craters with shallow, flat floors and eroded rims; smaller, fresh-looking bowl-shaped craters like those on the Moon; and rampart and pedestal craters. Hellas is the largest impact basin on Mars. According to Mars Global Surveyor altimetry data, the feature is about 7,000 km (4,400 miles) across, including the broad elevated ring that surrounds the depression, and 8 km (5 miles) deep—much larger than was previously thought. Most of the craters measuring tens to hundreds of kilometers across are highly eroded. Because larger craters tend to be older than smaller ones, erosion rates on early Mars appear to have been much higher than on later Mars. It is one reason why we think the climate on early Mars was very different from what it was for most of the planet's later history.
Rampart craters and pedestal craters may be unique to Mars. A rampart crater gets its name from the lobes of ejecta—the material thrown out from the crater and extending around it—are bordered with a low ridge, or rampart. So the ejecta apparently flowed across the ground, which may indicate that it had a mudlike consistency. Some scientists have suggested that the mud formed from a mixture of impact debris and water that was present under the surface. Around a pedestal crater, the ejected material forms a steep-sided platform, or pedestal, with the crater situated inside its border. The pedestal appears to have developed when wind carved away the surface layer of the surrounding region while leaving intact that portion protected by the overlying ejecta.
The high-resolution Viking images showed us an additional characteristic of the ancient southern terrain—the many networks of small valleys that look like the terrestrial drainage systems that are created by flowing water. Examples include Nirgal Vallis, located in the southern hemisphere north of the Argyre impact basin, and Nanedi Vallis, located just north of the equator near the east end of Valles Marineris. Scientists have suggested two alternative methods for their formation, either the runoff of rainfall on the surface or erosion by the outflow of groundwater that seeped onto the surface. In either case, warm climatic conditions may have been required for their formation. A major surprise of the Mars Global Surveyor mission was the observation of small, fresh-appearing gullies on steep slopes at high latitudes. These features look very much like water-worn gullies in Earth's desert regions, but their origin is still hotly debated. Although the discoverers initially proposed they were caused by water erosion, this was challenged by other researchers.
Next time: “Surface Features, Part 2”
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Dec 12 – the Moon occults Asteroid 4 Vesta
Dec 13 – Peak of the Geminid meteor shower
Dec 14 – the Moon occults the planet Neptune
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THIS WEEK IN HISTORY
Dec 10, 1950 – St. Louis meteorite fall, which hit a car
Dec 10, 1974 – Launch of the Helios 1 solar orbiter mission
Dec 10, 1984 – Claxton meteorite fall, hit a mailbox
Dec 10, 1992 – Mihonoseki meteorite fall, 15th anniversary, which fell through the roof of a house in Japan
Dec 10, 1999 – Launch of the X-ray Multi-Mirror Mission (XMM-Newton)
Dec 12, 1961 – Launch of Oscar 1
Dec 12, 1967 – Pioneer 8 launch, 40th anniversary
Dec 12, 2004 – Landing of Mars Exploration Rover “Opportunity”
Dec 13, 1867 – 140th birthday of Kristian Olaf Bernhard Birkeland
Dec 13, 1904 – Birthday of Sir William Hunter McCrea
Dec 13, 1972 – Apollo 17 lifted off from the moon; 35 years since a human walked on the moon
Dec 14, 1546 – Tycho Brahe’s birthday
Dec 14, 1962 – Mariner 2, Venus flyby, 45th anniversary
Dec 15, 1965 – Launch of NASA’s Gemini 6, Earth-orbital mission with astronauts Walter Schirra and Thomas Stafford
Dec 15, 1966 - Audouin Dollfus' discovery of Saturn’s moon Janus
Dec 15, 1970 – Landing of Soviet probe Venera 7 on Venus
Dec 15, 1984 – Launch of Vega 1, the Soviet Venus/Comet Halley mission
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MUSICAL DIVERSION
Bunessan is a small village on the Ross of Mull in the south of the island of Mull on the west coast of Scotland. The village name in Scottish Gaelic is Bun Easain, meaning “Foot of the little waterfall,” referring to a nearby waterfall. The village was originally a small community of farmers that practiced the Scottish farming tradition called crofting. In crofting, the landowner or their tenant, called the crofter, worked their holding, the croft, to make a living from the fruit of the land and the fruit of their labors. In many crofting communities the adjacent crofters practiced different endeavors that complemented and benefited each other. Until the 1900s, Bunessan had a mill, weavers and a small fishing fleet.
Not far from Bunessan, in the crofting community of Ardtun, lived Mary Macdonald (1789 – 1872), the daughter of a Baptist cleric who wrote songs and poetry in her native language of Gaelic. One of her songs told the story of the birth of the baby Jesus, who was foretold by prophets, announced by angels, lord of all, yet sleeping in a humble feed trough. Macdonald set her words to the tune of a traditional Gaelic melody. She called the song “Leanabh an Àigh” (Child in the Manger).
Leanabh an Àigh
Leanabh an àigh, an Leanabh aig Màiri
Rugadh san stàball, Rìgh nan Dùl;
Thàinig do’n fhàsach, dh’fhuiling ’n ar n-àite
Son’ iad an àireamh bhitheas dhà dlùth!
Ged a bhios leanabain aig rìghrean na talmhainn
An greadhnachas garbh is anabarr mùirn,
’S geàrr gus am falbh iad, ’s fasaidh iad anfhann,
An àilleachd ’s an dealbh a’ searg san ùir.
Cha b’ionann ’s an t-Uan thàinig gur fuasgladh
Iriosal, stuama ghluais e’n tùs;
E naomh gun truailleachd, Cruithfhear an t-sluaigh,
Dh’éirich e suas le buaidh o ùir.
Leanabh an àigh, mar dh’aithris na fàidhean;
’S na h-àinglean àrd’, b’e miann an sùl;
’S E ’s airidh air gràdh ’s air urram thoirt dhà
Sona an àireamh bhitheas dhà dlùth.
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A few decades later, the song was revived by a fellow Scott, Lachlan Macbean (1853 – 1931). Macbean edited The Fifeshire Advertiser, a newspaper in Kirkcaldy. In addition to his day job, Macbean had a passion for resurrecting nearly forgotten Gaelic songs. One of his published collections, entitled “Songs and Hymns of the Gael” (Edinburgh, Scotland: 1888) included an English translation of Macdonald’s song of the child in the manger. In her memory, Macbean named the song’s melody “Bunessan,” after the nearby village.
Child in the Manger
Child in the manger, Infant of Mary,
Outcast and Stranger, Lord of all,
Child Who inherits all our transgressions,
All our demerits on Him fall.
Once the most holy Child of salvation
Gently and lowly lived below.
Now as our glorious mighty Redeemer,
See Him victorious o’er each foe.
Prophets foretold Him, Infant of wonder;
Angels behold Him on His throne.
Worthy our Savior of all our praises;
Happy forever are His own.
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In 1922, English author Eleanor Farjeon (1881 – 1965) wrote a poem entitled “A Morning Song (For the First Day of Spring). The words were set to the “Bunessan” melody, creating the hymn we know today as “Morning Has Broken.” Though not all of the words are typically sung today, the full text follows.
Morning Has Broken
Morning has broken, like the first morning
Blackbird has spoken, like the first bird
Praise for the singing, praise for the morning
Praise for the springing fresh from the word
Sweet the rain's new fall, sunlit from heaven
Like the first dewfall, on the first grass
Praise for the sweetness of the wet garden
Sprung in completeness where his feet pass
Mine is the sunlight, mine is the morning
Born of the one light, Eden saw play
Praise with elation, praise every morning
God's recreation of the new day
(Below is the second have of Farjeon’s text.)
Cool the gray clouds roll, peaking the mountains,
Gull in her free flight, swooping the skies:
Praise for the mystery misting the morning
Behind the shadow, waiting to shine.
I am the sunrise, warming the heavens,
Spilling my warm glow, over the earth:
Praise for the brightness of this new morning
Filling my spirit with Your great love.
Mine is a turning, mine is a new life;
Mine is a journey closer to You:
Praise for the sweet glimpse caught in a moment,
Joy breathing deeply, dancing in flight.
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In 1969, a Jesuit priest, Rev. James Quinn, published a collection of new songs entitled, “New Hymns for All Seasons” (London). One of his songs was set to the “Bunessan” melody. The text, called “St. Patrick’s Breastplate,” is a morning prayer for strength and guidance through the coming day. The song is also called by its first line, “This Day God Gives Me.”
This Day God Gives Me
(St. Patrick's Breastplate)
This day God gives me Strength of high heaven
Sun and Moon shining, Flame in my hearth
Flashing of lightning, Wind in its swiftness,
Deeps of the ocean, Firmness of earth.
This day God sends me Strength as my guardian,
Might to uphold me, Wisdom as guide.
Your eyes are watchful, your ears are list’ning,
Your lips are speaking, Friend at my side.
God’s way is my way, God’s shield is ‘round me,
God’s host defends me, Saving from ill.
Angels of heaven, Drive from me always
All that would harm me, Stand by me still.
Rising I thank you, Mighty and Strong One
King of creation, Giver of rest.
Firmly confessing Threeness of Persons
Oneness of Godhead, Trinity blest.
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Today, the Scottish village of Bunessan has a population of roughly 200, and includes surrounding areas of Millbrae, Fountainhead and Ardtun. There is a monument to Mary Macdonald near the village, on the road toward Craignure, just after the Knockan crossroads. The ruins of her house can still be found nearby.
To see and hear more on the hymn, “Leanabh an Àigh,” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/non/gd/leanabh.htm
To see and hear more on the hymn, “Child in the Manger,” visit this page of “The Cyber Hymnal” - http://www.cyberhymnal.org/htm/c/h/childman.htm
To see and hear more on the hymn, “Morning Has Broken,” visit this page of “The Cyber Hymnal” - http://www.allspirit.co.uk/morning.html
To view the text of the hymn, “This Day God Gives Me,” visit this Web page:
http://www.janson.com/info/prayer.html
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Sunday, December 09, 2007
Sunday, December 02, 2007
White Dwarf Stars Found With Carbon Atmospheres
Recently, nine white dwarf stars were found with atmospheres primarily composed of carbon, with little or no trace of hydrogen or helium. The stars are considered rare. They could become a new category of star. Because they are not like the known classes of white dwarf stars, their evolution is still uncertain. An article on the study was published in the November 22 issue of the journal Nature. The report is written by Professors Patrick Dufour and James Liebert of the Department of Astronomy and Steward Observatory, University of Arizona, and their colleagues at the Université de Montréal and Paris Observatory. The discovery could offer new insight on the hearts of dying stars.
White dwarfs are the stars of relatively small mass that are in the last stage of their evolution. They start out as normal stars, but over billions of years, they expand into red giants before exhausting their energy and collapsing into objects not much bigger than Earth. Stars of larger mass usually end as either black holes or neutron stars (sometimes called pulsars).
When a star burns helium, it leaves "ashes" or "residue" of carbon and oxygen. When its nuclear fuel is exhausted, the star then dies as a white dwarf, which is an extremely dense object that packs the mass of our sun into an object about the size of Earth. The theory of stellar evolution predicts that most white dwarfs have a core made of carbon and oxygen, which is surrounded by a layer of helium and, for 80% of them, an additional layer of hydrogen. Astronomers didn't expect stars to find dwarf stars with carbon atmospheres. Some even suggest they might be seeing the bare stellar core.
The recently identified dwarf stars may have evolved in a way astronomers didn't know before. For example, they may have begun as stars that were more massive, but not quite massive enough to explode as supernovae. It seems that all but the most massive two or three percent of stars eventually die as white dwarfs rather than explode as supernovae.
The nine stars were discovered among 10,000 new white dwarf stars found in the Sloan Digital Sky Survey (SDSS). The survey found about four times the number of white dwarf stars previously known.
Liebert identified a few dozens of the newfound white dwarfs as "DQ" white dwarfs in 2003. When observed in optical light, DQ stars appear to be mostly helium and carbon. Astronomers think that convection in the helium zone pulls up carbon from the star's carbon-oxygen core.
Dufour developed a model to analyze the atmospheres of DQ stars as part of his doctoral research at the Université de Montréal. His model simulated cool DQ stars, stars at temperatures between 5,000 and 12,000 Kelvin. For reference, our sun's surface temperature is around 5,780 Kelvin.
When Dufour joined Steward Observatory in January of 2007, he updated his code to analyze hotter stars, stars as hot as 24,000 Kelvin.
When Dufour began modeling the atmospheres of the hotter DQ stars, he at first thought they were helium-rich stars with traces of carbon, just like the cooler ones, but the model did not agree with the SDSS data. Dufour gradually adjusted his model to have a larger and larger abundance of carbon, but the model still didn't agree. Then in May of 2007, in desperation, Dufour calculated a model with a pure-carbon atmosphere and it worked, exactly reproducing the observed spectra of the hotter DQ stars. Until this time, no one had ever calculated a pure carbon atmosphere model, because no one thought it existed. Astronomers are very excited by the news.
As of this writing, Dufour and his colleagues have identified eight carbon-dominated atmosphere white dwarf stars among about 200 DQ stars they've checked in the SDSS data.
For the team, the biggest question is why the carbon-atmosphere stars are found only between about 18,000 and 23,000 Kelvin. The stars are too hot to be explained by the standard convective dredge-up scenario, so there must be another explanation.
Dufour and Liebert think these stars might have evolved from a star like the unique, much hotter star called H1504+65 that was reported in 1986 by Pennsylvania State University astronomer John A. Nousek, Liebert and others. If this is so, carbon-atmosphere stars represent a previously unknown sequence of stellar evolution.
H1504+65 is a very massive and very hot star with a surface temperature of 200,000 Kelvin. Astronomers currently think the star somehow violently expelled all its hydrogen and all but a very small trace of its helium, leaving an essentially bare stellar nucleus with a surface of 50 percent carbon and 50 percent oxygen.
Dufour and Liebert think that when a star like H1504+65 cools, it eventually becomes like the pure-carbon stars. As the massive star cools, gravity separates the carbon, oxygen and trace helium. Above 25,000 Kelvin, the trace helium rises to the top, forming a thin layer above the much more massive carbon envelope, effectively disguising the star as a helium-atmosphere white dwarf, Dufour and Liebert said.
But between 18,000 and 23,000 Kelvin, convection in the carbon zone probably dilutes the thin helium layer. At these temperatures, oxygen, which is heavier than carbon, has probably sunk too deep to be pulled to the surface by convection.
Dufour and his colleagues say that models of stars of 9 to 11 solar masses might explain their peculiar carbon stars. In 1999, astronomers predicted that stars of this mass would become white dwarfs with oxygen-magnesium-neon cores and mostly carbon-oxygen atmospheres. Anything larger was thought to explode as a supernova. Now, scientists aren't sure where the dividing line is, whether stars of eight, nine, 10 or 11 solar masses are required to create supernovae.
The UA astronomers plan making new observations of the carbon atmosphere stars at the 6.5-meter MMT Observatory on Mount Hopkins, Ariz., in December to better pinpoint their masses. The observations could help define the mass limit for stars dying as white dwarfs or dying as supernovae.
To learn more about the University of Arizona Department of Astronomy and Steward Observatory, visit their home page: http://www.as.arizona.edu/
To learn more about the Sloan Digital Sky Survey (SDSS), visit their home page: http://www.sdss.org/
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MARS IS COMING, PART 5
As the December 24 opposition approaches, please enjoy this fifth installment on the Red Planet Mars.
The Polar Caps
Early each southern spring, the southern carbon dioxide cap begins to recede from its maximum extent of 50° S. As spring progresses, the cap shrinks by as much as 1° of latitude every five Earth days. The edge of the cap becomes ragged, controlled by the local topography (e.g., craters), and eventually it breaks into well-defined fragments. From year to year, the location of the fragments remains about the same, although there are small variations in detail. Over the course of one-third of the Martian year, the cap recedes to its smallest extent; it is then not usually visible from Earth, but spacecraft observations have confirmed the presence of a small remnant throughout the summer.
Re-growth of the southern cap begins, after a brief period of atmospheric clarity, with the rapid formation of obscuring clouds called the polar hood. On occasion the hood is transparent enough to red light so that spacecraft may view the formation of the cap. These limited opportunities, however, have not allowed the cap’s rate of advance toward the equator to be accurately known. The polar hood (the cloud cover) is far more extensive than the cap itself and can reach to within 35° of the equator. The hood is thought to contain particles of frozen water and carbon dioxide.
Differences in the behavior of the northern carbon dioxide cap—including its smaller maximum size in winter and complete disappearance in summer—are due to (1) differences in the lengths of seasons for the two hemispheres, (2) in the distances from the sun during their respective winters, and (3) in elevation between the two poles. The recession of the seasonal cap in the north is much more regular than in the south because of the level plains that are spread over much of the high northern latitudes. The advance of the northern polar cap has been less well observed than in the south because of thicker and more extensive polar clouds.
The composition of the seasonal polar caps was the subject of debate for nearly 200 years. Herschel was responsible for one early hypothesis that the caps were made of water ice. Herschel had imagined them to be just like those on Earth. In 1898 an Irish scientist, George J. Stoney, questioned Herschel’s theory and suggested that the caps might be made of frozen carbon dioxide, but evidence to support the idea was not available until Kuiper's 1947 discovery of carbon dioxide in the atmosphere.
In 1966 the American scientists Robert Leighton and Bruce Murray published the results of a numerical model of the thermal environment on Mars that raised considerable doubt about the water ice hypothesis. Their calculations indicated that, under Martian conditions, atmospheric carbon dioxide would freeze at the poles, and the growth and shrinkage of their model carbon dioxide caps mimicked the observed behavior of the actual caps. The model predicted that the seasonal caps were relatively thin, only a few meters deep near the poles and thinning toward the equator. Although the model was based on simplifications of the actual conditions on Mars, their results were later confirmed by thermal and spectral measurements taken by the twin Mariner 6 and 7 spacecraft when they flew by Mars in 1969.
The composition of the summer remnant caps, particularly the southern one, remains somewhat less certain despite considerable data on their ability to collect and radiate thermal energy. Measurements by the Viking orbiters showed that the ice of the northern cap remnant is definitely frozen water. Added to this evidence is the large increase in the amount of water vapor detected in the atmosphere over the summer cap. The northern remnant cap, in fact, represents the largest known reservoir of available water on the planet. At the southern pole, the carbon dioxide cap does not completely disappear in summer. A small remnant, consisting mostly of carbon dioxide but containing as much as 10 percent water, remains. Measurements by the Mars Express orbiter in 2004 revealed that water ice also is present just below the surface over wide areas around the remnant cap. Almost no water vapor is normally observed in the atmosphere above the southern remnant cap.
The topography of the polar regions is among the most distinctive on Mars. Beneath the seasonal and remnant caps at both poles are stacks of layered deposits up to 3 km (2 miles) thick that extend out to about the 80° latitude circle. The layers are exposed in escarpments and valleys that have a distinctive spiral pattern. Water ice has been detected in the upper 1 meter (about 3.3 feet) of the layered terrains at both poles, and the entire stack of layered deposits at each location is likely to be mostly water ice with variable amounts of dust. The layering is thought to result from climate-caused variations in the deposition rates of dust and water ice, which are traceable to changes in the planet's orbit and rotation. The layered terrains in the north lack impact craters, suggesting that they are very young. In contrast, the cratering of the layered terrains in the south indicate an age of roughly 100 million years.
The northern polar region also contains the largest area of sand dunes on Mars. The dunes, which occupy the northern part of the plain known as Vastitas Borealis, form a band that almost completely encircles the north polar remnant cap. Interlayering of sand and seasonal carbon dioxide snow can be seen in some locations, indicating that the dunes are active on at least a seasonal timescale.
Next time: “Surface Features, Part 1”
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Dec 1, 7:44 A.M. ET - Last Quarter Moon
Dec 1 - Saturn 2° north of Moon
Dec 5 - Venus is 7° north of the Moon
Dec 6 - Moon at apogee, the point in the Moon's orbit when it is farthest from Earth.
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THIS WEEK IN HISTORY
Dec 7, 1972 – Apollo 17 launch, last manned mission to the Moon, 35th anniversary
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MUSICAL DIVERSION
In the late sixteenth century in the western Finland town of Turku, the rector (principal) of the Cathedral School of the local Catholic diocese took on the task of collecting, preserving and perpetuating the late medieval (thirteenth century) Latin songs that were still sung during his century in the Finnish cathedral schools. The name of the man was Jaakko Finne (or Jaakko Suomalainen), who was also a hymnist and who wrote under the Latinized penname Jacobus Finno (ca. 1540-1588). The collected songs were finally published in 1582 with the funding of a Finnish student named Theodoric Petri of Nyland, a member of an aristocratic family who was known by other names, but is remembered in print as Theodoricus Petri Nylandensi (ca. 1560- ca. 1630).
The song collection became known simply at "Piae Cantiones," but its full title was "Piae Cantiones ecclesiasticae et scholasticae veterum episcoporum" (Devout ecclesiastical and school songs of the old bishops). The collection included 74 songs that give insight to medieval Catholic culture. The origin of the songs and melodies varies and most of the songs are religious in nature, but some are secular school songs. One such school song, by author unknown, was called "Tempus Adest Floridum," Latin, meaning "Now Come the Flowers." The song celebrates the coming of spring, the warming of the earth and the blooming of the flowers.
Tempus Adest Floridum
Tempus adest floridum, surgent namque flores
Vernales in omnibus, imitantur mores
Hoc quod frigus laeserat, reparant calores
Cernimus hoc fieri, per multos labores.
Sunt prata plena floribus, iucunda aspectu
Ubi iuvat cernere, herbas cum delectu
Gramina et plantae hyeme quiescunt
Vernali in tempore virent et accrescunt.
Haec vobis pulchre monstrant Deum creatorem
Quem quoque nos credimus omnium factorem
O tempus ergo hilare, quo laetari libet
Renovato nam mundo, nos novari decet.
Terra ornatur floribus et multo decore
Nos honestis moribus et vero amore
Gaudeamus igitur tempore iucundo
Laudemusque Dominum pectoris ex fundo.
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In 1853 a new collection of Christmas songs was published by hymnist John Mason Neale (1818-1866) and minister and chorister Thomas Helmore (1811 – 1890). The collection was entitled "Carols for ChristmasTide" and included a carol by Neale that he may actually have written a few years earlier. The text was a tale of a young man named Václav (pronounced "VAHT-slaf"), who was the son of Duke Vratislav I of Bohemia. Václav was born around 907 in Prague, Bohemia (now part of the Czech Republic). Christianity spread through Bohemia during his reign as duke, which began about 924 or 925 when he assumed the throne at the age of eighteen. On September 28, 935, Václav was murdered on his way to church in a plot organized by his younger brother, Boleslav, who succeeded him as duke. Numerous saintly stories about Václav circulated following his death, as well as a few miracles that were attributed to his name. Václav was later venerated as a saint in both the Roman Catholic Church and the Orthodox Church, and there is a major shrine to him at St Vitus Cathedral in Prague.
The carol takes place in the Bohemian bitter cold of December 26, the feast day of Saint Stephen, whose stoning is recounted in the Acts of the Apostles (the Book of Acts). Neale set his new carol text to the tune of the old medieval Latin school song "Tempus Adest Floridum." And rather than use his Czech name of Václav, Neale called him the name by which he was better known in the west-- Wenceslas.
Good King Wenceslas
Good King Wenceslas looked out on the Feast of Stephen,
When the snow lay round about, deep and crisp and even.
Brightly shone the moon that night, though the frost was cruel,
When a poor man came in sight, gathering winter fuel.
“Hither, page, and stand by me, if you know it, telling,
Yonder peasant, who is he? Where and what his dwelling?”
“Sire, he lives a good league hence, underneath the mountain,
Right against the forest fence, by Saint Agnes’ fountain.”
“Bring me food and bring me wine, bring me pine logs hither,
You and I will see him dine, when we bear them thither.”
Page and monarch, forth they went, forth they went together,
Through the cold wind’s wild lament and the bitter weather.
“Sire, the night is darker now, and the wind blows stronger,
Fails my heart, I know not how; I can go no longer.”
“Mark my footsteps, my good page, tread now in them boldly,
You shall find the winter’s rage freeze your blood less coldly.”
In his master’s steps he trod, where the snow lay dinted;
Heat was in the very sod which the saint had printed.
Therefore, Christian men, be sure, wealth or rank possessing,
You who now will bless the poor shall yourselves find blessing.
-----
In 1919, another Christmas song was published by British-Canadian minister Joseph Simpson Cook (1859 – 1933). Cook recounted the story of the birth of Jesus and set his text to the tune of our favorite thirteenth century school song.
Gentle Mary Laid Her Child
Gentle Mary laid her Child lowly in a manger;
There He lay, the undefiled, to the world a Stranger:
Such a Babe in such a place, can He be the Savior?
Ask the saved of all the race who have found His favor.
Angels sang about His birth; wise men sought and found Him;
Heaven’s star shone brightly forth, glory all around Him:
Shepherds saw the wondrous sight, heard the angels singing;
All the plains were lit that night, all the hills were ringing.
Gentle Mary laid her Child lowly in a manger;
He is still the undefiled, but no more a stranger:
Son of God, of humble birth, beautiful the story;
Praise His Name in all the earth, hail the King of glory!
-----
To see and hear more on the hymn, "Temus Adest Floridum" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/non/la/tempusade.htm
To see and hear more on the hymn, "Gentle Mary Laid Her Child
" visit this page of "The Cyber Hymnal" -http://www.cyberhymnal.org/htm/g/e/gentleml.htm
To see and hear more on the hymn, "Gentle Mary Laid Her Child" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/g/e/gentleml.htm
Recently, nine white dwarf stars were found with atmospheres primarily composed of carbon, with little or no trace of hydrogen or helium. The stars are considered rare. They could become a new category of star. Because they are not like the known classes of white dwarf stars, their evolution is still uncertain. An article on the study was published in the November 22 issue of the journal Nature. The report is written by Professors Patrick Dufour and James Liebert of the Department of Astronomy and Steward Observatory, University of Arizona, and their colleagues at the Université de Montréal and Paris Observatory. The discovery could offer new insight on the hearts of dying stars.
White dwarfs are the stars of relatively small mass that are in the last stage of their evolution. They start out as normal stars, but over billions of years, they expand into red giants before exhausting their energy and collapsing into objects not much bigger than Earth. Stars of larger mass usually end as either black holes or neutron stars (sometimes called pulsars).
When a star burns helium, it leaves "ashes" or "residue" of carbon and oxygen. When its nuclear fuel is exhausted, the star then dies as a white dwarf, which is an extremely dense object that packs the mass of our sun into an object about the size of Earth. The theory of stellar evolution predicts that most white dwarfs have a core made of carbon and oxygen, which is surrounded by a layer of helium and, for 80% of them, an additional layer of hydrogen. Astronomers didn't expect stars to find dwarf stars with carbon atmospheres. Some even suggest they might be seeing the bare stellar core.
The recently identified dwarf stars may have evolved in a way astronomers didn't know before. For example, they may have begun as stars that were more massive, but not quite massive enough to explode as supernovae. It seems that all but the most massive two or three percent of stars eventually die as white dwarfs rather than explode as supernovae.
The nine stars were discovered among 10,000 new white dwarf stars found in the Sloan Digital Sky Survey (SDSS). The survey found about four times the number of white dwarf stars previously known.
Liebert identified a few dozens of the newfound white dwarfs as "DQ" white dwarfs in 2003. When observed in optical light, DQ stars appear to be mostly helium and carbon. Astronomers think that convection in the helium zone pulls up carbon from the star's carbon-oxygen core.
Dufour developed a model to analyze the atmospheres of DQ stars as part of his doctoral research at the Université de Montréal. His model simulated cool DQ stars, stars at temperatures between 5,000 and 12,000 Kelvin. For reference, our sun's surface temperature is around 5,780 Kelvin.
When Dufour joined Steward Observatory in January of 2007, he updated his code to analyze hotter stars, stars as hot as 24,000 Kelvin.
When Dufour began modeling the atmospheres of the hotter DQ stars, he at first thought they were helium-rich stars with traces of carbon, just like the cooler ones, but the model did not agree with the SDSS data. Dufour gradually adjusted his model to have a larger and larger abundance of carbon, but the model still didn't agree. Then in May of 2007, in desperation, Dufour calculated a model with a pure-carbon atmosphere and it worked, exactly reproducing the observed spectra of the hotter DQ stars. Until this time, no one had ever calculated a pure carbon atmosphere model, because no one thought it existed. Astronomers are very excited by the news.
As of this writing, Dufour and his colleagues have identified eight carbon-dominated atmosphere white dwarf stars among about 200 DQ stars they've checked in the SDSS data.
For the team, the biggest question is why the carbon-atmosphere stars are found only between about 18,000 and 23,000 Kelvin. The stars are too hot to be explained by the standard convective dredge-up scenario, so there must be another explanation.
Dufour and Liebert think these stars might have evolved from a star like the unique, much hotter star called H1504+65 that was reported in 1986 by Pennsylvania State University astronomer John A. Nousek, Liebert and others. If this is so, carbon-atmosphere stars represent a previously unknown sequence of stellar evolution.
H1504+65 is a very massive and very hot star with a surface temperature of 200,000 Kelvin. Astronomers currently think the star somehow violently expelled all its hydrogen and all but a very small trace of its helium, leaving an essentially bare stellar nucleus with a surface of 50 percent carbon and 50 percent oxygen.
Dufour and Liebert think that when a star like H1504+65 cools, it eventually becomes like the pure-carbon stars. As the massive star cools, gravity separates the carbon, oxygen and trace helium. Above 25,000 Kelvin, the trace helium rises to the top, forming a thin layer above the much more massive carbon envelope, effectively disguising the star as a helium-atmosphere white dwarf, Dufour and Liebert said.
But between 18,000 and 23,000 Kelvin, convection in the carbon zone probably dilutes the thin helium layer. At these temperatures, oxygen, which is heavier than carbon, has probably sunk too deep to be pulled to the surface by convection.
Dufour and his colleagues say that models of stars of 9 to 11 solar masses might explain their peculiar carbon stars. In 1999, astronomers predicted that stars of this mass would become white dwarfs with oxygen-magnesium-neon cores and mostly carbon-oxygen atmospheres. Anything larger was thought to explode as a supernova. Now, scientists aren't sure where the dividing line is, whether stars of eight, nine, 10 or 11 solar masses are required to create supernovae.
The UA astronomers plan making new observations of the carbon atmosphere stars at the 6.5-meter MMT Observatory on Mount Hopkins, Ariz., in December to better pinpoint their masses. The observations could help define the mass limit for stars dying as white dwarfs or dying as supernovae.
To learn more about the University of Arizona Department of Astronomy and Steward Observatory, visit their home page: http://www.as.arizona.edu/
To learn more about the Sloan Digital Sky Survey (SDSS), visit their home page: http://www.sdss.org/
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MARS IS COMING, PART 5
As the December 24 opposition approaches, please enjoy this fifth installment on the Red Planet Mars.
The Polar Caps
Early each southern spring, the southern carbon dioxide cap begins to recede from its maximum extent of 50° S. As spring progresses, the cap shrinks by as much as 1° of latitude every five Earth days. The edge of the cap becomes ragged, controlled by the local topography (e.g., craters), and eventually it breaks into well-defined fragments. From year to year, the location of the fragments remains about the same, although there are small variations in detail. Over the course of one-third of the Martian year, the cap recedes to its smallest extent; it is then not usually visible from Earth, but spacecraft observations have confirmed the presence of a small remnant throughout the summer.
Re-growth of the southern cap begins, after a brief period of atmospheric clarity, with the rapid formation of obscuring clouds called the polar hood. On occasion the hood is transparent enough to red light so that spacecraft may view the formation of the cap. These limited opportunities, however, have not allowed the cap’s rate of advance toward the equator to be accurately known. The polar hood (the cloud cover) is far more extensive than the cap itself and can reach to within 35° of the equator. The hood is thought to contain particles of frozen water and carbon dioxide.
Differences in the behavior of the northern carbon dioxide cap—including its smaller maximum size in winter and complete disappearance in summer—are due to (1) differences in the lengths of seasons for the two hemispheres, (2) in the distances from the sun during their respective winters, and (3) in elevation between the two poles. The recession of the seasonal cap in the north is much more regular than in the south because of the level plains that are spread over much of the high northern latitudes. The advance of the northern polar cap has been less well observed than in the south because of thicker and more extensive polar clouds.
The composition of the seasonal polar caps was the subject of debate for nearly 200 years. Herschel was responsible for one early hypothesis that the caps were made of water ice. Herschel had imagined them to be just like those on Earth. In 1898 an Irish scientist, George J. Stoney, questioned Herschel’s theory and suggested that the caps might be made of frozen carbon dioxide, but evidence to support the idea was not available until Kuiper's 1947 discovery of carbon dioxide in the atmosphere.
In 1966 the American scientists Robert Leighton and Bruce Murray published the results of a numerical model of the thermal environment on Mars that raised considerable doubt about the water ice hypothesis. Their calculations indicated that, under Martian conditions, atmospheric carbon dioxide would freeze at the poles, and the growth and shrinkage of their model carbon dioxide caps mimicked the observed behavior of the actual caps. The model predicted that the seasonal caps were relatively thin, only a few meters deep near the poles and thinning toward the equator. Although the model was based on simplifications of the actual conditions on Mars, their results were later confirmed by thermal and spectral measurements taken by the twin Mariner 6 and 7 spacecraft when they flew by Mars in 1969.
The composition of the summer remnant caps, particularly the southern one, remains somewhat less certain despite considerable data on their ability to collect and radiate thermal energy. Measurements by the Viking orbiters showed that the ice of the northern cap remnant is definitely frozen water. Added to this evidence is the large increase in the amount of water vapor detected in the atmosphere over the summer cap. The northern remnant cap, in fact, represents the largest known reservoir of available water on the planet. At the southern pole, the carbon dioxide cap does not completely disappear in summer. A small remnant, consisting mostly of carbon dioxide but containing as much as 10 percent water, remains. Measurements by the Mars Express orbiter in 2004 revealed that water ice also is present just below the surface over wide areas around the remnant cap. Almost no water vapor is normally observed in the atmosphere above the southern remnant cap.
The topography of the polar regions is among the most distinctive on Mars. Beneath the seasonal and remnant caps at both poles are stacks of layered deposits up to 3 km (2 miles) thick that extend out to about the 80° latitude circle. The layers are exposed in escarpments and valleys that have a distinctive spiral pattern. Water ice has been detected in the upper 1 meter (about 3.3 feet) of the layered terrains at both poles, and the entire stack of layered deposits at each location is likely to be mostly water ice with variable amounts of dust. The layering is thought to result from climate-caused variations in the deposition rates of dust and water ice, which are traceable to changes in the planet's orbit and rotation. The layered terrains in the north lack impact craters, suggesting that they are very young. In contrast, the cratering of the layered terrains in the south indicate an age of roughly 100 million years.
The northern polar region also contains the largest area of sand dunes on Mars. The dunes, which occupy the northern part of the plain known as Vastitas Borealis, form a band that almost completely encircles the north polar remnant cap. Interlayering of sand and seasonal carbon dioxide snow can be seen in some locations, indicating that the dunes are active on at least a seasonal timescale.
Next time: “Surface Features, Part 1”
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Dec 1, 7:44 A.M. ET - Last Quarter Moon
Dec 1 - Saturn 2° north of Moon
Dec 5 - Venus is 7° north of the Moon
Dec 6 - Moon at apogee, the point in the Moon's orbit when it is farthest from Earth.
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THIS WEEK IN HISTORY
Dec 7, 1972 – Apollo 17 launch, last manned mission to the Moon, 35th anniversary
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MUSICAL DIVERSION
In the late sixteenth century in the western Finland town of Turku, the rector (principal) of the Cathedral School of the local Catholic diocese took on the task of collecting, preserving and perpetuating the late medieval (thirteenth century) Latin songs that were still sung during his century in the Finnish cathedral schools. The name of the man was Jaakko Finne (or Jaakko Suomalainen), who was also a hymnist and who wrote under the Latinized penname Jacobus Finno (ca. 1540-1588). The collected songs were finally published in 1582 with the funding of a Finnish student named Theodoric Petri of Nyland, a member of an aristocratic family who was known by other names, but is remembered in print as Theodoricus Petri Nylandensi (ca. 1560- ca. 1630).
The song collection became known simply at "Piae Cantiones," but its full title was "Piae Cantiones ecclesiasticae et scholasticae veterum episcoporum" (Devout ecclesiastical and school songs of the old bishops). The collection included 74 songs that give insight to medieval Catholic culture. The origin of the songs and melodies varies and most of the songs are religious in nature, but some are secular school songs. One such school song, by author unknown, was called "Tempus Adest Floridum," Latin, meaning "Now Come the Flowers." The song celebrates the coming of spring, the warming of the earth and the blooming of the flowers.
Tempus Adest Floridum
Tempus adest floridum, surgent namque flores
Vernales in omnibus, imitantur mores
Hoc quod frigus laeserat, reparant calores
Cernimus hoc fieri, per multos labores.
Sunt prata plena floribus, iucunda aspectu
Ubi iuvat cernere, herbas cum delectu
Gramina et plantae hyeme quiescunt
Vernali in tempore virent et accrescunt.
Haec vobis pulchre monstrant Deum creatorem
Quem quoque nos credimus omnium factorem
O tempus ergo hilare, quo laetari libet
Renovato nam mundo, nos novari decet.
Terra ornatur floribus et multo decore
Nos honestis moribus et vero amore
Gaudeamus igitur tempore iucundo
Laudemusque Dominum pectoris ex fundo.
-----
In 1853 a new collection of Christmas songs was published by hymnist John Mason Neale (1818-1866) and minister and chorister Thomas Helmore (1811 – 1890). The collection was entitled "Carols for ChristmasTide" and included a carol by Neale that he may actually have written a few years earlier. The text was a tale of a young man named Václav (pronounced "VAHT-slaf"), who was the son of Duke Vratislav I of Bohemia. Václav was born around 907 in Prague, Bohemia (now part of the Czech Republic). Christianity spread through Bohemia during his reign as duke, which began about 924 or 925 when he assumed the throne at the age of eighteen. On September 28, 935, Václav was murdered on his way to church in a plot organized by his younger brother, Boleslav, who succeeded him as duke. Numerous saintly stories about Václav circulated following his death, as well as a few miracles that were attributed to his name. Václav was later venerated as a saint in both the Roman Catholic Church and the Orthodox Church, and there is a major shrine to him at St Vitus Cathedral in Prague.
The carol takes place in the Bohemian bitter cold of December 26, the feast day of Saint Stephen, whose stoning is recounted in the Acts of the Apostles (the Book of Acts). Neale set his new carol text to the tune of the old medieval Latin school song "Tempus Adest Floridum." And rather than use his Czech name of Václav, Neale called him the name by which he was better known in the west-- Wenceslas.
Good King Wenceslas
Good King Wenceslas looked out on the Feast of Stephen,
When the snow lay round about, deep and crisp and even.
Brightly shone the moon that night, though the frost was cruel,
When a poor man came in sight, gathering winter fuel.
“Hither, page, and stand by me, if you know it, telling,
Yonder peasant, who is he? Where and what his dwelling?”
“Sire, he lives a good league hence, underneath the mountain,
Right against the forest fence, by Saint Agnes’ fountain.”
“Bring me food and bring me wine, bring me pine logs hither,
You and I will see him dine, when we bear them thither.”
Page and monarch, forth they went, forth they went together,
Through the cold wind’s wild lament and the bitter weather.
“Sire, the night is darker now, and the wind blows stronger,
Fails my heart, I know not how; I can go no longer.”
“Mark my footsteps, my good page, tread now in them boldly,
You shall find the winter’s rage freeze your blood less coldly.”
In his master’s steps he trod, where the snow lay dinted;
Heat was in the very sod which the saint had printed.
Therefore, Christian men, be sure, wealth or rank possessing,
You who now will bless the poor shall yourselves find blessing.
-----
In 1919, another Christmas song was published by British-Canadian minister Joseph Simpson Cook (1859 – 1933). Cook recounted the story of the birth of Jesus and set his text to the tune of our favorite thirteenth century school song.
Gentle Mary Laid Her Child
Gentle Mary laid her Child lowly in a manger;
There He lay, the undefiled, to the world a Stranger:
Such a Babe in such a place, can He be the Savior?
Ask the saved of all the race who have found His favor.
Angels sang about His birth; wise men sought and found Him;
Heaven’s star shone brightly forth, glory all around Him:
Shepherds saw the wondrous sight, heard the angels singing;
All the plains were lit that night, all the hills were ringing.
Gentle Mary laid her Child lowly in a manger;
He is still the undefiled, but no more a stranger:
Son of God, of humble birth, beautiful the story;
Praise His Name in all the earth, hail the King of glory!
-----
To see and hear more on the hymn, "Temus Adest Floridum" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/non/la/tempusade.htm
To see and hear more on the hymn, "Gentle Mary Laid Her Child
" visit this page of "The Cyber Hymnal" -http://www.cyberhymnal.org/htm/g/e/gentleml.htm
To see and hear more on the hymn, "Gentle Mary Laid Her Child" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/g/e/gentleml.htm
Monday, November 26, 2007
Damaged Genesis Yields Data on Solar Wind
The goal of NASA's Genesis mission was to collect samples of the solar wind and return them to Earth for study. The Genesis spacecraft spent 27 months in space, gathering tiny particles from different types of solar wind. It then returned to Earth and ejected its sealed sample capsule for Earth re-entry and a gentle airborne recovery by helicopter. Unfortunately the planned parachute-capture of the capsule was not possible because the parachute failed to deploy. The sad result was the creation of a new small crater in the Utah desert. Observers of the crash were initially devastated, but the mission team soon realized that data could still be salvaged, though more slowly and with more effort.
The results, picked from millimeter-sized shards of the spacecraft's detectors, provide a snapshot of the early solar system, and will feed into models that outline how our planet’s atmosphere evolved.
The team originally hoped they could publish a series of papers within a year of the return. It has taken much longer, but as of late October a series of four papers had been published in Space Science Reviews and a fifth paper appeared the week of October 14 in Science. In addition, a preliminary paper was published last year.
The team remains hopeful that they will soon be able to complete the main goal of their original mission: solving the mystery of the unique isotopic signature of different objects in our galaxy.
The recent paper in Science contains a study of the ratio of different isotopes of neon and argon obtained from samples of three types of solar wind: fast, slow, and coronal mass ejections from the sun’s surface. The researchers conclude that these ratios are essentially the same in all three types of wind. This is good news: it indicates that the elements of main interest to the researchers have the same isotopic signature in the solar wind as in the sun itself.
That’s useful because the outer layer of the sun is thought to provide a picture of isotopic ratios in the very early solar system, before stars or planets were formed. Scientists had previously been concern that there would be a difference between the compositions of the solar wind and the sun itself.
The isotopic ratios of neon and argon are not in themselves very surprising — scientists already had a fairly good measure of these values from previous missions, including one low-tech scheme during the Apollo program in which a screen was laid out on the Moon to collect solar-wind samples. But they improve by a factor of 60 the precision with which the argon isotope ratio is known. This will be useful for researchers who model the early solar system to work out processes such as how Earth’s atmosphere formed.
As expected, the Genesis samples have a heavy contamination of Earth dirt and air. But surprisingly, the grit that is proving most problematic for the team at this point is a fine layer of lubricants and other craft-building materials that coated the samples. The coating was expected, but it is proving tricky to deal with.
Earth contamination can be separated from the samples mainly because the solar wind particles penetrated deep into the collector cells, a depth of approximately 40 nanometers.
The study of neon and argon was not affected as much by Earth contamination because dirt and air on Earth contain relatively little neon and argon.
The team remains hopeful that they will be able to get results on oxygen and nitrogen isotopes from the mission. To do this, they plan to examine a collecting dish that, although banged up and dirtied by the landing, seems to have succeeded in gathering up enough of these elements for measurement.
Scientists are interested in nitrogen because on the Moon, isotopes of this element vary greatly between the collected soil samples, even though all nitrogen is thought to come from the solar wind. Researchers want to know the reason for this variation.
Oxygen isotopes are even odder, as they seem to have unique ‘fingerprint’ values in different types of objects. For example if given a rock sample, scientists can measures oxygen isotopes and determine whether it is from Earth or space or the Moon. But put they are still trying to understand why. By knowing the value in the Sun, and hence the early Solar System, they expect to pin down the reason for this oddity.
Some are even confident that with more work and a few more years, they will also get oxygen and nitrogen.
To learn more about the Genesis mission, visit these websites:
http://www.nasa.gov/genesis
http://genesis.lanl.gov/
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MARS IS COMING, PART 4
As the December 24 opposition approaches, please enjoy this fourth installment on the Red Planet Mars.
The Atmosphere (Part 2)
Quick Atmospheric Temperature Overview:
- Surface: Cyclic temperatures range from approximately 189 K (-119 °F, -84 °C) to 240 K (-28 °F, -33 °C)
- Lower atmosphere: Altitude of a few kilometers up to 40 km (a few miles up to 25 miles). Temperature decreases at a rate of .5 K per km.
- Tropopause: 40 km to 100 km (25 miles to 60 miles).
- Above 100 km (above 60 miles): Average temperature of about 300 K (80 °F, 27 °C).
Atmospheric Constituents:
Below about 125 km (80 miles), the Martian atmosphere is composed of 95.5% carbon dioxide and small amounts of nitrogen, water vapor and argon, with trace amounts of other gases. To put some of these components in perspective, carbon dioxide is responsible for the Greenhouse Effect and is used for carbonation in beverages, nitrogen is a crucial element in DNA, and argon is used to make blue neon light blubs.
Atmospheric structure
Even though the Martian atmosphere is very thin by comparison to Earth’s, it is still very dynamic and very complex. The relation of temperature and pressure to the altitude--sometimes called the vertical structure of the atmosphere--is determined by two factors. One is a complicated balance of several mechanisms that spread energy through the atmosphere. The other is the way in which the sun's energy is introduced into the atmosphere and then lost by radiation to space.
In the lower atmosphere, the vertical structure is controlled by a combination of almost-pure carbon dioxide and the large amount of suspended dust. Carbon dioxide radiates energy efficiently at the colder (relative to Earth) Martian temperatures, so the atmosphere responds quickly to changes in the amount of solar radiation it receives. The suspended dust absorbs large quantities of heat directly from sunlight and distributes the energy throughout the lower atmosphere.
Like Earth, Martian surface temperatures depend on the latitude. But the temperatures fluctuate over a wider range from day to night. At the Viking 1 and Pathfinder landing sites, both of which are about 20° N latitude, the temperatures at roughly human height above the surface regularly varied from a low near 189 K (-119 °F, -84 °C) just before sunrise to a high of 240 K (-28 °F, -33 °C) in the early afternoon—an amazing range of about 51 K or 51 °C or 91 °F. This temperature swing is much greater than that of the desert regions on Earth. The variation is greatest very close to the ground where the thin, dry atmosphere allows the surface to radiate its heat quickly during the night. During dust storms this ability is restricted, and the temperature swing is reduced. At altitudes above a few kilometers, the daily variation is damped out, but other cyclic changes appear throughout the atmosphere because of the sun’s energy. The temperature and pressure cycles are sometimes called “tides” because they are regular, periodic, and synchronized with the position of the sun. These tides give the Martian atmosphere a very complex vertical structure.
Up to about 40 km (25 miles) the atmosphere gradually cools at a rate of .5 K per km.
Beginning at that level, called the tropopause, the temperature becomes a roughly constant 140 K (-210 °F, -130 °C). This was measured by the Viking and Pathfinder spacecraft as they descended through the atmosphere. Before these measurements were taken, scientists thought the tropopause began at about 15 km (9 miles), and the rate of temperature drop leading up to that altitude was thought to be near 5 K per km. The large amount of dust suspended in the atmosphere is thought to be responsible for the differences.
Above 100 km (60 miles), the structure of the atmosphere is determined by the tendency of the heavier molecules to settle below the lighter ones. This diffusive separation process overcomes the tendency of turbulence to mix all the constituents together. At these high altitudes, absorption of ultraviolet light from the sun dissociates and ionizes the gases and leads to complex sequences of chemical reactions. The top of the atmosphere has an average temperature of about 300 K (80 °F, 27 °C).
Meteorology and atmospheric dynamics
The global pattern of atmospheric circulation on Mars appears similar to that of Earth, but the root causes are very different. Among these differences are the atmosphere's ability to adjust rapidly to local conditions of solar heat input; the lack of oceans, which on Earth have a large resistance to temperature changes; the great range in altitude of the surface; the strong internal heating of the atmosphere because of suspended dust; and the seasonal deposition and release of a large part of the Martian atmosphere at the poles.
The only direct measurements of wind speeds were made by the Viking and Pathfinder landers. Near-surface winds at the landing sites were usually regular in behavior and generally light. Average speeds were typically less than 2 meters per second (4.5 miles per hour), although gusts up to 40 meters per second (90 miles per hour) were recorded. Other observations, including streaks of windblown dust and patterns in dune fields and in the many varieties of clouds, provide additional clues about surface winds.
Global circulation models, which incorporate all the factors understood to influence the behavior of the atmosphere, predict that the winds are strongly needed to create the Martian seasons because of the large horizontal temperature gradients associated with the edge of the polar caps in the fall and winter. Strong jet streams with eastward velocities above 100 meters per second (225 miles per hour) form at high latitudes in winter. Atmosphere circulation is less dramatic in spring and fall, when light winds predominate everywhere. On Mars, unlike on Earth, there is also a relatively strong north-south circulation that transports the atmosphere to and from the winter and summer poles. The general circulation pattern is occasionally unstable and exhibits large-scale wave motions and instabilities: a regular series of rotating high- and low-pressure systems was clearly seen in the pressure and wind records at the Viking lander sites.
Smaller-scale motions and circulations, driven both by the sun and by surface topography, are found everywhere. For example, at the Viking and Pathfinder landing sites, the winds change in direction and speed throughout the day in response to the position of the sun and the local slope of the land.
Turbulence is an important factor in raising and maintaining the large quantity of dust found in the atmosphere. Dust storms tend to begin at certain locations in the southern hemisphere during the southern spring and summer. Activity is at first local and strong (for reasons yet to be understood), and large amounts of dust are thrown high into the atmosphere. If the amount of dust reaches a critical quantity, the storm quickly intensifies, and dust is carried by high winds to all parts of the planet. In a few days the storm hides the entire surface, and visibility is reduced to less than 5 percent of normal. The strengthening process is short-lived and the atmosphere begins to clear almost immediately, becoming normal typically in a few weeks.
Next Time: "The Polar Caps"
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Nov 24, 9:30 AM EST - Full Moon. Called the "Beaver Moon" or "Snow Moon," this was the time to set beaver traps before the swamps froze, in order to ensure a supply of winter furs. Others suggest the name refers to the fact that beavers were actively preparing for winter. This full moon is also sometimes called the "Frosty Moon."
Nov 24 – The planet Uranus is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
Nov 27 – The planet Mars is 1.7° south of the Moon
Nov 28 – The planet Venus is 4° north of the star Spica
Nov 30 - the star Regulus 0.3° north of the Moon, an occultation as seen from some locations. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Dec 1, 7:44 A.M. EST - Last Quarter Moon
Dec 1 – The planet Saturn is 2° north of Moon
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SPACE EXPLORATION THIS WEEK
Nov 30 - Ulysses, begins its third north polar pass of the sun
****************************************
THIS WEEK IN HISTORY
Nov 26, 1965 - Asterix 1 Launch, France's 1st Satellite Launch
Nov 26, 1999 - Discovery of SAU 005 & 008, two Mars Meteorites
Nov 27, 1701 - Birthday of Anders Celsius, Swedish astronomer (1701-1744). Celsius developed a thermometer which had 100 points between the freezing point (100) and boiling point (0) of water. The scale was later reversed by Carolus Linnaeus so that the freezing point was 0 and the boiling point was 100. This temperature scale is named in his honor.
Nov 27, 1971 - Mars 2, Mars Orbit Insertion
Nov 28, 1700 - Birthday of Nathaniel Bliss, British astronomer, succeeded James Bradley to be the fourth Astronomer Royal, serving from 1762 until his death in 1764.
Nov 28, 1964 - Mariner 4 Launch, Mars Flyby Mission
Nov 29, 1961 - Mercury 5 Launch with Enos the Chimpanzee
Nov 29, 1967 - Wresat 1 Launch, Australia's 1st Satellite, 40th Anniversary
Nov 29, 2000 - Discovery of Y000593 Meteorite, a Mars Meteorite
Nov 30, 1954 - Sylacauga Meteorite Fall, Hit Woman
Dec ??, 2000 - Discovery of NWA 817 Meteorite, a Mars Meteorite
Dec 1, 1960 - Sputnik 6 Launch, Carried Two Dogs: Pchelka & Mushka
****************************************
MUSICAL DIVERSION
According to a 1580 entry in the Stationers’ Register, license was given to a Richard Jones to print “A new Northern Dittye of the Lady Green-Sleeves.” This was one of the first references to the song known today as “Greensleeves.” The other reference appeared the same year, by Edward White, entitled "A ballad, being the Ladie Greene Sleeves Answere to Donkyn his frende." The earliest surviving lyrics are in a collection called A Handful of Pleasant Delights (1584). The actual “Greensleeves” tune first appeared in 1652.
Many stories have developed around the song. According to legend, King Henry VIII of England (1491-1547) wrote the song for Anne Boleyn during their courtship, around 1530. However, this has never been proven and is probably not true. But it is also said that Henry’s daughter Queen Elizabeth I danced to the song. The song’s tune was used as the basis for a number of other lyrics, including a political ballad of the day. Even William Shakespeare mentioned “Greensleeves” twice (in Act Two and Act Five) in his play, “The Merry Wives of Windsor.”
The lyrics show the song to be a plea from a 16th century gentleman to his bored mistress. Here are some of the recorded lyrics for the song.
Greensleeves
Alas, my love you do me wrong
To cast me off discourteously
And I have loved you so long
Delighting in your company
Chorus:
Greensleeves was all my joy
Greensleeves was my delight
Greensleeves was my heart of gold
And who but my Lady Greensleeves.
I have been ready at your hand
to grant whatever you would crave;
I have both wagered life and land
Your love and good will for to have
(chorus)
I bought the kerchers to thy head
That were wrought fine and gallantly
I kept thee both at board and bed
Which cost my purse well favouredly.
(chorus)
Greensleeves, now farewell! adieu!
God I pray to prosper thee;
For I am still thy lover true
Come once again and love me.
(chorus)
-----
One of the tune’s early appearances in a hymn was entitled “The Old Yeare Now Away Is Fled.” Then about 1865, English poet and lay theologian William Chatterton Dix published a poem entitled "The Manger Throne." Dix was already known for other carols, including "As With Gladness Men of Old" (1859). Portions of Dix’s new poem were later adapted for the tune "Greensleeves," creating the carol that we know as "What Child Is This?" It is not known who combined the words with the tune, but it may have been John Stainer (1840-1901), since Stainer wrote a harmonization for the song. Stainer published the song in his 1871 collection entitled Christmas Carols New and Old. Below is the text from that publication.
What Child Is This
What Child is this who, laid to rest
On Mary’s lap is sleeping?
Whom angels greet with anthems sweet,
While shepherds watch are keeping?
Chorus:
This, this is Christ the King,
Whom shepherds guard and angels sing;
Haste, haste, to bring Him laud,
The Babe, the Son of Mary.
Why lies He in such mean estate,
Where ox and ass are feeding?
Good Christians, fear, for sinners here
The silent Word is pleading.
Chorus:
Nails, spear shall pierce Him through,
The cross be borne for me, for you.
Hail, hail the Word made flesh,
The Babe, the Son of Mary.
So bring Him incense, gold and myrrh,
Come peasant, king to own Him;
The King of kings salvation brings,
Let loving hearts enthrone Him.
Chorus:
Raise, raise a song on high,
The virgin sings her lullaby.
Joy, joy for Christ is born,
The Babe, the Son of Mary.
-----
To review some the history, the text, or to listen to the melody, check out this pages from the "Songs of England" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/england/grenslevs.html
To see and hear more on the hymn, “"What Child Is This?" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/h/whatcist.htm
The goal of NASA's Genesis mission was to collect samples of the solar wind and return them to Earth for study. The Genesis spacecraft spent 27 months in space, gathering tiny particles from different types of solar wind. It then returned to Earth and ejected its sealed sample capsule for Earth re-entry and a gentle airborne recovery by helicopter. Unfortunately the planned parachute-capture of the capsule was not possible because the parachute failed to deploy. The sad result was the creation of a new small crater in the Utah desert. Observers of the crash were initially devastated, but the mission team soon realized that data could still be salvaged, though more slowly and with more effort.
The results, picked from millimeter-sized shards of the spacecraft's detectors, provide a snapshot of the early solar system, and will feed into models that outline how our planet’s atmosphere evolved.
The team originally hoped they could publish a series of papers within a year of the return. It has taken much longer, but as of late October a series of four papers had been published in Space Science Reviews and a fifth paper appeared the week of October 14 in Science. In addition, a preliminary paper was published last year.
The team remains hopeful that they will soon be able to complete the main goal of their original mission: solving the mystery of the unique isotopic signature of different objects in our galaxy.
The recent paper in Science contains a study of the ratio of different isotopes of neon and argon obtained from samples of three types of solar wind: fast, slow, and coronal mass ejections from the sun’s surface. The researchers conclude that these ratios are essentially the same in all three types of wind. This is good news: it indicates that the elements of main interest to the researchers have the same isotopic signature in the solar wind as in the sun itself.
That’s useful because the outer layer of the sun is thought to provide a picture of isotopic ratios in the very early solar system, before stars or planets were formed. Scientists had previously been concern that there would be a difference between the compositions of the solar wind and the sun itself.
The isotopic ratios of neon and argon are not in themselves very surprising — scientists already had a fairly good measure of these values from previous missions, including one low-tech scheme during the Apollo program in which a screen was laid out on the Moon to collect solar-wind samples. But they improve by a factor of 60 the precision with which the argon isotope ratio is known. This will be useful for researchers who model the early solar system to work out processes such as how Earth’s atmosphere formed.
As expected, the Genesis samples have a heavy contamination of Earth dirt and air. But surprisingly, the grit that is proving most problematic for the team at this point is a fine layer of lubricants and other craft-building materials that coated the samples. The coating was expected, but it is proving tricky to deal with.
Earth contamination can be separated from the samples mainly because the solar wind particles penetrated deep into the collector cells, a depth of approximately 40 nanometers.
The study of neon and argon was not affected as much by Earth contamination because dirt and air on Earth contain relatively little neon and argon.
The team remains hopeful that they will be able to get results on oxygen and nitrogen isotopes from the mission. To do this, they plan to examine a collecting dish that, although banged up and dirtied by the landing, seems to have succeeded in gathering up enough of these elements for measurement.
Scientists are interested in nitrogen because on the Moon, isotopes of this element vary greatly between the collected soil samples, even though all nitrogen is thought to come from the solar wind. Researchers want to know the reason for this variation.
Oxygen isotopes are even odder, as they seem to have unique ‘fingerprint’ values in different types of objects. For example if given a rock sample, scientists can measures oxygen isotopes and determine whether it is from Earth or space or the Moon. But put they are still trying to understand why. By knowing the value in the Sun, and hence the early Solar System, they expect to pin down the reason for this oddity.
Some are even confident that with more work and a few more years, they will also get oxygen and nitrogen.
To learn more about the Genesis mission, visit these websites:
http://www.nasa.gov/genesis
http://genesis.lanl.gov/
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MARS IS COMING, PART 4
As the December 24 opposition approaches, please enjoy this fourth installment on the Red Planet Mars.
The Atmosphere (Part 2)
Quick Atmospheric Temperature Overview:
- Surface: Cyclic temperatures range from approximately 189 K (-119 °F, -84 °C) to 240 K (-28 °F, -33 °C)
- Lower atmosphere: Altitude of a few kilometers up to 40 km (a few miles up to 25 miles). Temperature decreases at a rate of .5 K per km.
- Tropopause: 40 km to 100 km (25 miles to 60 miles).
- Above 100 km (above 60 miles): Average temperature of about 300 K (80 °F, 27 °C).
Atmospheric Constituents:
Below about 125 km (80 miles), the Martian atmosphere is composed of 95.5% carbon dioxide and small amounts of nitrogen, water vapor and argon, with trace amounts of other gases. To put some of these components in perspective, carbon dioxide is responsible for the Greenhouse Effect and is used for carbonation in beverages, nitrogen is a crucial element in DNA, and argon is used to make blue neon light blubs.
Atmospheric structure
Even though the Martian atmosphere is very thin by comparison to Earth’s, it is still very dynamic and very complex. The relation of temperature and pressure to the altitude--sometimes called the vertical structure of the atmosphere--is determined by two factors. One is a complicated balance of several mechanisms that spread energy through the atmosphere. The other is the way in which the sun's energy is introduced into the atmosphere and then lost by radiation to space.
In the lower atmosphere, the vertical structure is controlled by a combination of almost-pure carbon dioxide and the large amount of suspended dust. Carbon dioxide radiates energy efficiently at the colder (relative to Earth) Martian temperatures, so the atmosphere responds quickly to changes in the amount of solar radiation it receives. The suspended dust absorbs large quantities of heat directly from sunlight and distributes the energy throughout the lower atmosphere.
Like Earth, Martian surface temperatures depend on the latitude. But the temperatures fluctuate over a wider range from day to night. At the Viking 1 and Pathfinder landing sites, both of which are about 20° N latitude, the temperatures at roughly human height above the surface regularly varied from a low near 189 K (-119 °F, -84 °C) just before sunrise to a high of 240 K (-28 °F, -33 °C) in the early afternoon—an amazing range of about 51 K or 51 °C or 91 °F. This temperature swing is much greater than that of the desert regions on Earth. The variation is greatest very close to the ground where the thin, dry atmosphere allows the surface to radiate its heat quickly during the night. During dust storms this ability is restricted, and the temperature swing is reduced. At altitudes above a few kilometers, the daily variation is damped out, but other cyclic changes appear throughout the atmosphere because of the sun’s energy. The temperature and pressure cycles are sometimes called “tides” because they are regular, periodic, and synchronized with the position of the sun. These tides give the Martian atmosphere a very complex vertical structure.
Up to about 40 km (25 miles) the atmosphere gradually cools at a rate of .5 K per km.
Beginning at that level, called the tropopause, the temperature becomes a roughly constant 140 K (-210 °F, -130 °C). This was measured by the Viking and Pathfinder spacecraft as they descended through the atmosphere. Before these measurements were taken, scientists thought the tropopause began at about 15 km (9 miles), and the rate of temperature drop leading up to that altitude was thought to be near 5 K per km. The large amount of dust suspended in the atmosphere is thought to be responsible for the differences.
Above 100 km (60 miles), the structure of the atmosphere is determined by the tendency of the heavier molecules to settle below the lighter ones. This diffusive separation process overcomes the tendency of turbulence to mix all the constituents together. At these high altitudes, absorption of ultraviolet light from the sun dissociates and ionizes the gases and leads to complex sequences of chemical reactions. The top of the atmosphere has an average temperature of about 300 K (80 °F, 27 °C).
Meteorology and atmospheric dynamics
The global pattern of atmospheric circulation on Mars appears similar to that of Earth, but the root causes are very different. Among these differences are the atmosphere's ability to adjust rapidly to local conditions of solar heat input; the lack of oceans, which on Earth have a large resistance to temperature changes; the great range in altitude of the surface; the strong internal heating of the atmosphere because of suspended dust; and the seasonal deposition and release of a large part of the Martian atmosphere at the poles.
The only direct measurements of wind speeds were made by the Viking and Pathfinder landers. Near-surface winds at the landing sites were usually regular in behavior and generally light. Average speeds were typically less than 2 meters per second (4.5 miles per hour), although gusts up to 40 meters per second (90 miles per hour) were recorded. Other observations, including streaks of windblown dust and patterns in dune fields and in the many varieties of clouds, provide additional clues about surface winds.
Global circulation models, which incorporate all the factors understood to influence the behavior of the atmosphere, predict that the winds are strongly needed to create the Martian seasons because of the large horizontal temperature gradients associated with the edge of the polar caps in the fall and winter. Strong jet streams with eastward velocities above 100 meters per second (225 miles per hour) form at high latitudes in winter. Atmosphere circulation is less dramatic in spring and fall, when light winds predominate everywhere. On Mars, unlike on Earth, there is also a relatively strong north-south circulation that transports the atmosphere to and from the winter and summer poles. The general circulation pattern is occasionally unstable and exhibits large-scale wave motions and instabilities: a regular series of rotating high- and low-pressure systems was clearly seen in the pressure and wind records at the Viking lander sites.
Smaller-scale motions and circulations, driven both by the sun and by surface topography, are found everywhere. For example, at the Viking and Pathfinder landing sites, the winds change in direction and speed throughout the day in response to the position of the sun and the local slope of the land.
Turbulence is an important factor in raising and maintaining the large quantity of dust found in the atmosphere. Dust storms tend to begin at certain locations in the southern hemisphere during the southern spring and summer. Activity is at first local and strong (for reasons yet to be understood), and large amounts of dust are thrown high into the atmosphere. If the amount of dust reaches a critical quantity, the storm quickly intensifies, and dust is carried by high winds to all parts of the planet. In a few days the storm hides the entire surface, and visibility is reduced to less than 5 percent of normal. The strengthening process is short-lived and the atmosphere begins to clear almost immediately, becoming normal typically in a few weeks.
Next Time: "The Polar Caps"
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
****************************************
THE SKY THIS WEEK
Nov 24, 9:30 AM EST - Full Moon. Called the "Beaver Moon" or "Snow Moon," this was the time to set beaver traps before the swamps froze, in order to ensure a supply of winter furs. Others suggest the name refers to the fact that beavers were actively preparing for winter. This full moon is also sometimes called the "Frosty Moon."
Nov 24 – The planet Uranus is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
Nov 27 – The planet Mars is 1.7° south of the Moon
Nov 28 – The planet Venus is 4° north of the star Spica
Nov 30 - the star Regulus 0.3° north of the Moon, an occultation as seen from some locations. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Dec 1, 7:44 A.M. EST - Last Quarter Moon
Dec 1 – The planet Saturn is 2° north of Moon
****************************************
SPACE EXPLORATION THIS WEEK
Nov 30 - Ulysses, begins its third north polar pass of the sun
****************************************
THIS WEEK IN HISTORY
Nov 26, 1965 - Asterix 1 Launch, France's 1st Satellite Launch
Nov 26, 1999 - Discovery of SAU 005 & 008, two Mars Meteorites
Nov 27, 1701 - Birthday of Anders Celsius, Swedish astronomer (1701-1744). Celsius developed a thermometer which had 100 points between the freezing point (100) and boiling point (0) of water. The scale was later reversed by Carolus Linnaeus so that the freezing point was 0 and the boiling point was 100. This temperature scale is named in his honor.
Nov 27, 1971 - Mars 2, Mars Orbit Insertion
Nov 28, 1700 - Birthday of Nathaniel Bliss, British astronomer, succeeded James Bradley to be the fourth Astronomer Royal, serving from 1762 until his death in 1764.
Nov 28, 1964 - Mariner 4 Launch, Mars Flyby Mission
Nov 29, 1961 - Mercury 5 Launch with Enos the Chimpanzee
Nov 29, 1967 - Wresat 1 Launch, Australia's 1st Satellite, 40th Anniversary
Nov 29, 2000 - Discovery of Y000593 Meteorite, a Mars Meteorite
Nov 30, 1954 - Sylacauga Meteorite Fall, Hit Woman
Dec ??, 2000 - Discovery of NWA 817 Meteorite, a Mars Meteorite
Dec 1, 1960 - Sputnik 6 Launch, Carried Two Dogs: Pchelka & Mushka
****************************************
MUSICAL DIVERSION
According to a 1580 entry in the Stationers’ Register, license was given to a Richard Jones to print “A new Northern Dittye of the Lady Green-Sleeves.” This was one of the first references to the song known today as “Greensleeves.” The other reference appeared the same year, by Edward White, entitled "A ballad, being the Ladie Greene Sleeves Answere to Donkyn his frende." The earliest surviving lyrics are in a collection called A Handful of Pleasant Delights (1584). The actual “Greensleeves” tune first appeared in 1652.
Many stories have developed around the song. According to legend, King Henry VIII of England (1491-1547) wrote the song for Anne Boleyn during their courtship, around 1530. However, this has never been proven and is probably not true. But it is also said that Henry’s daughter Queen Elizabeth I danced to the song. The song’s tune was used as the basis for a number of other lyrics, including a political ballad of the day. Even William Shakespeare mentioned “Greensleeves” twice (in Act Two and Act Five) in his play, “The Merry Wives of Windsor.”
The lyrics show the song to be a plea from a 16th century gentleman to his bored mistress. Here are some of the recorded lyrics for the song.
Greensleeves
Alas, my love you do me wrong
To cast me off discourteously
And I have loved you so long
Delighting in your company
Chorus:
Greensleeves was all my joy
Greensleeves was my delight
Greensleeves was my heart of gold
And who but my Lady Greensleeves.
I have been ready at your hand
to grant whatever you would crave;
I have both wagered life and land
Your love and good will for to have
(chorus)
I bought the kerchers to thy head
That were wrought fine and gallantly
I kept thee both at board and bed
Which cost my purse well favouredly.
(chorus)
Greensleeves, now farewell! adieu!
God I pray to prosper thee;
For I am still thy lover true
Come once again and love me.
(chorus)
-----
One of the tune’s early appearances in a hymn was entitled “The Old Yeare Now Away Is Fled.” Then about 1865, English poet and lay theologian William Chatterton Dix published a poem entitled "The Manger Throne." Dix was already known for other carols, including "As With Gladness Men of Old" (1859). Portions of Dix’s new poem were later adapted for the tune "Greensleeves," creating the carol that we know as "What Child Is This?" It is not known who combined the words with the tune, but it may have been John Stainer (1840-1901), since Stainer wrote a harmonization for the song. Stainer published the song in his 1871 collection entitled Christmas Carols New and Old. Below is the text from that publication.
What Child Is This
What Child is this who, laid to rest
On Mary’s lap is sleeping?
Whom angels greet with anthems sweet,
While shepherds watch are keeping?
Chorus:
This, this is Christ the King,
Whom shepherds guard and angels sing;
Haste, haste, to bring Him laud,
The Babe, the Son of Mary.
Why lies He in such mean estate,
Where ox and ass are feeding?
Good Christians, fear, for sinners here
The silent Word is pleading.
Chorus:
Nails, spear shall pierce Him through,
The cross be borne for me, for you.
Hail, hail the Word made flesh,
The Babe, the Son of Mary.
So bring Him incense, gold and myrrh,
Come peasant, king to own Him;
The King of kings salvation brings,
Let loving hearts enthrone Him.
Chorus:
Raise, raise a song on high,
The virgin sings her lullaby.
Joy, joy for Christ is born,
The Babe, the Son of Mary.
-----
To review some the history, the text, or to listen to the melody, check out this pages from the "Songs of England" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/england/grenslevs.html
To see and hear more on the hymn, “"What Child Is This?" visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/h/whatcist.htm
Sunday, November 18, 2007
WEEKLY UPDATE
Astronomer Questions Significance of COBE Images
Most astronomers say the Cosmic Background Explorer (COBE) satellite images show structures of the early universe. But 70-year-old radio astronomer and author Gerrit Verschuur of the University of Memphis, claims to have evidence that the images actually depict nearby hydrogen gas clouds in our own galaxy, calling into question one of the most important theories in the past 15 years. Verschuur's research will be published December 10 in the Astrophysical Journal.
NASA scientists announced in 1992 that their COBE satellite had imaged the ultimate baby pictures of the universe, revealing the seeds that grew into galaxies like our own Milky Way. And in 2003, higher-resolution images of the seeds were taken by another satellite, the Wilkinson Microwave Anisotropy Probe (WMAP).
According to Verschuur's research, the imaged seeds are located not on the edge of the universe, but nearby. Instead, they're just previously unmapped clouds of "neutral hydrogen" gas located inside the Milky Way. Verschuur sites at least 200 instances where the so-called cosmic seeds lie suspiciously close to known hydrogen clouds inside our galaxy.
Scientists who have reviewed his work suggest Verschuur’s correlations between the WMAP seeds and galactic hydrogen filaments are just coincidences. But as history has shown with previous debates over statistical interpretations, it is likely that Verschuur’s claim will not be settled anytime soon.
To learn more about the Cosmic Background Explorer (COBE) mission, visit the NASA website:
http://lambda.gsfc.nasa.gov/product/cobe/
Wilkinson Microwave Anisotropy Probe (WMAP) mission, visit the NASA website:
http://map.gsfc.nasa.gov/
Hubble Images Do Not Explain Comet 17P/Holmes Outburst
Astronomers are still uncertain what caused the brightening of normally-dim Comet 17P/Holmes, which erupted October 24 and is still shining brightly like a new star in the constellation Perseus.
In a November 15 announcement, three new comet images taken by the Hubble Space Telescope (HST) showed the core of Holmes as a field of particles extending some 15,000 miles across. The images also show that the particles appear to be coming from around the comet's hidden nucleus. This information, combined with another image taken by a ground-based telescope at the Calgary Science Centre (CSC) in Alberta, Canada, supplements the idea of some scientists that something must have broken off from around the nucleus and then disintegrated to become the dust cloud.
According to astronomers, the most likely explanation for the outburst is that a coating of relatively stable water ice, less than 10 miles thick around the comet's nucleus, was suddenly blown away by other, far more volatile chemical ices beneath the frozen water. As those ices heated and expanded violently, they blew the outer ice apart.
The new HST images show no large fragments in the cloud of particles that might suggest they were fragments of the nucleus itself or debris from a collision with a boulder-size asteroid orbiting between Mars and Jupiter - although some astronomers already have proposed that idea.
Seven years ago, HST imaged Comet Holmes, then nearly 150 million miles away. Astronomers inferred from the comet's brightness that its nucleus of rock and ice was barely more than 2 miles wide and that no dust obscured it. But the three new HST images have identified the 15,000-mile core of particles closest to the nucleus.
In addition, the new CSC image shows that at its brightest, the comet's particles extend for at least 2 million miles, with a thinner scattering of particles on its lower right side that may be the beginning of a comet tail.
When British amateur astronomer Edwin Holmes discovered the comet in November of 1892, he detected it because it had suddenly burst into a huge ball of light in his telescope. It then dimmed and, 73 days later, flared up briefly again.
At the time, U.S. astronomer Fred Whipple suggested that the flare-ups occurred because the comet had a double nucleus. Whipple proposed that one nucleus hit the other in a "grazing collision" that triggered the comet's first brilliant cloud of gas and dust, and then a full head-on crash 73 days later created the spectacular second outburst. In recalling Holmes' discovery, some will be watching in mid-January, hoping for a second display.
Still others suggest this year's flare-up might have resulted from a fragile nucleus spinning so fast that it just flew apart.
Astronomers at the Space Telescope Science Institute are studying the feasibility of a 2015 NASA mission to Comet Holmes or some other comet that has a history of flare-ups, and to orbit it long enough to learn the cause and maybe return a sample of the particles.
To learn more, visit Hubble Site, home of NASA's Hubble Space Telescope: http://hubblesite.org/
To learn more about the Calgary Science Centre in Alberta, Canada, visit their website: http://www.calgaryscience.ca/
****************************************
MARS IS COMING, PART 3
As the December 24 opposition approaches, please enjoy this third installment on the Red Planet Mars.
The Atmosphere (Part 1)
In 1947, Dutch-American astronomer Gerard P. Kuiper (1905-1973) determined from telescopic observations that the Martian atmosphere is composed mainly of carbon dioxide. The atmosphere is very thin, pushing at less than 1 percent of Earth's atmospheric pressure at the surface. The altitude varies greatly over the Martian surface, causing surface pressures to range over a factor of 15. Today's atmosphere has only small amounts of water. If it all was extracted and frozen, it would form a layer of ice crystals only 10 micrometers (0.0004 inch) thick, which could be gathered into a solid block of ice not much larger than one of Earth's medium-size icebergs. Geologic evidence suggests that in the distant past the atmosphere was much denser and water was much more abundant at the surface.
The average temperature in the lower atmosphere is about 200 kelvins (K; -100 °F, -70 °C), which is generally colder than the average daytime surface temperature of 250 K (-10 °F, -20 °C). These values are in the same range as those on Earth in Antarctica during winter. In summer above a very dark surface, daytime temperatures at the height of a human can peak at about 290 K (62 °F, 17 °C). Above the turbulent layer close to the surface, temperature decreases with elevation at a rate of about 1.5 K (2.7 °F, 1.5 °C) per km (about 2.4 K [4.3 °F, 2.4 °C] per mile) of altitude.
Unlike that of Earth, the atmosphere of Mars has large seasonal variations in pressure. During each hemisphere’s winter, the main component, carbon dioxide, “snows out” over the winter pole. And during each hemisphere’s spring, the carbon dioxide returns directly to a gas (sublimes). Because the southern winter cap is larger than the northern, atmospheric pressure reaches a minimum during southern winter when the southern cap is at its largest. From Viking lander measurements of the pressure, which was found to vary by 26 percent annually over the mean, scientists calculated that some 7.9 trillion metric tons of carbon dioxide leave and reenter the atmosphere seasonally. This is equivalent to a thickness of at least 23 cm (9 inches) of solid carbon dioxide (dry ice) or several meters of carbon dioxide snow averaged over the vast area of the seasonal polar caps.
Direct chemical analysis at the surface by the Viking landers and spectral observations from orbiting spacecraft allowed scientists to precisely determine the composition of the atmosphere. Where the atmosphere is well mixed by turbulence—below an altitude of 125 km (about 80 miles)—95.3 percent of the atmosphere by weight is carbon dioxide (see the table). This is a comparatively large amount—nine times the quantity now in Earth's much more massive atmosphere. Much of Earth's carbon dioxide, however, is chemically locked in sedimentary rocks; the amount in the Martian atmosphere is less than a thousandth of the terrestrial total. The balance of the Martian atmosphere consists of molecular nitrogen, water vapor, and noble gases (argon, neon, krypton, and xenon). There are also trace amounts of gases that have been produced from the primary constituents by photochemical reactions, generally high in the atmosphere; these include molecular oxygen, carbon monoxide, nitric oxide, and small amounts of ozone.
The lower atmosphere supplies gas to the planet's ionosphere, where densities are low, temperatures are high, and components separate by diffusion according to their masses. Various constituents in the top of the atmosphere are lost to space, which affects the isotopic composition of the remaining gases. For example, because hydrogen is lost preferentially over its heavier isotope deuterium, Mars's atmosphere contains five times more deuterium than Earth's.
Although water is only a minor constituent of the Martian atmosphere (a few molecules per 10,000 at most), primarily because of low atmospheric and surface temperatures, it plays an important role in atmospheric chemistry and meteorology. The Martian atmosphere is effectively saturated with water vapor, yet there is no liquid water present on the surface. The temperature and pressure of the planet are so low that water molecules can exist only as ice or as vapor. Little water is exchanged daily with the surface despite the very cold nighttime surface temperatures.
Most of the information about atmospheric water on Mars has come from the Viking orbiters, which observed seasonal patterns of water content in the atmosphere over a full Martian year. Water vapor is mixed uniformly up to altitudes of 10–15 km (6–9 miles) and shows strong latitudinal gradients that depend on the season. The largest changes occur in the northern hemisphere. During summer in the north, the complete disappearance of the carbon dioxide cap leaves behind a water-ice cap. Sublimation of water from the residual cap results in a strong north-to-south concentration gradient of water vapor in the atmosphere. In the south, where a small carbon dioxide cap remains in summer and only a small amount of water ice has been detected, a strong water vapor gradient does not normally develop in the atmosphere.
The atmospheric water vapor is thought to be in contact with a much larger reservoir in the Martian soil. Subsurface layers of ice are thought to be ubiquitous on Mars at latitudes between 40° and the poles; the very low subsurface temperatures would prevent the ice from subliming. The 2001 Mars Odyssey spacecraft, which began orbital observations of the planet in late 2001, confirmed that ice is present within a meter of the surface at these latitudes, but it is not known how deep the ice layer extends. In contrast, at low latitudes, ice is unstable, and any ice present in the ground would tend to sublime into the atmosphere.
The Viking landers' analytical instruments also measured the isotopic composition of the major and minor atmospheric gases. The similarity of the ratios of isotopes of carbon and oxygen to their terrestrial values implies that large reservoirs of carbon dioxide and water ice exist on Mars and that gases from the reservoirs exchange with those in the atmosphere. The results of other isotopic measurements from Viking suggest that larger amounts of carbon dioxide, nitrogen, and argon were present in the atmosphere in the past and that Mars may have lost much of its inventory of volatile substances early in its history, either to space or to the ground (i.e., locked up chemically in rocks). Some scientists have conjectured that Mars may once have had a much thicker atmosphere but that it was lost to the surface through chemical reactions, which formed carbonates, and to space through large asteroid impacts, which blew off atmospheric gases.
Next Time: “The Atmosphere, Part 2”
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
****************************************
THE SKY THIS WEEK
Nov 17, 5:33 PM EST - First Quarter Moon
Nov 17 - Neptune is 1.0° north of Moon, occultation. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Nov 17 - Leonid meteors
Nov 19 - Uranus is 2° south of Moon
Nov 23 - Moon is at perigee, the point in the Moon's orbit when it is closest from Earth.
Nov 24, 9:30 AM EST - Full Moon. Called the “Beaver Moon” or “Snow Moon,” this was the time to set beaver traps before the swamps froze, in order to ensure a supply of winter furs. Others suggest the name refers to the fact that beavers were actively preparing for winter. This full moon is also sometimes called the “Frosty Moon.”
Nov 24 - Uranus is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
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THIS WEEK IN HISTORY
Nov 18, 1989 – Launch of The Cosmic Background Exporer satellite (COBE)
Nov 20, 1889 – Birthday of Edwin Hubble
Nov 20, 2004 - Mars Rover “Spirit” landing on Mars
****************************************
MUSICAL DIVERSION
The Dutch folk song "Wilder dan wilt" (Wilder than wild) has been traced back at least to the late 1500s. The song began "Wilder dan wilt, wie sal mij temmen," or "Wilder than wild, who will tame me?" Here are the verses.
Wilder Dan Wilt
Wilder dan wildt, wie sal my temmen,
plach ick te singhen vroech ende laet;
ick heb geluystert na Christi stemmen,
die heeft my getrocken tot anderen staet.
Ick was soo wilt, 't mocht aen my blijcken,
als eenen voghel vliecht in de locht;
Heer Jesus heeft my met sijn practijcken
soo soetkens al in sijn net ghebrocht.
Vry, liber, en los, en onghebonden,
mijn willeken volchde ick over al;
dat heeft my doen vallen in soo veel sonden,
het welck ick met recht beklaghen sal.
Heer Jesus leert my mijn willeken breken,
al vallet my somtijdts hert en swaer;
daer door kan ick veel quaedts versteken,
in alles gherust volgh' ick hem naer.
Ick plach te gaen proncken lancks de straten,
verciert als een goddinneken ient;
heer Jesus heeft my dit doen verlaten,
mijn kruysken opnemen, dat hy my sent.
Cupido begon my heel te minnen
en te bestralen met sijn venijn;
nu leer ick aen Jesum vast leggen mijn sinnen,
om gracy te vinden voor sijn aenschijn.
Voor 't slempen, en dempen, en triomferen,
oock danssen en springhen met herten bly,
moet'ick nu vasten en abstineren;
mijnen tijdt beschreyen, is mijn party.
O Prince, ick wacht mijn recompence,
als ghy sult oordeelen in den troon;
dat ick dan hooren mach die sentence:
‘komt hier mijn bruydt, ontfanght de kroon.’
-----
Some have suggested this was a bawdy song, but a quick scan of the Dutch lyrics and a rough translation here and there will show several references to "Lord Jesus" and "Christ" and "my sin." Such an observation will tell you this was more of a hymn than a tavern song. The tune may be even older than these words. Whatever the case, it seems apparent that the tune was well known because it was later set to other Dutch lyrics. On January 24, 1597 at the Battle of Turnhout, the Dutch Prince Maurice of Orange defeated Spanish occupiers of a region that is now part of the Netherlands. The Dutch Protestants, who had been forbidden to practice their faith under the Catholic King Philip II of Spain, rejoiced through new hymns that celebrated their victory. On such hymn was written by a poet and writer of songs named Adriaen Valéry, who wrote under Latinized name Adrianus Valerius (1575-1625). He actually wrote this new hymn during the year of the Dutch Protestant victory, but it was not widely published until the year after Valéry's death. We can thank his son François for publishing his collecton, entitled "Nederlandtsche Gedenckclanck." The hymn was entitled “Wilt Heden Nu Treden.”
Wilt Heden Nu Treden
Wilt heden nu treden voor God, den Heere,
Hem boven al loven van harte zeer,
En maken groot zijns lieven namens eere,
Die daar nu onzen vijand slaat terneer.
Ter eeren ons Heeren wilt al uw dagen
Dit wonder bijzonder gedenken toch.
Maakt u, o mensch, voor God steeds wel te dragen,
Doet ieder recht en wacht u voor bedrog!
Bidt, waket en maket, dat g'in bekoring
En 't kwade met schade toch niet en valt.
Uw vroomheid brengt den vijand tot verstoring,
Al waar' zijn rijk nog eens zoo sterk bewald!
-----
In 1877, the German chorus master Eduard Kremser (1838-1914) published a translation of the lyrics from Dutch to Latin along with an arrangement of the tune for chorus and orchestra. From that point, the tune became known to many simply as “Kremser.” A few years later, in 1894, the text was loosely translated to English by U.S.-born musical scholar Theodore Baker (1851-1934). Some of the militant flavor of the original was lost, but essence of the text remained. He called the hymn “We Gather Together.”
We Gather Together
We gather together to ask the Lord’s blessing;
He chastens and hastens His will to make known.
The wicked oppressing now cease from distressing.
Sing praises to His Name; He forgets not His own.
Beside us to guide us, our God with us joining,
Ordaining, maintaining His kingdom divine;
So from the beginning the fight we were winning;
Thou, Lord, were at our side, all glory be Thine!
We all do extol Thee, Thou Leader triumphant,
And pray that Thou still our Defender will be.
Let Thy congregation escape tribulation;
Thy Name be ever praised! O Lord, make us free!
-----
This hymn has become for many an important part of their annual Thanksgiving Day celebrations. And then in 1902, J. Archer Gibson, the organist of the Brick Presbyterian Church in New York City, approached active church member Mrs. Julia B. Cory (1882-1963) with a request for a new setting to the tune. For her inspiration, Cory returned to Valéry’s original hymn text. The new hymn was premiered on the very next Thanksgiving Day, and it was first published in “Hymns of the Living Church” in 1910. Cory called her hymn “We Praise Thee, O God, Our Redeemer, Creator.”
We Praise Thee, O God, Our Redeemer, Creator
We praise Thee, O God, our Redeemer, Creator,
In grateful devotion our tribute we bring;
We lay it before Thee, we kneel and adore Thee,
We bless Thy holy Name, glad praises we sing.
We worship Thee, God of our fathers, we bless Thee;
Through life’s storm and tempest our guide have Thou been;
When perils overtake us, escape Thou will make us,
And with Thy help, O Lord, our battles we win.
With voices united our praises we offer,
To Thee, great Jehovah, glad anthems we raise.
Thy strong arm will guide us, our God is beside us,
To Thee, our great Redeemer, forever be praise.
(Cory later added this Christmas stanza)
Thy love Thou didst show us, Thine only Son sending,
Who came as a Babe and Whose bed was a stall,
His blest life He gave us and then died to save us;
We praise Thee, O Lord, for Thy gift to us all.
-----
To view the lyrics of “Wilder Dan Wilt” visit this link - http://www.dbnl.org/tekst/duys001oude03_01/duys001oude03_01_0169.htm
To see and hear more on the hymn, “Wilt Heden Nu Treden” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/non/nl/wilthede.htm
To see and hear more on the hymn, “We Gather Together” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/e/wegattog.htm
To see and hear more on the hymn, “We Praise Thee, O God, Our Redeemer, Creator” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/p/wptogorc.htm
****************************************
Astronomer Questions Significance of COBE Images
Most astronomers say the Cosmic Background Explorer (COBE) satellite images show structures of the early universe. But 70-year-old radio astronomer and author Gerrit Verschuur of the University of Memphis, claims to have evidence that the images actually depict nearby hydrogen gas clouds in our own galaxy, calling into question one of the most important theories in the past 15 years. Verschuur's research will be published December 10 in the Astrophysical Journal.
NASA scientists announced in 1992 that their COBE satellite had imaged the ultimate baby pictures of the universe, revealing the seeds that grew into galaxies like our own Milky Way. And in 2003, higher-resolution images of the seeds were taken by another satellite, the Wilkinson Microwave Anisotropy Probe (WMAP).
According to Verschuur's research, the imaged seeds are located not on the edge of the universe, but nearby. Instead, they're just previously unmapped clouds of "neutral hydrogen" gas located inside the Milky Way. Verschuur sites at least 200 instances where the so-called cosmic seeds lie suspiciously close to known hydrogen clouds inside our galaxy.
Scientists who have reviewed his work suggest Verschuur’s correlations between the WMAP seeds and galactic hydrogen filaments are just coincidences. But as history has shown with previous debates over statistical interpretations, it is likely that Verschuur’s claim will not be settled anytime soon.
To learn more about the Cosmic Background Explorer (COBE) mission, visit the NASA website:
http://lambda.gsfc.nasa.gov/product/cobe/
Wilkinson Microwave Anisotropy Probe (WMAP) mission, visit the NASA website:
http://map.gsfc.nasa.gov/
Hubble Images Do Not Explain Comet 17P/Holmes Outburst
Astronomers are still uncertain what caused the brightening of normally-dim Comet 17P/Holmes, which erupted October 24 and is still shining brightly like a new star in the constellation Perseus.
In a November 15 announcement, three new comet images taken by the Hubble Space Telescope (HST) showed the core of Holmes as a field of particles extending some 15,000 miles across. The images also show that the particles appear to be coming from around the comet's hidden nucleus. This information, combined with another image taken by a ground-based telescope at the Calgary Science Centre (CSC) in Alberta, Canada, supplements the idea of some scientists that something must have broken off from around the nucleus and then disintegrated to become the dust cloud.
According to astronomers, the most likely explanation for the outburst is that a coating of relatively stable water ice, less than 10 miles thick around the comet's nucleus, was suddenly blown away by other, far more volatile chemical ices beneath the frozen water. As those ices heated and expanded violently, they blew the outer ice apart.
The new HST images show no large fragments in the cloud of particles that might suggest they were fragments of the nucleus itself or debris from a collision with a boulder-size asteroid orbiting between Mars and Jupiter - although some astronomers already have proposed that idea.
Seven years ago, HST imaged Comet Holmes, then nearly 150 million miles away. Astronomers inferred from the comet's brightness that its nucleus of rock and ice was barely more than 2 miles wide and that no dust obscured it. But the three new HST images have identified the 15,000-mile core of particles closest to the nucleus.
In addition, the new CSC image shows that at its brightest, the comet's particles extend for at least 2 million miles, with a thinner scattering of particles on its lower right side that may be the beginning of a comet tail.
When British amateur astronomer Edwin Holmes discovered the comet in November of 1892, he detected it because it had suddenly burst into a huge ball of light in his telescope. It then dimmed and, 73 days later, flared up briefly again.
At the time, U.S. astronomer Fred Whipple suggested that the flare-ups occurred because the comet had a double nucleus. Whipple proposed that one nucleus hit the other in a "grazing collision" that triggered the comet's first brilliant cloud of gas and dust, and then a full head-on crash 73 days later created the spectacular second outburst. In recalling Holmes' discovery, some will be watching in mid-January, hoping for a second display.
Still others suggest this year's flare-up might have resulted from a fragile nucleus spinning so fast that it just flew apart.
Astronomers at the Space Telescope Science Institute are studying the feasibility of a 2015 NASA mission to Comet Holmes or some other comet that has a history of flare-ups, and to orbit it long enough to learn the cause and maybe return a sample of the particles.
To learn more, visit Hubble Site, home of NASA's Hubble Space Telescope: http://hubblesite.org/
To learn more about the Calgary Science Centre in Alberta, Canada, visit their website: http://www.calgaryscience.ca/
****************************************
MARS IS COMING, PART 3
As the December 24 opposition approaches, please enjoy this third installment on the Red Planet Mars.
The Atmosphere (Part 1)
In 1947, Dutch-American astronomer Gerard P. Kuiper (1905-1973) determined from telescopic observations that the Martian atmosphere is composed mainly of carbon dioxide. The atmosphere is very thin, pushing at less than 1 percent of Earth's atmospheric pressure at the surface. The altitude varies greatly over the Martian surface, causing surface pressures to range over a factor of 15. Today's atmosphere has only small amounts of water. If it all was extracted and frozen, it would form a layer of ice crystals only 10 micrometers (0.0004 inch) thick, which could be gathered into a solid block of ice not much larger than one of Earth's medium-size icebergs. Geologic evidence suggests that in the distant past the atmosphere was much denser and water was much more abundant at the surface.
The average temperature in the lower atmosphere is about 200 kelvins (K; -100 °F, -70 °C), which is generally colder than the average daytime surface temperature of 250 K (-10 °F, -20 °C). These values are in the same range as those on Earth in Antarctica during winter. In summer above a very dark surface, daytime temperatures at the height of a human can peak at about 290 K (62 °F, 17 °C). Above the turbulent layer close to the surface, temperature decreases with elevation at a rate of about 1.5 K (2.7 °F, 1.5 °C) per km (about 2.4 K [4.3 °F, 2.4 °C] per mile) of altitude.
Unlike that of Earth, the atmosphere of Mars has large seasonal variations in pressure. During each hemisphere’s winter, the main component, carbon dioxide, “snows out” over the winter pole. And during each hemisphere’s spring, the carbon dioxide returns directly to a gas (sublimes). Because the southern winter cap is larger than the northern, atmospheric pressure reaches a minimum during southern winter when the southern cap is at its largest. From Viking lander measurements of the pressure, which was found to vary by 26 percent annually over the mean, scientists calculated that some 7.9 trillion metric tons of carbon dioxide leave and reenter the atmosphere seasonally. This is equivalent to a thickness of at least 23 cm (9 inches) of solid carbon dioxide (dry ice) or several meters of carbon dioxide snow averaged over the vast area of the seasonal polar caps.
Direct chemical analysis at the surface by the Viking landers and spectral observations from orbiting spacecraft allowed scientists to precisely determine the composition of the atmosphere. Where the atmosphere is well mixed by turbulence—below an altitude of 125 km (about 80 miles)—95.3 percent of the atmosphere by weight is carbon dioxide (see the table). This is a comparatively large amount—nine times the quantity now in Earth's much more massive atmosphere. Much of Earth's carbon dioxide, however, is chemically locked in sedimentary rocks; the amount in the Martian atmosphere is less than a thousandth of the terrestrial total. The balance of the Martian atmosphere consists of molecular nitrogen, water vapor, and noble gases (argon, neon, krypton, and xenon). There are also trace amounts of gases that have been produced from the primary constituents by photochemical reactions, generally high in the atmosphere; these include molecular oxygen, carbon monoxide, nitric oxide, and small amounts of ozone.
The lower atmosphere supplies gas to the planet's ionosphere, where densities are low, temperatures are high, and components separate by diffusion according to their masses. Various constituents in the top of the atmosphere are lost to space, which affects the isotopic composition of the remaining gases. For example, because hydrogen is lost preferentially over its heavier isotope deuterium, Mars's atmosphere contains five times more deuterium than Earth's.
Although water is only a minor constituent of the Martian atmosphere (a few molecules per 10,000 at most), primarily because of low atmospheric and surface temperatures, it plays an important role in atmospheric chemistry and meteorology. The Martian atmosphere is effectively saturated with water vapor, yet there is no liquid water present on the surface. The temperature and pressure of the planet are so low that water molecules can exist only as ice or as vapor. Little water is exchanged daily with the surface despite the very cold nighttime surface temperatures.
Most of the information about atmospheric water on Mars has come from the Viking orbiters, which observed seasonal patterns of water content in the atmosphere over a full Martian year. Water vapor is mixed uniformly up to altitudes of 10–15 km (6–9 miles) and shows strong latitudinal gradients that depend on the season. The largest changes occur in the northern hemisphere. During summer in the north, the complete disappearance of the carbon dioxide cap leaves behind a water-ice cap. Sublimation of water from the residual cap results in a strong north-to-south concentration gradient of water vapor in the atmosphere. In the south, where a small carbon dioxide cap remains in summer and only a small amount of water ice has been detected, a strong water vapor gradient does not normally develop in the atmosphere.
The atmospheric water vapor is thought to be in contact with a much larger reservoir in the Martian soil. Subsurface layers of ice are thought to be ubiquitous on Mars at latitudes between 40° and the poles; the very low subsurface temperatures would prevent the ice from subliming. The 2001 Mars Odyssey spacecraft, which began orbital observations of the planet in late 2001, confirmed that ice is present within a meter of the surface at these latitudes, but it is not known how deep the ice layer extends. In contrast, at low latitudes, ice is unstable, and any ice present in the ground would tend to sublime into the atmosphere.
The Viking landers' analytical instruments also measured the isotopic composition of the major and minor atmospheric gases. The similarity of the ratios of isotopes of carbon and oxygen to their terrestrial values implies that large reservoirs of carbon dioxide and water ice exist on Mars and that gases from the reservoirs exchange with those in the atmosphere. The results of other isotopic measurements from Viking suggest that larger amounts of carbon dioxide, nitrogen, and argon were present in the atmosphere in the past and that Mars may have lost much of its inventory of volatile substances early in its history, either to space or to the ground (i.e., locked up chemically in rocks). Some scientists have conjectured that Mars may once have had a much thicker atmosphere but that it was lost to the surface through chemical reactions, which formed carbonates, and to space through large asteroid impacts, which blew off atmospheric gases.
Next Time: “The Atmosphere, Part 2”
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Nov 17, 5:33 PM EST - First Quarter Moon
Nov 17 - Neptune is 1.0° north of Moon, occultation. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Nov 17 - Leonid meteors
Nov 19 - Uranus is 2° south of Moon
Nov 23 - Moon is at perigee, the point in the Moon's orbit when it is closest from Earth.
Nov 24, 9:30 AM EST - Full Moon. Called the “Beaver Moon” or “Snow Moon,” this was the time to set beaver traps before the swamps froze, in order to ensure a supply of winter furs. Others suggest the name refers to the fact that beavers were actively preparing for winter. This full moon is also sometimes called the “Frosty Moon.”
Nov 24 - Uranus is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
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THIS WEEK IN HISTORY
Nov 18, 1989 – Launch of The Cosmic Background Exporer satellite (COBE)
Nov 20, 1889 – Birthday of Edwin Hubble
Nov 20, 2004 - Mars Rover “Spirit” landing on Mars
****************************************
MUSICAL DIVERSION
The Dutch folk song "Wilder dan wilt" (Wilder than wild) has been traced back at least to the late 1500s. The song began "Wilder dan wilt, wie sal mij temmen," or "Wilder than wild, who will tame me?" Here are the verses.
Wilder Dan Wilt
Wilder dan wildt, wie sal my temmen,
plach ick te singhen vroech ende laet;
ick heb geluystert na Christi stemmen,
die heeft my getrocken tot anderen staet.
Ick was soo wilt, 't mocht aen my blijcken,
als eenen voghel vliecht in de locht;
Heer Jesus heeft my met sijn practijcken
soo soetkens al in sijn net ghebrocht.
Vry, liber, en los, en onghebonden,
mijn willeken volchde ick over al;
dat heeft my doen vallen in soo veel sonden,
het welck ick met recht beklaghen sal.
Heer Jesus leert my mijn willeken breken,
al vallet my somtijdts hert en swaer;
daer door kan ick veel quaedts versteken,
in alles gherust volgh' ick hem naer.
Ick plach te gaen proncken lancks de straten,
verciert als een goddinneken ient;
heer Jesus heeft my dit doen verlaten,
mijn kruysken opnemen, dat hy my sent.
Cupido begon my heel te minnen
en te bestralen met sijn venijn;
nu leer ick aen Jesum vast leggen mijn sinnen,
om gracy te vinden voor sijn aenschijn.
Voor 't slempen, en dempen, en triomferen,
oock danssen en springhen met herten bly,
moet'ick nu vasten en abstineren;
mijnen tijdt beschreyen, is mijn party.
O Prince, ick wacht mijn recompence,
als ghy sult oordeelen in den troon;
dat ick dan hooren mach die sentence:
‘komt hier mijn bruydt, ontfanght de kroon.’
-----
Some have suggested this was a bawdy song, but a quick scan of the Dutch lyrics and a rough translation here and there will show several references to "Lord Jesus" and "Christ" and "my sin." Such an observation will tell you this was more of a hymn than a tavern song. The tune may be even older than these words. Whatever the case, it seems apparent that the tune was well known because it was later set to other Dutch lyrics. On January 24, 1597 at the Battle of Turnhout, the Dutch Prince Maurice of Orange defeated Spanish occupiers of a region that is now part of the Netherlands. The Dutch Protestants, who had been forbidden to practice their faith under the Catholic King Philip II of Spain, rejoiced through new hymns that celebrated their victory. On such hymn was written by a poet and writer of songs named Adriaen Valéry, who wrote under Latinized name Adrianus Valerius (1575-1625). He actually wrote this new hymn during the year of the Dutch Protestant victory, but it was not widely published until the year after Valéry's death. We can thank his son François for publishing his collecton, entitled "Nederlandtsche Gedenckclanck." The hymn was entitled “Wilt Heden Nu Treden.”
Wilt Heden Nu Treden
Wilt heden nu treden voor God, den Heere,
Hem boven al loven van harte zeer,
En maken groot zijns lieven namens eere,
Die daar nu onzen vijand slaat terneer.
Ter eeren ons Heeren wilt al uw dagen
Dit wonder bijzonder gedenken toch.
Maakt u, o mensch, voor God steeds wel te dragen,
Doet ieder recht en wacht u voor bedrog!
Bidt, waket en maket, dat g'in bekoring
En 't kwade met schade toch niet en valt.
Uw vroomheid brengt den vijand tot verstoring,
Al waar' zijn rijk nog eens zoo sterk bewald!
-----
In 1877, the German chorus master Eduard Kremser (1838-1914) published a translation of the lyrics from Dutch to Latin along with an arrangement of the tune for chorus and orchestra. From that point, the tune became known to many simply as “Kremser.” A few years later, in 1894, the text was loosely translated to English by U.S.-born musical scholar Theodore Baker (1851-1934). Some of the militant flavor of the original was lost, but essence of the text remained. He called the hymn “We Gather Together.”
We Gather Together
We gather together to ask the Lord’s blessing;
He chastens and hastens His will to make known.
The wicked oppressing now cease from distressing.
Sing praises to His Name; He forgets not His own.
Beside us to guide us, our God with us joining,
Ordaining, maintaining His kingdom divine;
So from the beginning the fight we were winning;
Thou, Lord, were at our side, all glory be Thine!
We all do extol Thee, Thou Leader triumphant,
And pray that Thou still our Defender will be.
Let Thy congregation escape tribulation;
Thy Name be ever praised! O Lord, make us free!
-----
This hymn has become for many an important part of their annual Thanksgiving Day celebrations. And then in 1902, J. Archer Gibson, the organist of the Brick Presbyterian Church in New York City, approached active church member Mrs. Julia B. Cory (1882-1963) with a request for a new setting to the tune. For her inspiration, Cory returned to Valéry’s original hymn text. The new hymn was premiered on the very next Thanksgiving Day, and it was first published in “Hymns of the Living Church” in 1910. Cory called her hymn “We Praise Thee, O God, Our Redeemer, Creator.”
We Praise Thee, O God, Our Redeemer, Creator
We praise Thee, O God, our Redeemer, Creator,
In grateful devotion our tribute we bring;
We lay it before Thee, we kneel and adore Thee,
We bless Thy holy Name, glad praises we sing.
We worship Thee, God of our fathers, we bless Thee;
Through life’s storm and tempest our guide have Thou been;
When perils overtake us, escape Thou will make us,
And with Thy help, O Lord, our battles we win.
With voices united our praises we offer,
To Thee, great Jehovah, glad anthems we raise.
Thy strong arm will guide us, our God is beside us,
To Thee, our great Redeemer, forever be praise.
(Cory later added this Christmas stanza)
Thy love Thou didst show us, Thine only Son sending,
Who came as a Babe and Whose bed was a stall,
His blest life He gave us and then died to save us;
We praise Thee, O Lord, for Thy gift to us all.
-----
To view the lyrics of “Wilder Dan Wilt” visit this link - http://www.dbnl.org/tekst/duys001oude03_01/duys001oude03_01_0169.htm
To see and hear more on the hymn, “Wilt Heden Nu Treden” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/non/nl/wilthede.htm
To see and hear more on the hymn, “We Gather Together” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/e/wegattog.htm
To see and hear more on the hymn, “We Praise Thee, O God, Our Redeemer, Creator” visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/w/p/wptogorc.htm
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Saturday, November 10, 2007
Comet 17P/Holmes Still Amazing Us
Now that a cold front has given central Florida back its nighttime sky, at least for a few evenings, this would be the perfect time to check out amazing Comet 17P/Holmes. In the early morning of October 24, Spanish amateur astronomer Juan Santana noticed that normally dim Comet 17P/Holmes had brightened considerably from observations made on previous nights. The sudden million-fold increase in brightness allowed the comet to become visible to the naked eye. The comet's coma, or outer cloud of gas and dust, is now physically much larger than the planet Jupiter.
It was just such an eruption of gas and dust that allowed the comet to be discovered in November of 1892 by English amateur astronomer Edwin Holmes. This is an excellent imaging target for off-the-shelf digital cameras and backyard telescopes.
The comet is still located just to the East (left) of the constellation Perseus. If you are in the Tampa Bay area, Perseus will rise in the North East and be completely above the horizon after 7PM EST. Comet 17P/Holmes should be visible roughly one-third of the way between Mirfak, the brightest star in Perseus, and the first magnitude wintertime star Capella, the brightest star in the constellation Auriga.
BACKGROUND: Comet 17P/Holmes was discovered by British amateur astronomer Edwin Holmes (1842-1919) on November 6, 1892 while conducting regular observations of the Andromeda Galaxy (M31). The orbital specifics for the comet are as follows: Aphelion distance, 5.2004 AU; Perihelion distance, 2.1655 AU; Semi-major axis, 3.618 AU ; Eccentricity, 0.4120; Orbital period, 7.0679 a (Julian years, lasting 362.25 days); Inclination, 19.1877°; Last perihelion, May 4, 2007; Next perihelion (predicted), March 27, 2014.
For more details and new information, check out these Web pages:
Space Weather Home Page:
http://spaceweather.com/
Space Weather Sky Chart:
http://spaceweather.com/images2007/24oct07/skymap_north_holmes.gif?PHPSESSID=ctmhv5tmpkfnk942ajcl3k17o7
Sky and Telescope Article:
http://www.skyandtelescope.com/observing/home/10862521.html
Phoenix Tilts Its Wings
On November 6, NASA's Phoenix Mars Lander mission team performed a spacecraft orientation adjustment to allow its solar panels to receive more energy from the sun.
During the first three months of the University of Arizona-led mission, which launched August 4, the spacecraft's solar panels were not pointed directly at the sun. If they had, the closer proximity to the sun would have overwhelmed the spacecraft's electrical systems.
With the spacecraft having covered 165 million miles of its 423 million mile journey to Mars, it receives less power as its distance from the sun increases.
The spacecraft also recently did a second trajectory correction maneuver that put it on course to be captured by the Martian gravitation field as it nears the planet. The spacecraft's original course was set from launch so that it would avoid hitting the planet if control problems arose. Additional trajectory corrections are scheduled for April and May to fine-tune the spacecraft's path to its landing site.
The lander is slated to arrive on Mars May 25. The Phoenix mission will look for evidence of water and the elements of life on Mars. It will analyze soil and ice samples scooped from the planet's northern arctic region.
The $420 million mission is led by University of Arizona, the first public institution to lead a mission to Mars. To learn more, visit the mission home page: http://phoenix.lpl.arizona.edu/
Five-Planet Star System Discovered
On November 06, NASA scientists announced the discovery of a record-setting fifth planet discovered orbiting a single star. The discovery suggests that multi-planet systems such as ours may not be unusual.
The star is the sunlike 55 Cancri, located 41 light-years away in the constellation Cancer. Researchers describe the new planet as a "mini-Saturn" of about 46 Earth masses. It is the fourth out from the star in a large gap between the third and fifth planets, placing it in the estimated habitable zone around the star where water might remain liquid.
The planet's size implies that it is a Jovian-like planet of hydrogen and helium gas, but the finding raises the possibility that earthlike moons might be orbiting the planet.
55 Cancri's system of five planets all seem to orbit along relatively circular paths, and the farthest planet out, a gaseous super-giant the size of four Jupiters, orbits at roughly the same distance from its star as the the distance of our Jupiter from the sun.
55 Cancri's innermost planet, weighing in at more than 10 earth masses—meaning it could have a rocky or icy core—lies closer to its star than Mercury does to our own. The new planet sits at 0.8 earth-sun distances (astronomical units) from the star, or roughly the distance between Venus and the sun. Before this discovery, researchers knew of only one other four-planet system, Mu Arae, and several three-planet systems.
55 Cancri system is one of many stars that for 18 years have been carefully and regularly measured by California's Lick Observatory and Hawaii's Keck Telescope. Researchers looked at the star's Doppler shift--the change in the wavelength, or color, of its light as it moved toward and away from Earth. A star tugged by an orbiting planet will wobble slightly, which can be detected as a regular shift in the star's color corresponding to the time the planet requires to complete an orbit. For example, 55 Cancri's outer planet has an orbital period of 14 years, and so was not discovered until 2004.
The research team's report has been accepted for future publication in The Astrophysical Journal. To learn more about the discovery and the observatories participating in the research, check these links:
University of California Observatories, Lick Observatory:
http://www.ucolick.org/
W. M. Keck Observatory:
http://www.keckobservatory.org/
Leonid Meteors Return
November 17 marks the peak of the annual Leonid meteor shower. Meteors from this shower may be visible from Nov. 15 through Nov. 20. Leonid meteors have an entry velocity of 71 km/second and glow with a bluish-green tint. This shower is caused by Periodic Comet 55P/Tempel-Tuttle, which returns to the inner solar system every 32.9 years. Meteor hourly rates are irregular and may reach 40 or greater in years surrounding the return of the comet. But since that last occurred in 1999, we can probably expect a rate of 10 to 15 per hour. The best chances to see Leonids are in the early morning hours during the days surrounding the peak (Nov. 16, 17, 18). The meteors will appear to originate from a point in the constellation of Leo (RA 10hrs 08min, Dec +22°).
The Leonids played a great role in our understanding of meteor showers. The great meteor storm of November 12-13, 1833 is regarded as the date of the birth of meteor astronomy. Following that meteor storm, Professors Olmsted and Twining of then Yale College pointed out that the meteors appeared to radiate from a point in the constellation Leo, the Lion. The fact that the meteors radiated from a single point indicated that they were all part of a swarm of meteoroids moving in the same orbital path. Later, Professor Hubert Anson Newton (1830-1896) an astronomer and mathematician who was also of Yale College, calculated that the orbit had a period of 33 years and used records to trace appearances of the shower as far back as AD 902. He also observed that the time of the Leonid shower moved along the calendar at the rate of about a month in a hundred years. Newton then successfully predicted the appearance of the 1866 Leonid storm. A few weeks after the 1866 storm astronomers found that the orbit of the meteoroid stream was identical with Temple's Comet, seen a year earlier. About this same time Italian astronomer Giovanni Schiaparelli (1835-1910) showed that the Perseid meteors came from a stream that moved in an orbit identical to the bright comet of 1862. These were the first observations to connect comets with the fall meteor showers.
There is historical evidence that Abraham Lincoln (1809-1865) also witnessed the great Leonid meteor storm of 1833 as a young man of 24. According to cross-referenced records and personal journals, Lincoln was apparently in New Salem, Illinois staying at the Rutledge Tavern, a log cabin then owned by Henry Onstot, a cooper by trade (bucket and barrel maker) and member of the Cumberland Presbyterian Church. Lincoln recounted the story in the presence of American writer Walt Whitman (1819-1892) who was a frequent guest of the Lincoln White House. Whitman later published the story in his book "Specimen Days & Collect," published in 1882. When asked by another White House guest whether the Union would survive the ongoing Civil War, Whitman noted that Lincoln, ever the story-teller, replied with this story. "When I was a young man in Illinois," said he, "I boarded for a time with a Deacon of the Presbyterian church. One night I was roused from my sleep by a rap at the door, & I heard the Deacon's voice exclaiming 'Arise, Abraham, the day of judgement has come!' I sprang from my bed & rushed to the window, and saw the stars falling in great showers! But looking back of them in the heavens I saw all the grand old constellations with which I was so well acquainted, fixed and true in their places. Gentlemen, the world did not come to an end then, nor will the Union now."
Thank Yous
Thanks to MARS member James Dagget who, following our report on quasars in early galaxies, shared his memories of working in the Quasar TV plant in Plantation, Florida the 1970s. James knows better than most about the inconsistent "quality" that went into those sets before the name went on.
Thanks to MARS member Craig MacDougal for sharing his backyard binocular observation of Comet 17P/Holmes during an all-too-brief break in the cloud cover last week. At that time the comet shone brighter than second magnitude and still continues to impress us now.
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MARS IS COMING, PART 2
As we prepare for the December 24 opposition, please enjoy this next installment on the Red Planet Mars.
Early Observations
Mars was a puzzle to ancient astronomers. They did not understand why it sometimes moved through the sky in the same direction as the sun and other celestial objects (direct, or prograde, motion), and sometimes moved in the opposite direction (retrograde motion). In 1609 the German mathematician and astronomer Johannes Kepler (1571-1630) used the excellent naked-eye observations of Danish astronomer Tycho Brahe (1546-1601) to deduce empirically the laws of motion for Mars and so pave the way for the modern gravitational theory of the solar system. Rather than having a circular orbit with uniform motion, as suggested by earlier Ptolemy-inspired theories, Kepler found that the orbit of Mars was an ellipse along which the planet moved with non-uniform but predictable motion--faster when closer to the sun, slower when farther away.
The earliest telescopic observations of Mars were made in 1610 by Italian astronomer Galileo Galilei (1564-1642) . This was also the first time that Mars was clearly seen not as a point of light, but as a disk. The Dutch scientist and mathematician Christiaan Huygens (1629-1695) is credited with the first accurate drawings of the planet's surface markings. In 1659 Huygens made a drawing that showed a major dark marking that is now known as Syrtis Major. About 1666, the Martian polar caps were first noted by the Italian-born French astronomer Gian Domenico Cassini (1625-1712).
Many key discoveries were made by visual observers. In 1659, Huygens discovered that Mars rotates and, in 1666, measured that rotation to be 24 hours 40 minutes--over today’s measurement by only 3 minutes. In the 1780s, German-born British astronomer William Herschel (1738-1822) first noted the very thin Martian atmosphere, and Herschel also measured the tilt of the planet's rotation axis and first discussed the Martian seasons. In 1877 the U.S. Naval Observatory's Asaph Hall (1829-1907) discovered that Mars has two natural satellites. Visual observers also documented many meteorological and seasonal changes that occur on Mars, such as various cloud types, the growing and shrinking of the polar caps, changes in the color and size of the dark areas, an annual "wave of darkening" in the markings that sweeps across the planet in time with the shrinking of the polar caps, and an occasional "blue haze" in the atmosphere. Most of these events were not explained until Mars was visited by spacecraft.
Visible Surface Features
Aside from the white polar caps, Earth-based telescopes show Mars generally to have a bright red-orange-colored surface that is covered by dark markings. Originally, the bright areas were called deserts, and most of the large dark areas were called maria (Latin, meaning "oceans" or "seas") because observers once thought the dark areas were covered by water.
The dark markings cover about one-third of the surface, mostly in a band around the planet between latitudes 10° and 40° South. They are irregularly distributed, and their overall pattern can change over many years. The northern hemisphere has only three major dark features. One is called Acidalia Planitia, another is called Syrtis Major, and the third is a dark collar around the northern pole. These were once thought to be shallow seas or areas of vegetation. We now know that Mars' dark areas form and change as the winds move surface material. Images from orbiting spacecraft reveal that the dark areas are actually collections of many dark streaks and splotches that are associated with craters, ridges, hills, and other geologic features that can block the local winds.
The bright areas, which cover about two-thirds of the surface, have subtle shadings, but these probably also are the result of the winds moving surface material. Beginning in 1877 with Italian astronomer Giovanni Schiaparelli (1835-1910) and into the early 20th century, maps of Mars showed many canals or channels—thin lines connecting the darker surface markings and thought by some at the time to be transportation for agricultural irrigation. However, these markings were not seen later in the images taken by flyby and orbiting spacecraft. The canals were apparently features that observers thought they saw while trying to push the resolution limits of their telescopes. Other features, such as the "wave of darkening" and the "blue haze" described by early telescopic observers, are now known to result from a combination of the viewing conditions and changes in the reflective properties of the surface.
For telescopic observers, the most dramatic regular changes on Mars occur at the poles. As fall begins in a particular hemisphere, clouds develop over that polar region, and the cap, made of frozen carbon dioxide, begins to grow. The smaller cap in the north can extend to 55° latitude, the larger cap in the south can extend to 50° latitude. In spring the caps recede. During northern summer the northern carbon dioxide cap disappears completely, leaving behind a small water-ice cap. And during the southern summer there is a small residual cap composed of carbon dioxide ice and water ice.
Early telescopic observers noted times when Martian surface features were temporarily hidden. They generally thought these were caused by white clouds or yellow clouds, and they interpreted the white clouds to be gas and the yellow clouds to be dust. Spacecraft images have since confirmed these interpretations were correct, and that hazes, clouds, and fogs regularly hide the surface.
Images from spacecraft in Mars orbit have found a variety of low-lying clouds and fogs, often in topographic depressions such as valleys or craters. They have also revealed high, thin clouds, particularly at the terminator--the dividing line between the daytime and nighttime portions of the planet's observable disk. Orographic clouds, which are produced when moist air is lifted over elevated terrain and cooled, form around prominent topographic features such as craters and volcanoes. Winter at the middle latitudes is characterized by westward-moving, spiral-shaped storm systems that are similar to those on Earth. Most of these clouds are composed of water ice--the white clouds that were seen by the early telescopic observers.
Dust storms are common on Mars. They can occur at any time but are most frequent in southern spring and summer, when Mars is passing closest to the sun and surface temperatures are at their highest. Most of the storms are regional in extent and last a few weeks. But every two or three years, the dust storms become global. At their peak, dust is carried so high in the atmosphere that only the summits of the tallest volcanoes--up to 21 km (13 miles) above the planet's mean radius--are visible. Although too small to be observed from Earth, the small sand tornados, called dust devils, have been seen by spacecraft in Mars orbit and by surface craft such as Mars Pathfinder and the Mars Exploration Rovers.
Next time: "The Martian Atmosphere"
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Nov 11 - Dwarf Planet Ceres is at opposition (7.2 Magnitude)
Nov 11 – the star Antares is 0.4° north of the moon, occultation. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Nov 12 – Jupiter is 5° north of the moon
Nov 12 - Dwarf Planet Ceres at its closest approach to Earth (1.832 AU)
Nov 14 – Asteroid Juno is in conjunction with the sun
Nov 15 - Mars is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
Nov 17, 5:33 P.M. EST - First Quarter Moon
Nov 17 - Neptune is 1.0° north of the moon, occultation. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Nov 17 – the moon occults the planet Neptune
Nov 17 - Leonid Meteor Shower Peak
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THIS WEEK IN HISTORY
Nov 11, 1572 - Tycho Brahe's Discovery of a supernova, SN1572, 435th anniversary
Nov 11, 1875 - Vesto Slipher's birthday
Nov 11, 1966 - Gemini 12 launch (Jim Lovell and Buzz Aldrin)
Nov 12, 1891 - Seth Nicholson's birthday
Nov 12, 1924 - Audouin Dollfus' birthday
Nov 12, 1980 - Voyager 1, Saturn Flyby
Nov 13, 1831 - James Clerk Maxwell's birthday
Nov 14, 1969 - Apollo 12 Launch (Manned Moon Mission)
Nov 14, 1971 - Mariner 9, Mars Orbit Insertion
Nov 16, 2001 - Genesis, L1 Orbit Insertion
Nov 17, 1597 - Henry Gellibrand's 410th Birthday
Nov 17, 1966 – Leonid Meteor Storm
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MUSICAL DIVERSION
The song called "The Girl I Left Behind Me" has much folklore associated with it. Some say the song’s tune was popular as far back as the reign of Queen Elizabeth I, and that it was regularly played when regiments left town or when man-of-war ships set sail.
One source reports that the tune was known in America as early as 1650 and that it was a traditional fife tune, imported from England as "Brighten Camp." The tune became generally popular during the American Revolution. The tune was known in Ireland as "The Rambling Laborer" and "The Spailpin Fanach" and was first published in Dublin in 1791.
The tune is easy to play on the fife--a small flute. This song, along with “Yankee Doodle,” is often associated with the famous painting called “The Spirit of ’76.”
There are many settings for this tune. Below are two version of “The Girl I Left Behind Me.” The first comes from a collection called “Songs of the Seventh Calvary.” The origin of the other version is not certain. A third song based on this tune follows them.
The Girl I Left Behind Me
(from “Songs of the Seventh Calvary”)
The hours sad I left a maid
A lingering farewell taking
Whose sighs and tears my steps delayed
I thought her heart was breaking
In hurried words her name I blest
I breathed the vows that bind me
And to my heart in anguish pressed
The girl I left behind me
Then to the east we bore away
To win a name in story
And there where dawns the sun of day
There dawned our sun of glory
The place in my sight
When in the host assigned me
I shared the glory of that fight
Sweet girl I left behind me
Though many a name our banner bore
Of former deeds of daring
But they were of the day of yore
In which we had no sharing
But now our laurels freshly won
With the old one shall entwine me
Singing worthy of our size each son
Sweet girl I left behind me
The hope of final victory
Within my bosom burning
Is mingling with sweet thoughts of thee
And of my fond returning
But should I n'eer return again
Still with thy love i'll bind me
Dishonors breath shall never stain
The name I leave behind me
-----
The Girl I Left Behind Me
(an alternate version)
I'm lonesome since I crossed the hill,
And o'er the moorland sedgy
Such heavy thoughts my heart do fill,
Since parting with my Betsey
I seek for one as fair and gay,
But find none to remind me
How sweet the hours I passed away,
With the girl I left behind me.
O ne'er shall I foget the night,
the stars were bright above me
And gently lent their silv'ry light
when first she vowed to love me
But now I'm bound to Brighton camp
kind heaven then pray guide me
And send me safely back again,
to the girl I left behind me
Her golden hair in ringlets fair,
her eyes like diamonds shining
Her slender waist, her heavenly face,
that leaves my heart still pining
Ye gods above oh hear my prayer
to my beauteous fair to find me
And send me safely back again,
to the girl I left behind me
The bee shall honey taste no more,
the dove become a ranger
The falling waters cease to roar,
ere I shall seek to change her
The vows we made to heav'n above
shall ever cheer and bind me
In constancy to her I love,
the girl I left behind me.
-----
"Waxie's Dargle" is an old drinking song that is set to the same tune. Waxies were candlemakers, traditionally women, and "dargle" was a term for their annual working trip to Bray in Ireland. The River Dargle begins up in the Wicklow Mountains and finally empties into Irish Sea in Bray Harbor. Another source says the Dargle (a popular pub) was also a holiday haunt of the late eighteenth century Dublin candlemaker and grocer, Waxy O'Connor.
Here are some translations for the lyrics. “Auld one,” or old one, means wife. “Auld lad,” or old lad, means husband. In some versions the word “Uncle” is substituted with the phrase "Young Kill."
Waxie's Dargle
Says my auld one to your auld one
Will you come to the Waxie's dargle
Says your auld one to my auld one
Sure I haven't got a farthing
I've just been down to Monto town
To see Uncle McArdle
But he wouldn't lend me a half a crown
To go to the Waxie's dargle
Chorus:
What'll you have, will you have a pint
Yes, I'll have a pint with you, sir
And if one of us doesn't order soon
We'll be thrown out of the boozer
Says my auld one to your auld one
Will you come to the Galway races
Says your auld one to my auld one
With the price of my auld lad's braces
I went down to Capel Street
To the pawn shop money lenders
But they wouldn't give me a couple of bob
On my auld lad's red suspenders
(chorus)
Says my auld one to your auld one
We've got no beef nor mutton
But if we go down to Monto town
We might get a drink for nothin'
Here's a piece of good advice
I got from an auld fish-monger
When food is scarce and you see the hearse
You'll know you've died of hunger
(chorus)
-----
To review some the history, the text, or to listen to the melody, check out this pages from the "Songs of England" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts"
- (The Girl I left Behind Me, Version 1) http://www.contemplator.com/england/girl.html
- (The Girl I left Behind Me, Version 2) http://www.contemplator.com/england/girl2.html
- (Waxie's Dargle) http://www.contemplator.com/england/waxie.html
To see a GIF image file of the score of the song, or to download an ABC file of the score, or other notations, visit this mirror site of Digital Tradition - http://sniff.numachi.com/pages/tiGIRLLFT1;ttBRGHTON.html
To see a GIF image file of the score of the song, or to download an ABC file of the score, visit this page of "The Session" - http://www.thesession.org/tunes/display/5418
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Now that a cold front has given central Florida back its nighttime sky, at least for a few evenings, this would be the perfect time to check out amazing Comet 17P/Holmes. In the early morning of October 24, Spanish amateur astronomer Juan Santana noticed that normally dim Comet 17P/Holmes had brightened considerably from observations made on previous nights. The sudden million-fold increase in brightness allowed the comet to become visible to the naked eye. The comet's coma, or outer cloud of gas and dust, is now physically much larger than the planet Jupiter.
It was just such an eruption of gas and dust that allowed the comet to be discovered in November of 1892 by English amateur astronomer Edwin Holmes. This is an excellent imaging target for off-the-shelf digital cameras and backyard telescopes.
The comet is still located just to the East (left) of the constellation Perseus. If you are in the Tampa Bay area, Perseus will rise in the North East and be completely above the horizon after 7PM EST. Comet 17P/Holmes should be visible roughly one-third of the way between Mirfak, the brightest star in Perseus, and the first magnitude wintertime star Capella, the brightest star in the constellation Auriga.
BACKGROUND: Comet 17P/Holmes was discovered by British amateur astronomer Edwin Holmes (1842-1919) on November 6, 1892 while conducting regular observations of the Andromeda Galaxy (M31). The orbital specifics for the comet are as follows: Aphelion distance, 5.2004 AU; Perihelion distance, 2.1655 AU; Semi-major axis, 3.618 AU ; Eccentricity, 0.4120; Orbital period, 7.0679 a (Julian years, lasting 362.25 days); Inclination, 19.1877°; Last perihelion, May 4, 2007; Next perihelion (predicted), March 27, 2014.
For more details and new information, check out these Web pages:
Space Weather Home Page:
http://spaceweather.com/
Space Weather Sky Chart:
http://spaceweather.com/images2007/24oct07/skymap_north_holmes.gif?PHPSESSID=ctmhv5tmpkfnk942ajcl3k17o7
Sky and Telescope Article:
http://www.skyandtelescope.com/observing/home/10862521.html
Phoenix Tilts Its Wings
On November 6, NASA's Phoenix Mars Lander mission team performed a spacecraft orientation adjustment to allow its solar panels to receive more energy from the sun.
During the first three months of the University of Arizona-led mission, which launched August 4, the spacecraft's solar panels were not pointed directly at the sun. If they had, the closer proximity to the sun would have overwhelmed the spacecraft's electrical systems.
With the spacecraft having covered 165 million miles of its 423 million mile journey to Mars, it receives less power as its distance from the sun increases.
The spacecraft also recently did a second trajectory correction maneuver that put it on course to be captured by the Martian gravitation field as it nears the planet. The spacecraft's original course was set from launch so that it would avoid hitting the planet if control problems arose. Additional trajectory corrections are scheduled for April and May to fine-tune the spacecraft's path to its landing site.
The lander is slated to arrive on Mars May 25. The Phoenix mission will look for evidence of water and the elements of life on Mars. It will analyze soil and ice samples scooped from the planet's northern arctic region.
The $420 million mission is led by University of Arizona, the first public institution to lead a mission to Mars. To learn more, visit the mission home page: http://phoenix.lpl.arizona.edu/
Five-Planet Star System Discovered
On November 06, NASA scientists announced the discovery of a record-setting fifth planet discovered orbiting a single star. The discovery suggests that multi-planet systems such as ours may not be unusual.
The star is the sunlike 55 Cancri, located 41 light-years away in the constellation Cancer. Researchers describe the new planet as a "mini-Saturn" of about 46 Earth masses. It is the fourth out from the star in a large gap between the third and fifth planets, placing it in the estimated habitable zone around the star where water might remain liquid.
The planet's size implies that it is a Jovian-like planet of hydrogen and helium gas, but the finding raises the possibility that earthlike moons might be orbiting the planet.
55 Cancri's system of five planets all seem to orbit along relatively circular paths, and the farthest planet out, a gaseous super-giant the size of four Jupiters, orbits at roughly the same distance from its star as the the distance of our Jupiter from the sun.
55 Cancri's innermost planet, weighing in at more than 10 earth masses—meaning it could have a rocky or icy core—lies closer to its star than Mercury does to our own. The new planet sits at 0.8 earth-sun distances (astronomical units) from the star, or roughly the distance between Venus and the sun. Before this discovery, researchers knew of only one other four-planet system, Mu Arae, and several three-planet systems.
55 Cancri system is one of many stars that for 18 years have been carefully and regularly measured by California's Lick Observatory and Hawaii's Keck Telescope. Researchers looked at the star's Doppler shift--the change in the wavelength, or color, of its light as it moved toward and away from Earth. A star tugged by an orbiting planet will wobble slightly, which can be detected as a regular shift in the star's color corresponding to the time the planet requires to complete an orbit. For example, 55 Cancri's outer planet has an orbital period of 14 years, and so was not discovered until 2004.
The research team's report has been accepted for future publication in The Astrophysical Journal. To learn more about the discovery and the observatories participating in the research, check these links:
University of California Observatories, Lick Observatory:
http://www.ucolick.org/
W. M. Keck Observatory:
http://www.keckobservatory.org/
Leonid Meteors Return
November 17 marks the peak of the annual Leonid meteor shower. Meteors from this shower may be visible from Nov. 15 through Nov. 20. Leonid meteors have an entry velocity of 71 km/second and glow with a bluish-green tint. This shower is caused by Periodic Comet 55P/Tempel-Tuttle, which returns to the inner solar system every 32.9 years. Meteor hourly rates are irregular and may reach 40 or greater in years surrounding the return of the comet. But since that last occurred in 1999, we can probably expect a rate of 10 to 15 per hour. The best chances to see Leonids are in the early morning hours during the days surrounding the peak (Nov. 16, 17, 18). The meteors will appear to originate from a point in the constellation of Leo (RA 10hrs 08min, Dec +22°).
The Leonids played a great role in our understanding of meteor showers. The great meteor storm of November 12-13, 1833 is regarded as the date of the birth of meteor astronomy. Following that meteor storm, Professors Olmsted and Twining of then Yale College pointed out that the meteors appeared to radiate from a point in the constellation Leo, the Lion. The fact that the meteors radiated from a single point indicated that they were all part of a swarm of meteoroids moving in the same orbital path. Later, Professor Hubert Anson Newton (1830-1896) an astronomer and mathematician who was also of Yale College, calculated that the orbit had a period of 33 years and used records to trace appearances of the shower as far back as AD 902. He also observed that the time of the Leonid shower moved along the calendar at the rate of about a month in a hundred years. Newton then successfully predicted the appearance of the 1866 Leonid storm. A few weeks after the 1866 storm astronomers found that the orbit of the meteoroid stream was identical with Temple's Comet, seen a year earlier. About this same time Italian astronomer Giovanni Schiaparelli (1835-1910) showed that the Perseid meteors came from a stream that moved in an orbit identical to the bright comet of 1862. These were the first observations to connect comets with the fall meteor showers.
There is historical evidence that Abraham Lincoln (1809-1865) also witnessed the great Leonid meteor storm of 1833 as a young man of 24. According to cross-referenced records and personal journals, Lincoln was apparently in New Salem, Illinois staying at the Rutledge Tavern, a log cabin then owned by Henry Onstot, a cooper by trade (bucket and barrel maker) and member of the Cumberland Presbyterian Church. Lincoln recounted the story in the presence of American writer Walt Whitman (1819-1892) who was a frequent guest of the Lincoln White House. Whitman later published the story in his book "Specimen Days & Collect," published in 1882. When asked by another White House guest whether the Union would survive the ongoing Civil War, Whitman noted that Lincoln, ever the story-teller, replied with this story. "When I was a young man in Illinois," said he, "I boarded for a time with a Deacon of the Presbyterian church. One night I was roused from my sleep by a rap at the door, & I heard the Deacon's voice exclaiming 'Arise, Abraham, the day of judgement has come!' I sprang from my bed & rushed to the window, and saw the stars falling in great showers! But looking back of them in the heavens I saw all the grand old constellations with which I was so well acquainted, fixed and true in their places. Gentlemen, the world did not come to an end then, nor will the Union now."
Thank Yous
Thanks to MARS member James Dagget who, following our report on quasars in early galaxies, shared his memories of working in the Quasar TV plant in Plantation, Florida the 1970s. James knows better than most about the inconsistent "quality" that went into those sets before the name went on.
Thanks to MARS member Craig MacDougal for sharing his backyard binocular observation of Comet 17P/Holmes during an all-too-brief break in the cloud cover last week. At that time the comet shone brighter than second magnitude and still continues to impress us now.
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MARS IS COMING, PART 2
As we prepare for the December 24 opposition, please enjoy this next installment on the Red Planet Mars.
Early Observations
Mars was a puzzle to ancient astronomers. They did not understand why it sometimes moved through the sky in the same direction as the sun and other celestial objects (direct, or prograde, motion), and sometimes moved in the opposite direction (retrograde motion). In 1609 the German mathematician and astronomer Johannes Kepler (1571-1630) used the excellent naked-eye observations of Danish astronomer Tycho Brahe (1546-1601) to deduce empirically the laws of motion for Mars and so pave the way for the modern gravitational theory of the solar system. Rather than having a circular orbit with uniform motion, as suggested by earlier Ptolemy-inspired theories, Kepler found that the orbit of Mars was an ellipse along which the planet moved with non-uniform but predictable motion--faster when closer to the sun, slower when farther away.
The earliest telescopic observations of Mars were made in 1610 by Italian astronomer Galileo Galilei (1564-1642) . This was also the first time that Mars was clearly seen not as a point of light, but as a disk. The Dutch scientist and mathematician Christiaan Huygens (1629-1695) is credited with the first accurate drawings of the planet's surface markings. In 1659 Huygens made a drawing that showed a major dark marking that is now known as Syrtis Major. About 1666, the Martian polar caps were first noted by the Italian-born French astronomer Gian Domenico Cassini (1625-1712).
Many key discoveries were made by visual observers. In 1659, Huygens discovered that Mars rotates and, in 1666, measured that rotation to be 24 hours 40 minutes--over today’s measurement by only 3 minutes. In the 1780s, German-born British astronomer William Herschel (1738-1822) first noted the very thin Martian atmosphere, and Herschel also measured the tilt of the planet's rotation axis and first discussed the Martian seasons. In 1877 the U.S. Naval Observatory's Asaph Hall (1829-1907) discovered that Mars has two natural satellites. Visual observers also documented many meteorological and seasonal changes that occur on Mars, such as various cloud types, the growing and shrinking of the polar caps, changes in the color and size of the dark areas, an annual "wave of darkening" in the markings that sweeps across the planet in time with the shrinking of the polar caps, and an occasional "blue haze" in the atmosphere. Most of these events were not explained until Mars was visited by spacecraft.
Visible Surface Features
Aside from the white polar caps, Earth-based telescopes show Mars generally to have a bright red-orange-colored surface that is covered by dark markings. Originally, the bright areas were called deserts, and most of the large dark areas were called maria (Latin, meaning "oceans" or "seas") because observers once thought the dark areas were covered by water.
The dark markings cover about one-third of the surface, mostly in a band around the planet between latitudes 10° and 40° South. They are irregularly distributed, and their overall pattern can change over many years. The northern hemisphere has only three major dark features. One is called Acidalia Planitia, another is called Syrtis Major, and the third is a dark collar around the northern pole. These were once thought to be shallow seas or areas of vegetation. We now know that Mars' dark areas form and change as the winds move surface material. Images from orbiting spacecraft reveal that the dark areas are actually collections of many dark streaks and splotches that are associated with craters, ridges, hills, and other geologic features that can block the local winds.
The bright areas, which cover about two-thirds of the surface, have subtle shadings, but these probably also are the result of the winds moving surface material. Beginning in 1877 with Italian astronomer Giovanni Schiaparelli (1835-1910) and into the early 20th century, maps of Mars showed many canals or channels—thin lines connecting the darker surface markings and thought by some at the time to be transportation for agricultural irrigation. However, these markings were not seen later in the images taken by flyby and orbiting spacecraft. The canals were apparently features that observers thought they saw while trying to push the resolution limits of their telescopes. Other features, such as the "wave of darkening" and the "blue haze" described by early telescopic observers, are now known to result from a combination of the viewing conditions and changes in the reflective properties of the surface.
For telescopic observers, the most dramatic regular changes on Mars occur at the poles. As fall begins in a particular hemisphere, clouds develop over that polar region, and the cap, made of frozen carbon dioxide, begins to grow. The smaller cap in the north can extend to 55° latitude, the larger cap in the south can extend to 50° latitude. In spring the caps recede. During northern summer the northern carbon dioxide cap disappears completely, leaving behind a small water-ice cap. And during the southern summer there is a small residual cap composed of carbon dioxide ice and water ice.
Early telescopic observers noted times when Martian surface features were temporarily hidden. They generally thought these were caused by white clouds or yellow clouds, and they interpreted the white clouds to be gas and the yellow clouds to be dust. Spacecraft images have since confirmed these interpretations were correct, and that hazes, clouds, and fogs regularly hide the surface.
Images from spacecraft in Mars orbit have found a variety of low-lying clouds and fogs, often in topographic depressions such as valleys or craters. They have also revealed high, thin clouds, particularly at the terminator--the dividing line between the daytime and nighttime portions of the planet's observable disk. Orographic clouds, which are produced when moist air is lifted over elevated terrain and cooled, form around prominent topographic features such as craters and volcanoes. Winter at the middle latitudes is characterized by westward-moving, spiral-shaped storm systems that are similar to those on Earth. Most of these clouds are composed of water ice--the white clouds that were seen by the early telescopic observers.
Dust storms are common on Mars. They can occur at any time but are most frequent in southern spring and summer, when Mars is passing closest to the sun and surface temperatures are at their highest. Most of the storms are regional in extent and last a few weeks. But every two or three years, the dust storms become global. At their peak, dust is carried so high in the atmosphere that only the summits of the tallest volcanoes--up to 21 km (13 miles) above the planet's mean radius--are visible. Although too small to be observed from Earth, the small sand tornados, called dust devils, have been seen by spacecraft in Mars orbit and by surface craft such as Mars Pathfinder and the Mars Exploration Rovers.
Next time: "The Martian Atmosphere"
Bibliography
Mars. (2007). In Encyclopædia Britannica. Retrieved October 26, 2007 , from Encyclopædia Britannica Online: http://www.britannica.com/eb/article-9110149
Mars (2007). In The Columbia Encyclopedia, Sixth Edition 2007. Copyright 2007 Columbia University Press. Retrieved October 26, 2007 from Encyclopedia.com
http://www.encyclopedia.com/doc/1E1-Mars-ast.html
Planets: Mars. In NASA Solar System Exploration, Last updated October 23, 2007. Retrieved October 26, 2007, from the NASA Solar System Exploration website, maintained by NASA's Jet Propulsion Laboratory:
http://solarsystem.jpl.nasa.gov/planets/profile.cfm?Object=Mars
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THE SKY THIS WEEK
Nov 11 - Dwarf Planet Ceres is at opposition (7.2 Magnitude)
Nov 11 – the star Antares is 0.4° north of the moon, occultation. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Nov 12 – Jupiter is 5° north of the moon
Nov 12 - Dwarf Planet Ceres at its closest approach to Earth (1.832 AU)
Nov 14 – Asteroid Juno is in conjunction with the sun
Nov 15 - Mars is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.
Nov 17, 5:33 P.M. EST - First Quarter Moon
Nov 17 - Neptune is 1.0° north of the moon, occultation. An occultation occurs when one object passes in front of a smaller one, temporarily obscuring all or part of the background object from view.
Nov 17 – the moon occults the planet Neptune
Nov 17 - Leonid Meteor Shower Peak
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THIS WEEK IN HISTORY
Nov 11, 1572 - Tycho Brahe's Discovery of a supernova, SN1572, 435th anniversary
Nov 11, 1875 - Vesto Slipher's birthday
Nov 11, 1966 - Gemini 12 launch (Jim Lovell and Buzz Aldrin)
Nov 12, 1891 - Seth Nicholson's birthday
Nov 12, 1924 - Audouin Dollfus' birthday
Nov 12, 1980 - Voyager 1, Saturn Flyby
Nov 13, 1831 - James Clerk Maxwell's birthday
Nov 14, 1969 - Apollo 12 Launch (Manned Moon Mission)
Nov 14, 1971 - Mariner 9, Mars Orbit Insertion
Nov 16, 2001 - Genesis, L1 Orbit Insertion
Nov 17, 1597 - Henry Gellibrand's 410th Birthday
Nov 17, 1966 – Leonid Meteor Storm
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MUSICAL DIVERSION
The song called "The Girl I Left Behind Me" has much folklore associated with it. Some say the song’s tune was popular as far back as the reign of Queen Elizabeth I, and that it was regularly played when regiments left town or when man-of-war ships set sail.
One source reports that the tune was known in America as early as 1650 and that it was a traditional fife tune, imported from England as "Brighten Camp." The tune became generally popular during the American Revolution. The tune was known in Ireland as "The Rambling Laborer" and "The Spailpin Fanach" and was first published in Dublin in 1791.
The tune is easy to play on the fife--a small flute. This song, along with “Yankee Doodle,” is often associated with the famous painting called “The Spirit of ’76.”
There are many settings for this tune. Below are two version of “The Girl I Left Behind Me.” The first comes from a collection called “Songs of the Seventh Calvary.” The origin of the other version is not certain. A third song based on this tune follows them.
The Girl I Left Behind Me
(from “Songs of the Seventh Calvary”)
The hours sad I left a maid
A lingering farewell taking
Whose sighs and tears my steps delayed
I thought her heart was breaking
In hurried words her name I blest
I breathed the vows that bind me
And to my heart in anguish pressed
The girl I left behind me
Then to the east we bore away
To win a name in story
And there where dawns the sun of day
There dawned our sun of glory
The place in my sight
When in the host assigned me
I shared the glory of that fight
Sweet girl I left behind me
Though many a name our banner bore
Of former deeds of daring
But they were of the day of yore
In which we had no sharing
But now our laurels freshly won
With the old one shall entwine me
Singing worthy of our size each son
Sweet girl I left behind me
The hope of final victory
Within my bosom burning
Is mingling with sweet thoughts of thee
And of my fond returning
But should I n'eer return again
Still with thy love i'll bind me
Dishonors breath shall never stain
The name I leave behind me
-----
The Girl I Left Behind Me
(an alternate version)
I'm lonesome since I crossed the hill,
And o'er the moorland sedgy
Such heavy thoughts my heart do fill,
Since parting with my Betsey
I seek for one as fair and gay,
But find none to remind me
How sweet the hours I passed away,
With the girl I left behind me.
O ne'er shall I foget the night,
the stars were bright above me
And gently lent their silv'ry light
when first she vowed to love me
But now I'm bound to Brighton camp
kind heaven then pray guide me
And send me safely back again,
to the girl I left behind me
Her golden hair in ringlets fair,
her eyes like diamonds shining
Her slender waist, her heavenly face,
that leaves my heart still pining
Ye gods above oh hear my prayer
to my beauteous fair to find me
And send me safely back again,
to the girl I left behind me
The bee shall honey taste no more,
the dove become a ranger
The falling waters cease to roar,
ere I shall seek to change her
The vows we made to heav'n above
shall ever cheer and bind me
In constancy to her I love,
the girl I left behind me.
-----
"Waxie's Dargle" is an old drinking song that is set to the same tune. Waxies were candlemakers, traditionally women, and "dargle" was a term for their annual working trip to Bray in Ireland. The River Dargle begins up in the Wicklow Mountains and finally empties into Irish Sea in Bray Harbor. Another source says the Dargle (a popular pub) was also a holiday haunt of the late eighteenth century Dublin candlemaker and grocer, Waxy O'Connor.
Here are some translations for the lyrics. “Auld one,” or old one, means wife. “Auld lad,” or old lad, means husband. In some versions the word “Uncle” is substituted with the phrase "Young Kill."
Waxie's Dargle
Says my auld one to your auld one
Will you come to the Waxie's dargle
Says your auld one to my auld one
Sure I haven't got a farthing
I've just been down to Monto town
To see Uncle McArdle
But he wouldn't lend me a half a crown
To go to the Waxie's dargle
Chorus:
What'll you have, will you have a pint
Yes, I'll have a pint with you, sir
And if one of us doesn't order soon
We'll be thrown out of the boozer
Says my auld one to your auld one
Will you come to the Galway races
Says your auld one to my auld one
With the price of my auld lad's braces
I went down to Capel Street
To the pawn shop money lenders
But they wouldn't give me a couple of bob
On my auld lad's red suspenders
(chorus)
Says my auld one to your auld one
We've got no beef nor mutton
But if we go down to Monto town
We might get a drink for nothin'
Here's a piece of good advice
I got from an auld fish-monger
When food is scarce and you see the hearse
You'll know you've died of hunger
(chorus)
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To review some the history, the text, or to listen to the melody, check out this pages from the "Songs of England" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts"
- (The Girl I left Behind Me, Version 1) http://www.contemplator.com/england/girl.html
- (The Girl I left Behind Me, Version 2) http://www.contemplator.com/england/girl2.html
- (Waxie's Dargle) http://www.contemplator.com/england/waxie.html
To see a GIF image file of the score of the song, or to download an ABC file of the score, or other notations, visit this mirror site of Digital Tradition - http://sniff.numachi.com/pages/tiGIRLLFT1;ttBRGHTON.html
To see a GIF image file of the score of the song, or to download an ABC file of the score, visit this page of "The Session" - http://www.thesession.org/tunes/display/5418
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