Monday, October 29, 2007

More on Amazing Comet 17P/Holmes

Comet 17P/Holmes just won't stop amazing us. Please check it out if you can. Last week, Comet 17P/Holmes shocked sky watchers around the world with a sudden million-fold increase in brightness. It literally exploded into view, rapidly becoming a naked eye "star" in the constellation Perseus. Following the comet's outburst last week, the comet's coma, or outer cloud of gas and dust, is now physically larger than the planet Jupiter and subtends an angle in the night sky similar to the Moon's Sea of Tranquility, the right eye of the "Man in the Moon."

I have learned that it was an explosion/eruption of gas and dust similar to this that allowed the comet to be discovered in 1892 by British astronomer Edwin Holmes. I also understand that this is an excellent imaging target for off-the-shelf digital cameras and backyard telescopes. At this point, no one knows how large the comet will become.

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 about 7PM and be completely above the horizon just after 8PM. Comet 17P/Holmes should be visible roughly to the East (left) of Epsilon Persei (the thigh of Perseus) which shines at magnitude 2.89.

BACKGROUND: Comet 17P/Holmes was discovered by British 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

Sunday, October 28, 2007

Missing Black Holes Found

Astronomers have discovered hundreds of black holes hiding deep inside dusty galaxies billions of light-years away.

The massive and growing black holes, discovered by NASA's Spitzer and Chandra space telescopes, represent a large fraction of a long-sought missing population. Their discovery implies there were hundreds of millions of additional black holes growing in our young universe, more than doubling the total amount known at that distance.

The discovery reveals that active, supermassive black holes were everywhere in the early universe. The findings are also the first direct evidence that most, if not all, massive galaxies in the distant universe spent their youths building supermassive black holes at their cores.

A Primer on Black Holes and Quasars

A black hole is the common name for an object so dense that not even light can escape its gravity. It is detected by studying its effects on nearby objects and matter (infrared radiation, radio emissions, x-rays, etc.). A supermassive black hole is black hole that has a mass ranging from 100 thousand to over 100 billion solar masses (the mass of the sun). It is currently thought that most, if not all galaxies, including the Milky Way, contain supermassive black holes at their centers.

Those old enough to remember the 1970s may remember Motorola's Quasar brand of color televisions, as well as their slogan: "The quality goes in before the name goes on." Well, the brand name was a reference to the astronomical term.

Many pronounce the word as "QUAY-zar," though some insist that it should be pronounced "QUAH-zar." In any case, the word is a contraction of the phrase "quasi-stellar radio source." The first quasars were discovered in the 1950s using radio telescopes and many quasars were observed just as radio sources with no visible light source. It was not until the 1960s that the radio sources were first linked to visible objects. And the abbreviation "quasar" was first used in a 1964 scientific paper. Astronomers have found that only 10% of quasars actually have a strong radio emission. So the name "quasi-stellar object" or QSO is sometimes used for the majority class of objects that are "radio-quiet." Still, many often refer to all of these objects as quasars.

Today, scientists generally agree that a quasar is the compact doughnut of gas and dust that surrounds a very active supermassive black hole at the center of a young galaxy. As the gas and dust are devoured by the black hole, they heat up and shoot out X-rays. A quasar may release energy in levels equal to the output of hundreds of average galaxies combined. The X-rays can be detected as a general glow in space, but often the quasars themselves can't be seen directly because the surrounding doughnut blocks them from our view.

For decades, a large population of active black holes has been considered missing. Based on studies done about 30 years ago, astronomers knew that there must be more quasars in the universe, but they didn't know where or how to find them until now.

The Research Team

The research team was led by Emanuel Daddi, now of the Commissariat a l'Energie Atomique in France. Daddi began the project while working at the National Optical Astronomy Observatory (NOAO) in Tucson, Arizona before relocating to France last year. Another team member was Mark Dickinson, an astronomer with NOAO. Dickinson led the infrared segment of the investigation using NASA's Spitzer space telescope. Also on the team was David Alexander of Durham University, United Kingdom, and David Elbaz of the Commissariat a l'Energie Atomique. Daddi, Dickinson, Alexander, and Elbaz were co-author of two new papers that will appear in the November 10 issue of The Astrophysical Journal. The team’s results were consistent with those recently obtained by another team led by Fabrizio Fiore of the Osservatorio Astronomico di Roma, Italy. The results of the second team will appear in the Jan. 1, 2008, issue of Astrophysical Journal.

The Observations

The team initially set out to study 1,000 dusty and massive galaxies that were busy making stars. The galaxies were about the same mass as our own spiral Milky Way galaxy, but irregular in shape. Most important, the galaxies were also thought to not have quasars. The galaxies were (and still are) located 9 billion to 11 billion light years away, which meant the team was seeing the galaxies as they were 9 to 11 billion years ago. Since the universe is thought to be about 13.5 billion years old, that would mean the team was looking at a universe that was only 2.5 to 4.5 billion years old, so these 1,000 galaxies would have been in their teenage years - the boom time when the galaxies were growing the most.

When the team examined the galaxies with Spitzer, they noticed that about 200 of the galaxies gave off an unusual amount of infrared light. X-ray data from Chandra, and a technique called "stacking," revealed the 200 galaxies were, in fact, hiding plump quasars. The scientists now think that the quasars heat the dust in their surrounding doughnut clouds, releasing the excess infrared light.

Prior to the investigation, astronomers had only seen the rarest and most energetic black holes from the early universe. But the team’s discovery more than doubles that number of black holes. Some were comparing the experience to having a blindfold removed from their eyes. By projecting their results to the rest of the sky, the team now thinks it has found most of the population of hidden quasars in the early universes.

The Findings

The newfound quasars are helping answer fundamental questions about how massive galaxies evolve. For instance, astronomers have learned that most massive galaxies steadily build up their stars and black holes simultaneously until they get too big and their black holes suppress star formation. It is thought that supermassive black holes have to consume on average about 10 solar masses each year. But that the brightest known quasars have to consume about 1,000 solar masses of material per year. Since they cannot continue at this rate forever, scientists now think that after quasar accretes the surrounding doughnut gas and dust, it settles down to what we consider an ordinary galaxy. Eventually, when the supermassive black holes get “supermassive” enough, they actually prevent new stars from forming, and the galaxy slowly grows dark as the remaining stars die.

The observations also suggest that collisions between galaxies might not play as large a role in galaxy evolution as previously believed. Some had thought that the merging of galaxies was required to begin quasar activity, but they now see that quasars can be active in solitary galaxies.

The Survey

Daddi’s team made their observations as part of the Great Observatories Origins Deep Survey (GOODS), the most sensitive survey to date of the distant universe at multiple wavelengths. GOODS unites extremely deep observations from NASA's Great Observatories (the Spitzer Space Telescope, the Hubble Space Telescope, the Chandra X-ray Observatory), from ESA's XMM-Newton X-ray Observatory, and from the most powerful ground-based facilities, to survey the distant universe to the faintest detectable limits across the broadest range of wavelengths.

For more information on the team’s discovery, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer; and http://chandra.harvard.edu/ and http://www.nasa.gov/mission_pages/chandra/main/index.html.

****************************************

THE SKY THIS WEEK

Oct 28 - Venus at greatest western elongation (46°)

Oct 30 - Mars is 3° south of the Moon

Oct 31 - Neptune is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.

Nov 1 - Mercury is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.

Nov 1, 5:18 P.M (EDT) - Last Quarter Moon

Nov 1 - Comet Arend perihelion (1.924 AU)

Nov 2 - Comet Arend closest approach to Earth (0.999 AU)

Nov 2 - Asteroid 1604 Tombaugh closest approach to Earth (1.881 AU)

Nov 3 - Peak of the Southern Taurid Meteor Shower. This is one of two showers visible in the fall and winter that originate from the constellation Taurus. Both of these showers appear to be caused by Periodic Comet Encke. The other shower is called the Northern Taurid shower The Southern Taurid meteors are visible from September 15 through December 15 with the peak on November 3. The average meteor rate ranges from 5 to 15 per hour. The coordinates for the radiant of the Southern Taurid shower is RA 03hrs 44min, +14°.

Meteors are best viewed from a dark-sky location. Observers in for the duration of the evening, or at least for several hours, should bring along a few things: a sleeping bag or blankets for warmth, a recliner or lawn chair, a hot beverage to help cut the chill, and binoculars to view the smoke trails of just-past meteors.

Nov 3 - Regulus is 0.03° north of the Moon, an occultation when viewed from some locations.

Nov 3 - Saturn is 1.8° north of the Moon

****************************************

THIS WEEK IN HISTORY

Oct 29, 1938 - Orson Welles' Broadcast of the "War of the Worlds"

Oct 30, 1981 - Venera 13 Launch (USSR Venus Lander/Flyby Mission)

Oct 30, 1999 - Discovery of the Los Angeles Meteorite (a Mars Meteorite)

Oct 31, 1936 - 1st Successful Rocket Engine Test in Pasadena, California (JPL's Beginnings)

November 2000 - Discovery of the NWA 480 Meteorite (a Mars Meteorite) in Morocco

Nov 2, 1885 - Harlow Shapley's Birthday

Nov 2, 1917 - 90th Anniversary, Mount Wilson 100-inch Telescope First Light

Nov 2, 2002 - 5th Anniversary, Stardust, Asteroid 5535 Annefrank Flyby

Nov 3, 1905 - August Kopff's Discovery of Asteroid 579 Sidonia

Nov 3, 1957 - 50th Anniversary, Sputnik 2 Launch (Laika Dog)

****************************************

MUSICAL DIVERSION

"The Ash Grove" is one of the few Welsh folk songs that has become known all over the world. The Welsh title is "Llwyn Onn" - "llywn" meaning "grove" and "onn" meaning "ash tree"

"According to Grove's Dictionary of Music and Musicians, a variation of the melody appeared as early as 1728. The song was called "Cease Your Funning" and it was part of the muscal "The Beggar Opera" by John Gay.

The more familiar tune is a very old harp melody that was first published (without words) in the 1802 collection entitled "The Bardic Museumsin" by Edward Jones (called "The King's Harpist"). About four years later the tune finally appeared with words in a collection that was appropriately entitled, "Welsh Melodies with Appropriate English Words."

Like many popular melodies, the tune of "The Ash Grove" has over the years been set to many texts. Some more suitable than others for singing in mixed company.

Among the more suitable texts are the Christian hymns, which include such titles as "Let All Things Now Living," "The Master Hath Come" and "On This Night Most Holy."

There are at least four Welsh texts for "The Ash Grove" and it is difficult to know which of these is truely the original, if any. The text below is one of the more popular of the four. It tells the sad story of a sailor's love for Gwen of Llwyn Onn. After her death, the sailor thinks only on Gwen and on other lost friends and loved ones. The Welsh text is in two stanzas and the English translation is in three, suggesting that either the Welsh language is more compact, or that some poetic license was used in the translation.

The Ash Grove

(Welsh)

Yn Nyffryn Llwyn Onn draw mi welais hardd feinwen
A minnau'n hamddena 'rol byw ar y don;
Gwyn ewyn y lli oedd ei gwisg, a disgleirwen
A'r glasfor oedd llygaid Gwen harddaf Llwyn Onn.
A ninnau'n rhodiana drwy'r lonydd i'r banna,
Sibrydem i'n gilydd gyfrinach byd serch;
A phan ddaeth hi'n adeg ffarwelio a'r wiwdeg,
Roedd tannau fy nghalon yng ngofal y ferch.

Cyn dychwel i borthladd wynebwn y tonnau,
Ond hyfryd yw'r hafan 'rol dicter y don;
Bydd melys anghofio her greulon y creigiau--
Un felly o'wn innau 'rol cyrraedd Llwyn Onn.
A thawel mordwyo wnaf mwyach a Gwenno
Yn llong fach ein bwthyn a hi wrth y llyw;
A hon fydd yr hafan ddiogel a chryno
I'r morwr a'i Wenno tra byddwn ni byw.

(English translation by John Oxenford)

The ash grove, how graceful, how plainly 'tis speaking,
The wind [harp] through it playing has language for me.
Whenever the light through its branches is breaking
A host of kind faces is gazing on me.
The friends of my childhood again are before me,
Each step wakes a memory as freely I roam.
With soft whispers laden its leaves rustle o'er me,
The ash grove, the ash grove again [alone] is my home.

My laughter is over, my step loses lightness,
Old countryside measures steal soft on my ear;
I only remember the past and its brightness,
The dear ones I mourn [long] for again gather here.
From out of the shadows their loving looks greet me
And wistfully searching the leafy green dome,
I find other faces fond bending to greet me,
The ash grove, the ash grove alone is my home.

My lips smile no more, my heart loses its lightness
No dream of my future my spirit can cheer;
I only can brood on the past and its brightness,
The dead I have mourned are again living here.
From ev'ry dark nook they press forward to meet me;
I lift up my eyes to the broad leafy dome,
And others are there looking downward to greet me;
The ash grove, the ash grove alone is my home.


To review some the history, the text, or to listen to the melody, check out this page from the "Songs of Wales" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/wales/ashgrv.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/997

To see and hear more on the hymn, "The Master Hath Come," visit this page of "The Cyber Hymnal" - http://www.cyberhymnal.org/htm/m/a/masthath.htm

For further detailed information about this tune and many different sets of lyrics in English and Welsh go to www.gurman.org/ashgrove

****************************************

Thursday, October 25, 2007

Check Out Comet 17P/Holmes

If you have an opportunity, please check out Comet 17P/Holmes. The comet nucleus (core) appears to be having an outburst of activity. It is possible that the nucleus may be breaking up, but this is not certain. In the last 48 hours the comet has greatly increased in brightness, now visible at magnitude 2.5! Recent reports suggest the coma (the atmosphere of the comet) is expanding and taking on a lopsided shape, perhaps the beginnings of a significant tail.

The coma appears yellow, probably the color of the reflected sunlight. The edges of the comet may appear green which likely signifies an atmosphere rich in diatomic carbon and cyanogen, typical components of greenish comets.

The comet appears just to the East of the constellation Perseus. If you are in the Tampa Bay area, Perseus will rise in the North East about 7PM and be completely above the horizon just after 8PM. Comet 17P/Holmes should be visible roughly to the East (left) of Epsilon Persei (the thigh of Perseus) which shines at magnitude 2.89. In fact, you might mistake the comet for Epsilon Persei because of its brightness.

Comet 17P/Holmes was discovered by British 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 365.25 days); Inclination, 19.1877°; Last perihelion, May 4, 2007; Next perihelion (predicted), March 27, 2014.

For more details, 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/10775326.html

Saturday, October 20, 2007

This week's installment is shifting a bit, moving to cover a week range of Sunday through Saturday in order to better conform to other publications. Because of this, some items from the previous week dated for October 21 are duplicated here for consistency.

****************************************

APOPHIS, FUSE, LIGHT POLLUTION EFFECTS, AND BLACK HOLES

Asteroid Apophis Composition Identified

On October 9, MIT scientists announced they had for the first time determined the composition of an asteroid. The team was lead by Richard P. Binzel, professor of planetary sciences in the Department of Earth, Atmospheric, and Planetary Sciences (EAPS). Binzel worked with graduate students Cristina Thomas and Francesca DeMeo and others. Using the MIT Magellan telescope in Chile and NASA's Infrared Telescope Facility in Hawaii, the team has been learning as much as possible about asteroid 99942 Apophis and other asteroids. In their study, the team used both visible-light and infrared spectroscopy, which means it measured how an object reflects light of different wavelengths in order to determine the object's exact mineral constituents.

The team compared their observations with the many thousands of meteorites collected over the years and found that Apophis was a very good match for a rare meteorite type known as type LL chondrite. Type LL chondrites are low in metal content (about 2% metallic iron). The principle minerals are bronzite and olivine, but some oligoclase is also present. Type LL chondrites make up only 7.2% of all reported meteorite falls. By relying on the laboratory measurements for density and strength of these meteorites, we can infer many of the same properties for Apophis. Binzel presented the new findings October 9 at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society.

Asteroid 99942 Apophis was discovered in 2004. On April 13, 2029, Apophis will come very close to Earth, missing by 22,000 miles. When it returns in 2036, there is a very small possibility - about one chance in 45,000 - that it could strike the earth. An object the size of Apophis, approximately 270 meters across, could destroy an area as large as France, or produce tsunamis over a wide area if it struck at sea. Binzel’s team used Apophis as their first case study to determine the composition of a potentially hazardous asteroid in order better determine how to defend Earth. Their work is sponsored by NASA and the National Science Foundation.

To learn more about NASA’s Near-Earth Asteroid Program, visit: http://neo.jpl.nasa.gov/ and to learn more about MITs Department of Earth, Atmospheric, and Planetary Sciences, visit: http://eapsweb.mit.edu/

Pulling the Fuse on FUSE

This week, scientists and engineers said their formal goodbyes to NASA's Far Ultraviolet Spectroscopic Explorer (FUSE). Since its launch into high Earth orbit on June 24, 1999, FUSE has explored the Universe using the technique of high-resolution spectroscopy in the far-ultraviolet spectral region. As a spectroscopic telescope, FUSE broke starlight down into its constituent spectra, or wavelengths, so scientists could study the chemistry, velocity and temperature of objects and regions invisible to telescopes on the ground. For example, scientists used FUSE to confirm the existence of a halo of hot gas around the Milky Way galaxy -- the exhalations of exploding stars. FUSE also looked for molecular hydrogen on Mars, a remnant of the planet's vanished water.

The Johns Hopkins University (JHU) had the lead role in developing and operating the mission, in collaboration with The University of Colorado at Boulder, The University of California at Berkeley, international partners the Canadian Space Agency (CSA) and the French Space Agency (CNES), and corporate partners. Planning for FUSE began in the early 1980's and some team members have been working on the project since they were JHU graduate students.

FUSE was designed for a three-year mission, but has been running for eight. In that time the mission obtained over 130 million seconds (over 4 years, combined) of observing time. FUSE made observations of 2,800 celestial objects. Then on July 12, the last of the telescope's four troublesome "reaction wheels" ground to a stop, making it impossible to aim at stars and galaxies. Controllers had been creatively solving satellite problems for years in order to extend the mission, but this was the straw that broke the camel's back.

On Thursday, October 18, the FUSE mission terminated science operations and the satellite was shut down. The process was quite involved because the engineers had to overcome all of the safety protocols programmed into the satellite systems. Controllers will continue a near year-long process of monitoring the satellite in order to make sure it "stays dead," so that it will not interfere with any current or future missions that may share the same goals or communication frequencies, etc. By some estimates, FUSE may continue tumbling in orbit for up to 30 years before it re-enters the atmosphere.

To date, more than 1,200 scientific papers have been published with FUSE data, and many more are expected in the future. The mountain of FUSE data is being stored at the Multimission Archive at the Space Telescope Science Institute in Baltimore. The science archive will form the lasting legacy of the FUSE mission. No similar missions are currently planned, so this archive will have to suffice for astronomers for the foreseeable future. To learn more about the FUSE mission, check out the mission home page of the Far Ultraviolet Spectroscopic Explorer: http://fuse.pha.jhu.edu/

David Dunlap Observatory Soon to Go Dark

Thirty-five years ago, University of Toronto (U of T) astronomer Tom Bolton proved the existence of black holes. A few leading astrophysicists had predicted that so-called "black holes" could be created when huge stars die and implode under their own mass. According to theories, these super-dense objects would exert such a powerful gravitational pull that not even light could escape their grasp. Essentially, black holes would be invisible - and that would make it extremely difficult to find one.

Bolton, then 28, spent many long nights at the David Dunlap Observatory in Richmond Hill. He charted the strange movements of a star that appeared to be tugged by an unseen companion. Gases were being sucked off the surface of the star and disappearing into the void of space. He published his findings in 1972, arguing that the only logical explanation was a black hole.

The Dunlap Observatory is a facility of the Department of Astronomy and Astrophysics at the U of T. Opened in 1935, the observatory was a gift to the university by Jessie Dunlap as a memorial to her husband David Alexander Dunlap, who was a mining entrepreneur and astronomy buff. The observatory boasts the largest optical telescope in Canada, measuring 1.88 meters (74 inches) in diameter. At the time of its opening it was the second biggest in the world.

Unfortunately, the historic observatory has fallen victim to the urban sprawl around Toronto. Even with the electronic upgrades done in the 1980s, light pollution has limited the observable reach of the telescope. U of T representatives began considering the sale of the observatory and the surrounding 190-acre property, which had increase in value many times over since the original gift. Unfortunately, under the original terms of the Dunlap gift, the property would revert back to the family of it were no longer used for astronomy. University representative began extensive talks with the Dunlap family.

Finally, in September, U of T announced they would work with the Dunlap heirs to begin the process to establish the Dunlap Institute at U of T’s St. George campus. The institute is planned to be a world-class facility using. The institute will be funded by the Dunlap family through the sale of the existing Dunlap Observatory and the surrounding property. A large portion of the proceeds would be given to create the new Institute, while a smaller portion would be retained by the Dunlap descendants. The proposal for the project goes to the university’s governing council on October 30 for final approval.

The U of T astronomers admit that the old observatory is still useful for examining the stars in our own galactic neighborhood. However, they also explain that in order do groundbreaking the work that changes our understanding of the universe, they must observe the most distant objects. And in order to study the farthest and faintest objects, a bigger telescope in a darker location would be needed. By developing the telescopic equipment, the university hopes to be able to create an observatory powerful enough to look back to virtually the beginning of time.

To learn more about U of T’s David Dunlap Observatory and proposal for the Dunlap Institute, visit the observatory home page: http://www.astro.utoronto.ca/DOD/

Largest Known Stellar Back Hole To Date

Astronomers have located in the nearby galaxy M33 (3 million light years away) an exceptionally massive black hole in orbit around a huge companion star. By combining data from NASA's Chandra X-ray Observatory and the Gemini telescope on Mauna Kea, Hawaii, the mass of the black hole, known as M33 X-7, was determined to be 15.7 times that of the Sun, making M33 X-7 the most massive stellar black hole known. A stellar black hole is formed from the collapse of the core of a massive star at the end of its life. The details of the discovery were published in a paper that appears in the October 18 issue of the journal Nature.

The discovery raised lots of questions about how such a big black hole could have been formed. M33 X-7 orbits a companion star that eclipses the black hole every three and a half days. The companion star also has an unusually large mass, 70 times that of the Sun, making it the most massive companion star in a binary system containing a black hole. Astronomers expect that the companion star will also go supernova, resulting in a pair of black holes.

The properties of the M33 X-7 binary system - a massive black hole in a close orbit around a massive companion star - are difficult to explain using conventional models for the evolution of massive stars. The parent star for the black hole must have had a mass greater than the existing companion in order to have formed a black hole before the companion star.

Such a massive star would have had a radius larger than the present separation between the present star and black hole, so the two stars must have been brought closer while sharing a common outer atmosphere. This process typically results in a large amount of mass being lost from the system, so much that the parent star should not have been able to form a 15.7 solar-mass black hole.

The black hole's original star must have shed gas at a rate about 10 times less than predicted by models before it exploded. If even more massive stars also lose very little material, it could explain the incredibly luminous supernova seen recently as SN 2006gy. The star that created SN 2006gy is thought to have been about 150 times the mass of the Sun when it exploded. It suggests that massive stars use less of their mass toward the end of their lives than it was once thought. This would have a big effect on the black holes eventually created by these stars.

To learn more about the discovery, and about the Chandra X-Ray Observatory check out these websites: http://chandra.harvard.edu/ and http://chandra.nasa.gov/ and to learn more about the Gemini Observatory, check out: http://www.gemini.edu/

****************************************

THE SKY THIS WEEK

Oct 21 - Peak of Orionid meteor shower. Observers under dark skies should see rates of 15 to 20 meteors per hour. The shower should also be strong a few days before and after the peak (about the 19th through the 23rd, called the maximum). This shower is caused by dust from Halley's Comet, which is also responsible for the Eta Aquarid Shower in the spring. Orionid meteors will appear to radiate from a point in the sky between the constellations Gemini and Orion, high in the southern sky. Meteors from the Orionid shower may be visible throughout the month of October and through the first week of November.

Meteors are best viewed from a dark-sky location. Observers in for the duration of the evening, or at least for several hours, should bring along a few things: a sleeping bag or blankets for warmth, a recliner or lawn chair, a hot beverage to help cut the chill, and binoculars to view the smoke trails of just-past meteors.

Oct 22 - Asteroid 2 Pallas is stationary. The body appears motionless in the sky due to the turning point between its direct and retrograde motion.

Oct 22 - Uranus is 1.8° south of Moon

Oct 23 - Mercury is in inferior conjunction

Oct 26, 12:52 AM - Full Moon, the Hunter’s Moon

Oct 26 - Moon at perigee, the point in the Moon's orbit when it is closest to Earth.

Oct 26 - Asteroid 48475 (1991 UD2) Occults HIP 13108, a 5.8 magnitude star

Oct 28 - Venus at its greatest western elongation (46°)

****************************************

THIS WEEK IN HISTORY

Oct 25, 1877 - Henry Russell's 130th Birthday

Oct 21, 1897 - Opening of Yerkes Observatory (110th Birthday). Yerkes Observatory is a facility of the Department of Astronomy and Astrophysics of the University of Chicago. It was established in 1897 on Geneva Lake in Williams Bay, Wisconsin. Until the mid-1960's, Yerkes Observatory housed all of the Department's activities. Today the 77-acre, park-like site in southeast Wisconsin provides laboratory space and access to telescopes for research and instruction. The telescopes at Yerkes include the 40-inch (102 cm) refractor constructed by Alvan Clark and Sons (the largest refractor), a 40-inch (102 cm) reflector, a 24-inch (61 cm) reflector, a 10-inch (25 cm) Cassegrain reflector, and a 7-inch (18 cm) Schmidt camera. To learn more, visit the Yerkes Observatory public home page: http://astro.uchicago.edu/yerkes/

The Yerkes Observatory and its grounds are in serious danger of being sold by the University of Chicago to local developers. To learn what is being done to help save the Yerkes Observatory, and to learn how you can help, visit the organization website, Save Yerkes Observatory: http://www.saveyerkes.com/

****************************************

MUSICAL DIVERSION

"The Minstrel Boy" is an emotionally stirring and inspirational song. It was written by Thomas Moore (1779-1852) who set the words to the melody of an ancient Irish aire called "The Moreen." It is widely thought that Moore composed the song in remembrance of a number of his friends, whom he met while studying at Trinity College, Dublin and who had participated in the 1798 rebellion of the United Irishmen. As the story goes, one friend was wounded, another friend died in prison, and a third was captured and later hung. Yet through it all, Moore refused to testify against his friends.

The song gained widespread popularity and became a favorite of many of the Irish who fought during the United States Civil War. The third first of the song was added at that time by unknown authors.

The song is notably associated with many U.S. organizations that historically had large numbers of members of Irish descent. These organizations include various city police departments and fire departments. The melody is frequently played at funerals of members and/or officers of such organizations who have died or been killed in service, typically on bagpipes. The song is also associated with the Irish Army and with traditionally Irish regiments and/or Irish Brigades found in other armies.

This song is quite popular and has been heard in many movies, such as the 2001 film "Black Hawk Down," and in many television series. Fans of Star Trek may remember that the song's first verse was sung by the character Miles O'Brien (actor Colm Meaney) in the Star Trek: The Next Generation fourth-season episode entitled "The Wounded." During the run of the spin-off series Star Trek: Deep Space Nine the tune became an unofficial theme song for the O'Brien character, and can be heard in several episodes.

The Minstrel Boy

The Minstrel Boy to the war is gone
In the ranks of death you will find him;
His father's sword he hath girded on,
And his wild harp slung behind him;
"Land of Song!" said the warrior bard,
"Tho' all the world betrays thee,
One sword, at least, thy rights shall guard,
One faithful harp shall praise thee!"

The Minstrel fell! But the foeman's chain
Could not bring that proud soul under;
The harp he lov'd ne'er spoke again,
For he tore its chords asunder;
And said "No chains shall sully thee,
Thou soul of love and brav'ry!
Thy songs were made for the pure and free,
They shall never sound in slavery!"

The third verse, added during the 1860s:

The Minstrel Boy will return we pray
When we hear the news, we all will cheer it,
The minstrel boy will return one day,
Torn perhaps in body, not in spirit.
Then may he play on his harp in peace,
In a world such as Heaven intended,
For all the bitterness of man must cease,
And ev'ry battle must be ended.

To review the history, the text, or to listen to the melody, check out this page from the “Songs of Ireland” section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/ireland/minstrel.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/6782

The following link has JPEG image files of an 1895 edition of the score, including a solo line and piano accompaniment. It is two pages in length and presents the first and second verses. The link is on the website called Library Ireland, a free online reference library of Irish material:http://www.libraryireland.com/Irish-Melodies/The-minstrel-boy-1.php

****************************************

Monday, October 15, 2007

DAWN, ENCELADUS, DUST AND PLUTO

Many exciting things are happening in astronomy. Here are just a few.

Dawn is Under the Microscope

Dawn has been getting a check up since its launch on September 27. Members of NASA's Dawn mission control team have been sending commands and checking out spacecraft systems. The first test firing of one of Dawn's three ion engines began Saturday, October 6 and ran for 27 hours as the team evaluated the engine at five different throttle levels ranging from flight idle through full throttle. The test consumed less than .28 kilograms (10 ounces) of the spacecraft's xenon fuel supply -- less than the contents of a can of soda. Dawn's fuel tank carries 425 kilograms (937 pounds) of xenon propellant. Over their lifetime, Dawn's three ion propulsion engines will fire cumulatively for about 50,000 hours (over five years) -- a record for spacecraft. Good engine performance is vital to the success of Dawn's 8-year, 4.9 billion-kilometer (3-billion-mile) journey.

The team will test Dawn for two more months before they consider the spacecraft mission operational. Dawn will begin its exploration of asteroid Vesta in 2011 and the dwarf planet Ceres in 2015. By utilizing the same set of instruments at two separate destinations, scientists can more accurately formulate comparisons and contrasts. Dawn's science instrument suite will measure shape, surface topography, tectonic history, elemental and mineral composition, and will seek out water-bearing minerals. In addition, the team will measure the masses and gravity fields of Vesta and Ceres by monitoring how the Dawn spacecraft orbits the two bodies. For more on Dawn, check out the mission home page: http://dawn.jpl.nasa.gov/ .

Enceladus Jets are Better Understood

A recent analysis of images from NASA's Cassini spacecraft gave conclusive evidence that the observed jets of fine, icy particles spraying from Saturn's moon Enceladus originate from the hottest spots on the moon's "tiger stripe" fractures that straddle the moon's south polar region. The new results were published in the October 11, 2007, issue of the journal Nature.

Since the first images of the Enceladus jets were taken in 2005, imaging scientists suspected these jets, which collectively feed a plume that towers thousands of kilometers, or miles, above the moon, had been coming from the tiger stripes. But this work provides the first conclusive proof, as well as confirming a relationship between the jets and the unusual heat radiating from the fractures.

The scientists also suggest that the character of the jets may change depending on tidal frictional heating within the fractures and its variation over length of the moon's orbit around Saturn. However, more work remains to determine this.

The imaging team was the first of many to suggest that the jets may erupt from pockets of liquid water. This notion, combined with the unusually warm temperatures and the organic material detected in the vapor accompanying the icy particles, lead to the scientist to include Enceladus as one of the Saturnian moons that may contain a habitable zone for life. The next opportunity to learn more will come when Cassini flies through the plumes in March 2008, obtaining additional data about its chemical composition and the nature of its jets.

For more on Enceladus and the rest of the Saturn system, check out the mission home page: http://www.nasa.gov/cassini . You can find great information and graphics at these websites:http://saturn.jpl.nasa.gov/ , http://www.nasa.gov/cassini and http://ciclops.org/ .

Dust from Black Holes

New findings from NASA's Spitzer Space Telescope suggest that space dust – the same stuff that makes up living creatures and planets – was manufactured in large quantities in the winds of black holes that populated our early universe. The details will be published in an upcoming issue of the Astrophysical Journal Letters. The lead author is Ciska Markwick-Kemper of the University of Manchester, U.K.

Space dust is essential to the formation of planets, stars, galaxies and even life as we know it. The dust in our corner of the universe came from dying stars that were once a lot like our sun. But, when the universe was less than a tenth of its present age of 13.7 billion years, sun-like stars hadn't been around long enough to die and make dust. So what was making the dust when the universe was young?

Many have long thought that short-lived, massive exploding stars, or supernovae, might be the source, while others have suggested that a type of energetic, growing supermassive black hole, called a quasar, could be a contributing factor. A quasar consists of a supermassive black hole surrounded by a dusty doughnut-shaped cloud that feeds it. Theoretically, dust could form in the outer portion of the winds that slowly blow away from this doughnut cloud.

Markwick-Kemper and her team decided to test the quasar theory by investigating a quasar, called PG2112+059, located in the center of a galaxy about 8 billion light-years way. They found a mix of the ingredients that make up glass, sand, marble and even rubies and sapphires. While the mineral constituting glass was expected, the minerals for sand, marble and rubies were a surprise. Why? These minerals are not typically detected floating around galaxies, suggesting they could have been freshly formed in the winds rushing away from the quasar.

For instance, the ingredient that makes up sand, crystalline silicate, doesn't survive for long free-floating in space. Radiation from stars zaps the minerals back to an amorphous, glass-like state. The presence of crystalline silicate therefore suggests something – possibly the quasars winds – is churning out the newly made substance. For graphics and more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Pluto Family Portrait

On October 12, astronomers announced that new images taken of the Pluto system are the sharpest ever made and 20 times brighter than those taken 30 years ago when Pluto’s large moon Charon was discovered. The images are expected to bring astronomers closer to estimating the sizes of Pluto's satellites, Nix, Hydra and Charon.

The images were taken by astronomer David Tholen using one of Mauna Kea’s twin Keck telescopes, and utilizing the Keck’s adaptive optics system in order to compensate for turbulence in Earth’s atmosphere. The work was done in early September, when Pluto was at its maximum brightness. Tholen took 16 images and combined them into a single picture.

The moons Nix and Hydra, discovered in 2005 with the Hubble Space Telescope, are currently estimated to be less than 62 miles in diameter. The moon Charon is estimated to be 753 miles (1,212 kilometers) and Pluto is estimated to be 1,429 miles. Many more images of the Pluto system will be taken over the next several lunar orbits around Pluto. This will allow astronomers to determine precise positions of the satellites, and thereby determine precise masses for Nix and Hydra.

The more definitive measurements are important for scientists planning the 2015 flyby of Pluto with NASA's New Horizons spacecraft. One of the current astronomy goals is to determine the proper exposure times for the New Horizons instruments before their arrival. To learn more about the New Horizons mission to Pluto and the Kuiper belt, check out the mission hope page: http://pluto.jhuapl.edu/

****************************************

THE SKY THIS WEEK

Here are some observing highlights for the week. These events are given from the perspective of observers in the northern hemisphere. No offence to southern-hemisphere folks, it's just because of where I live.

Oct 15, After Sunset - Moon, the planet Jupiter and the star Antares appear very close together.

Oct 19, 4:33 am EDT - first-quarter Moon

Oct 21 – Peak of the Orionid Meteor Shower. This shower is caused by dust from Halley's Comet, which is also responsible for the Eta Aquarid Shower in the spring. Meteors from the Orionid shower may be visible throughout the month of October and through the first week of November. The maximum will probably last from the 19th through the 23rd, with the peak around the 22nd. At its height the shower should produce 15 to 20 meteors per hour. The meteors will appear to originate from a point in the sky between the constellations Gemini and Orion, high in the southern sky during the October evenings.

Meteors are best viewed from a dark-sky location. Observers in for the duration of the evening, or at least for several hours, should bring along a few things: a sleeping bag or blankets for warmth, a recliner or lawn chair, a hot beverage to help cut the chill, and binoculars to view the smoke trails of just-past meteors.

****************************************

THIS WEEK IN HISTORY

Oct 15, 1997 - Cassini launch (10th anniversary). Ten years ago, a Titan IV rocket launched the Cassini spacecraft on its mission to Saturn. To learn about the work currently don by Cassini, visit the NASA Saturn home page: http://saturn.jpl.nasa.gov/

Oct 18, 1967 - Venera 4, Venus Landing (40th Anniversary). The Soviet spacecraft Venera 4 (Venus 4) launched June 12, 1967 (UTC) with an announced mission to study the Venusian atmosphere. On October 18, 1967, the spacecraft entered the Venusian atmosphere and released two thermometers, a barometer, a radio altimeter, and atmospheric density gauge, 11 gas analyzers, and two radio transmitters operating in the DM waveband. The main bus, which had carried the capsule to Venus, carried a magnetometer, cosmic ray detectors, hydrogen and oxygen indicators, and charged particle traps. The spacecraft braked and then deployed a parachute system after entering the Venusian atmosphere. Signals were returned by the spacecraft until it reached an altitude of 24.96 km.

Oct 19, 1967 - Mariner 5, Venus Flyby (40th Anniversary). The NASA spacecraft Mariner 5 (also called Mariner Venus ’67) was launched June 14, 1967 (UTC). Mariner 5 was a refurbished backup spacecraft for the Mariner 4 mission and was converted from a Mars mission to a Venus mission. The spacecraft was fully attitude stabilized, using the sun and Canopus as references. A central computer and sequencer subsystem supplied timing sequences and computing services for other spacecraft subsystems. The spacecraft passed 4,000 km from Venus on October 19, 1967. The spacecraft instruments measured both interplanetary and Venusian magnetic fields, charged particles, and plasmas, as well as the radio refractivity and UV emissions of the Venusian atmosphere.

Oct 20, 1632 - Birth of Christopher Wren (375th Birthday). Sir Christopher Wren, born Oct. 20, 1632, East Knoyle, Wiltshire, England, died Feb. 25, 1723, London. Designer, astronomer, geometrician, and the greatest English architect of his time. Wren designed 53 London churches, including St. Paul's Cathedral, as well as many secular buildings of note. He was a founder of the Royal Society (president 1680–82), and his scientific work was highly regarded by Sir Isaac Newton and Blaise Pascal. He was knighted in 1673.

Oct 21, 1897 - Opening of Yerkes Observatory (110th Birthday). Yerkes Observatory is a facility of the Department of Astronomy and Astrophysics of the University of Chicago. It was established in 1897 on Geneva Lake in Williams Bay, Wisconsin. Until the mid-1960's, Yerkes Observatory housed all of the Department's activities. Today the 77-acre, park-like site in southeast Wisconsin provides laboratory space and access to telescopes for research and instruction. The telescopes at Yerkes include the 40-inch (102 cm) refractor constructed by Alvan Clark and Sons (the largest refractor), a 40-inch (102 cm) reflector, a 24-inch (61 cm) reflector, a 10-inch (25 cm) Cassegrain reflector, and a 7-inch (18 cm) Schmidt camera. To learn more, visit the Yerkes Observatory public home page: http://astro.uchicago.edu/yerkes/

The Yerkes Observatory and its grounds are in serious danger of being sold by the University of Chicago to local developers. To learn what is being done to help save the Yerkes Observatory, and to learn how you can help, visit the organization website, Save Yerkes Observatory: http://www.saveyerkes.com/

****************************************

MUSICAL DIVERSION: HEART OF OAK

Heart of Oak is an 18th century song of the sea. The tune was written by Dr. William Boyce (1711-1779). The English words were written by the famous actor David Garrick (1716-1779) in 1759. Garrick is also credited with the theatrical blessing, "Break a Leg" as he was reportedly so involved in his performance of Richard III that he did not notice the pain of a fracture he incurred.

There is also an American set of lyrics, called The Liberty Song.

Heart of Oak

Come cheer up, my lads! 'tis to glory we steer,
To add something more to this wonderful year;
To honour we call you, not press you like slaves,
For who are so free as the sons of the waves?

Chorus:

Heart of oak are our ships, heart of oak are our men;
We always are ready, steady, boys, steady!
We'll fight and we'll conquer again and again.
We ne'er see our foes but we wish them to stay,
They never see us but they wish us away;
If they run, why we follow, and run them ashore,
For if they won't fight us, we cannot do more.

(Chorus)

They swear they'll invade us, these terrible foes,
They frighten our women, our children, and beaus;
But should their flat bottoms in darkness get o'er,
Still Britons they'll find to receive them on shore.

(Chorus)

We'll still make them fear, and we'll still make them flee,
And drub 'em on shore, as we've drubb'd 'em at sea;
Then cheer up, my lads! with one heart let us sing:
Our soldiers, our sailors, our statesmen and Queen.

(Chorus)

----------

Many versions of these words have developed over the years. Fans of Walt Disney motion pictures may recall that actors Peter Ustinov, Dean Jones and Suzanne Pleshette sung a version in the 1968 Disney film "Blackbeard's Ghost." And fans of the science fiction television series "Star Trek: The Next Generation" may remember an episode from the third season, entitled "Alegience," in which another version was sung. Below is the first verse and the chorus sung in that episode.

Come, cheer up, my lads, 'tis to glory we steer,
To find something new in this wonderful year;
To honour we call you, as freemen not slaves,
For who are so free as the sons of the waves?

Chorus:

Heart of oak are our ships, jolly tars are our men,
we always are ready; Steady, boy, steady!
We'll fight and we'll conquer again and again!

In the above chorus, the word "tar" is a slag term that was used for a sailor. Their hats and clothes were treated with tar to waterproof them. The tar-impregnated cloth, or tarpaulin, provided protection in harsh conditions. Because of this, a sailor was called a "tarpaulin," or "tar" for short. Fans of Gilbert and Sullivan may remember a song from the musical "HMS Pinafore" entitled "A British Tar."

To review the history, the text, or to listen to the melody, check out this page from the "Songs of the Sea" section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" - http://www.contemplator.com/england/heartoak.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/tiHEARTOAK;ttHEARTOAK.html

****************************************

Sunday, October 07, 2007

METEORS IN THE NEWS

Meteors have certainly been in the news in recent weeks. If you have missed these stories, here is a recap.

The Peruvian Meteorite, September 16

Late Saturday night, September 16th, an orange fireball streaked across the Andean sky and crashed into a muddy field near Carancas, a sparsely populated highland wilderness about 6 miles from Lake Titicaca on the Peruvian border with Bolivia. The water-filled elliptical crater was 42 feet wide and 15 feet deep, but there was no immediate sign of wreckage or meteorite fragments. Over the next few days roughly 150 to 200 visitors to the crater reported smelling a foul stench and exhibited symptoms of dizziness, nausea and dermal injuries.

By September 21, verification of the impact was found in the South American seismic records. The impact registered a magnitude-1.5 tremor, a force as great as an explosion of 4.9 tons of dynamite. Also, and iron-rich magnetic fragment measuring 3 inches in length was recovered from the site.

By September 24, Peru's Mining, Metallurgy, and Geology Institute confirmed that the impact site coincided with a natural underground deposit of arsenic, and that visitors to the crater had inhaled arsenic fumes which, in addition to the excitement of the of the event for the local residents, would certainly have contributed to the symptoms of headache and nausea. As another item of interest, one local astronomer noted that this was the first confirmed Peruvian meteorite fall since June of this year, when another meteorite fell in the Arequipa province.

Finland Superbolide, September 28

Late Friday night, September 28th, a fireball streaked over Finland. Nicknamed the "super-meteor," the object was reported to be a superbolide, a fireball more than 100 times brighter than a full moon, and the brightest seen over Finland in more than 30 years. The meteoroid entered the atmosphere over Northern Ostrobothnia, passed over much of northern and eastern Finland and then exploded in mid-air. No fragments had been recovered as of this writing. Local astronomers think the meteoroid had a mass of approximately 200 kilograms and that the meteor was not part of any known annual meteoroid stream.

Minnesota/Iowa Fireball, October 3

On Wednesday, October 3rd just after 2pm, residents in Minnesota, Iowa and western Wisconsin reported seeing an orange and yellow fireball flash through a clear blue sky traveling from the northeast to the southwest. Some also reported hearing loud booms.

Early reports connected the fall with a wooden pallet found on a Minnesota interstate about that time, but law enforcement officials later assured the public that the pallet most likely fell from a truck on the roadway.

Because of how bright the object appeared to be in the middle of the day, local astronomers speculated that it was at least the size of a pea.

Is this a Meteor Increase?

I am certain there are many who see these news stories and wonder whether the rate of meteor falls is increasing. To the wondering, let me assure you that this is not the case. Because of the Earth’s proportion of water surface area to land surface area, and because much of Earth’s land masses have populations concentrated in specific areas, most of the fireballs and meteorite impacts go unnoticed by the general population.

Near-Earth Objects

These meteors, fireballs and superbolides are actually Near-Earth objects that, well, got very near the earth. Near-Earth Objects, or NEOs, are comets and asteroids that have been nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth's neighborhood. The comets originally formed in the cold outer planetary system and are composed mostly of water ice with embedded dust particles. The asteroids formed in the warmer inner solar system between the orbits of Mars and Jupiter, and they are composed mostly of rock and metal.

Because they are the primitive, leftover building blocks of the solar system formation process, comets and asteroids offer clues to the chemical mixture from which the planets formed some 4.6 billion years ago. If we wish to know the composition of the primordial mixture from which the planets formed, then we must determine the chemical constituents of the leftover debris from this formation process - the comets and asteroids.

On a daily basis, about one hundred tons of interplanetary material drifts down to the Earth's surface. Most of the smallest particles are the tiny dust grains released by comets as their ices vaporize in the solar neighborhood. The vast majority of the larger material originates as the collision fragments of asteroids that ran into one another many, many years ago.

About once every 100 years, rocky or iron asteroids larger than about 50 meters are expected to reach the Earth's surface and cause local disasters or produce the tidal waves that can inundate low lying coastal areas. On an average of every few hundred thousand years or so, asteroids larger than a kilometer could cause global disasters. In this case, the impact debris would spread throughout the Earth's atmosphere so that plant life would suffer from acid rain, partial blocking of sunlight and from the firestorms resulting from heated impact debris raining back down upon the Earth's surface.

Since their orbital paths often cross that of the Earth, collisions with near-Earth objects (NEOs) have occurred in the past and we should remain alert to the possibility of future close Earth approaches. It seems prudent to mount efforts to discover and study these objects, to characterize their sizes, compositions and structures and to keep an eye upon their future trajectories.

No one should be overly concerned about an Earth impact of an asteroid or comet. The threat to any one person from auto accidents, disease, other natural disasters and a variety of other problems is much higher than the threat from NEOs. Over long periods of time, however, the chances of the Earth being impacted are not negligible so that some form of NEO insurance is warranted. At the moment, our best insurance rests with the NEO scientists and their efforts to first find these objects and then track their motions into the future. We need to first find them, and then keep an eye on them.

As of October 2, 2007, 4853 Near-Earth objects (NEOs) have been discovered. 724 of these NEOs are asteroids with a diameter of approximately 1 kilometer or larger. Of this group, 874 have been classified as potentially hazardous asteroids, or asteroids that have a chance in some distant orbit to come very close to Earth.

To learn more about NEOs and about the tremendous NEO searches that are currently underway, please visit the home page of the NASA Near-Earth Object Program: http://neo.jpl.nasa.gov/

****************************************

THE SKY THIS WEEK

Here are some observing highlights for the week. These events are given from the perspective of observers in the northern hemisphere. No offence to southern-hemisphere folks, it's just because where I live.

October 8, Dawn - Venus, Saturn, and Regulus shine above the crescent Moon in the east.

October 8, 2007 - Peak of the Draconid Meteor Shower. Also called the October Draconids and the Giacobinids, this shower is caused by dust from Comet Giacobini-Zinner. Meteors from the October Draconid shower may be visible from October 7 to 10. The shower peaks annually on October 8/9. The rate of the shower is variable and the peak lasts only a few hours. This shower gives a good display only when the parent comet returns to perihelion, which is every 6.5 years. The meteors will appear to originate from a point in the sky near the head of the constellation Draco, the Dragon. Meteors are best viewed from a dark-sky location. Observers in for the duration of the evening, or at least for several hours, should bring along a few things: a sleeping bag or blankets for warmth, a recliner or lawn chair, a hot beverage to help cut the chill, and binoculars to view the smoke trails of just-past meteors.

October 9, 2007 - Venus is 3 degrees south of the star Regulus

October 11, 2007, 1:01 AM - New Moon

October 12, 2007 - Mercury stationary - The body appears motionless in the sky due to the turning point between its direct and retrograde motion.

October 12, 2007 - Mercury is 1.3 degrees north of the Moon

October 13, 2007 - Moon at apogee, the point in the Moon's orbit when it is farthest from Earth.

Terminology Notes:

Degree (°) - one three hundred sixtieth (1/360) of a circle

****************************************

THIS WEEK IN HISTORY

October 9, 1604, Kepler's Nova First Recorded – “Kepler's Nova” was thought at the time to be a "new star," but we now understand that it was a violently exploding star, or supernova. Also called “Kepler's Star,” or “Kepler's Supernova,” it is one of the few supernovae known to have occurred within the Milky Way Galaxy. Several astronomers around Europe noticed the new star about the same time, but the first to record its appearance was Jan Brunowski, assistant to German mathematician, astronomer and astrologer Johannes Kepler (1517-1634) who was working in Prauge. Kepler did not see the new star himself until October 17. Among his other maladies, Kepler suffered from weak eyesight and crippled hands, the effects of smallpox as a child. While this limited his observational skills, it did not diminish his fascination of the heavens, which he learned at a very early age from his mother. As the Imperial Mathematician, Kepler was able to perform extensive studies of the new star with the support and protection of Holy Roman Emperor Rudolph II (1552-1612) who was also living in Prague. When it was first observed, the new star was as bright as Mars, but within a few days it grew to its greatest brightness, estimated to be magnitude -2.5, even brighter than Jupiter. Kepler studied the new star until early 1606 when it had faded until it was no longer visible to the unaided eye. Many people at the time thought the new star held important implications for several areas of interest, including astrology, astronomy, chronology and theology. In 1606, Kepler published his observations and his thoughts in is comprehensive book, "De stella nova" (the new star). Kepler's work proved that the supernova was actually in the heavens and not just a phenomenon in Earth’s atmosphere. Like the discovery of Tycho's Nova years earlier, Kepler's Nova provided evidence that the stars were not perfect and unchanging. Astronomers today more formally refer to “Kepler’s Nova” as Supernova Remnant 1604 (SNR 1604). It is located in the constellation Ophiuchus at stellar coordinates RA 17 hours 30.6 minutes, Dec -21 degrees 29 minutes; distance, less than 20,000 light-years. To date, astronomers have not found the core of the exploded star (a stellar remnant), but they can see a nebula at the position where the supernova occurred. It is especially noticeable in the X-ray portion of the spectrum.

October 9, 1992, Peekskill Meteorite - A meteorite weighing 27.3 pounds slammed a hole through the trunk portion of a red 1980 Chevy Malibu then owned by Michelle Knapp in Peekskill, New York. The hole just missed the car's fuel tank. Prior to the impact, thousands of people in neighboring states heard the sonic booms and watched the greenish fireball for over 40 seconds it traveled north-northeast for about 700 to 800 kilometers (435 to 497 miles). It was later determined from the fireball path that the object had been orbiting the sun prior to the impact. Following the event, the car was purchased by a rock collector and became an attraction at national rock and meteorite conventions. (URL: http://www.nyrockman.com/peekskill.htm)


****************************************

STARS AND BARLEYCORNS

With all of this talk about falling stars and new stars, I couldn't help thinking about a folksong with a tune that has an uncertain national heritage (possibly English or Scottish), but that has been adopted into the English, Scottish and Irish repertoire of folksongs.

"The Star of the County Down" is a composition of the early 20th century. The lyric was written by Cathal McGarvey. He originally set the words to the tune "Gilderoy," which appeared with other songs as early as 1707. However, the tune best known today with "County Down" is another that apparently is even older (first time in print around 1635). This tune has been used for numerous songs, including "Divers and Lazarus" (Dives and Lazarus), "The Murder of Maria Martin," and "Claudy Banks." In 1906, composer Ralph Vaughan Williams arranged a hymn tune based on this melody that is sometimes called "Kingsford." The tune has been used for several English and American Hymns and Carols, including the hymn entitled, "O Sing a Song of Bethlehem." When sung with "County Down," the second half of the tune (the "B" part, as musicians would say) for the chorus.

The Star of the County Down

Near Banbridge town, in the County Down
One morning in July
Down a boreen green came a sweet colleen
And she smiled as she passed me by.
She looked so sweet from her two white feet
To the sheen of her nut-brown hair
Such a coaxing elf, I'd to shake myself
To make sure I was standing there.

Chorus:

From Bantry Bay up to Derry Quay
And from Galway to Dublin town
No maid I've seen like the sweet colleen
That I met in the County Down.

As she onward sped I shook my head
And I gazed with a feeling rare
And I said, says I, to a passerby
"who's the maid with the nut-brown hair?"
He smiled at me, and with pride says he,
"That's the gem of Ireland's crown.
She's young Rosie McCann from the banks of the Bann
She's the star of the County Down."

(Chorus)

I've travelled a bit, but never was hit
Since my roving career began
But fair and square I surrendered there
To the charms of young Rose McCann.
I'd a heart to let and no tenant yet
Did I meet with in shawl or gown
But in she went and I asked no rent
From the star of the County Down.

(Chorus)

At the crossroads fair I'll be surely there
And I'll dress in my Sunday clothes
And I'll try sheep's eyes, and deludhering lies
On the heart of the nut-brown rose.
No pipe I'll smoke, no horse I'll yoke
Though with rust my plow turns brown
Till a smiling bride by my own fireside
Sits the star of the County Down.

(Chorus)

----------

To review the history, the text, or to listen to the melody, check out
this page from the Irish Folk Music section of "Contemplations from the Marianas Trench - Music and Deep Thoughts" -
http://www.contemplator.com/ireland/star.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/4320

To see and hear more on the hymn, "O Sing a Song of Bethlehem," visit this page of "The Cyber Hymnal" -
http://www.cyberhymnal.org/htm/o/s/osingson.htm


Still with me? Good! Do remember me mentioning something about barleycorns? Well, here is the tie-in for that. When the tune was published around 1635 it was used as the melody for an even older English folksong called "John Barleycorn." One early version of the text appears in the Bannatyne Manuscript of 1568.

In the song, the character "John Barleycorn" is a personification of barley, an important cereal crop, and the foundation for alcoholic beverages such as beer and whisky. In the song, John Barleycorn suffers attacks, death, and indignities that correspond to the various stages of barley cultivation, reaping and malting. In fact, when author Jack London published in 1913 his autobiographical novel on his struggles with alcoholism, London entitled the book, John Barleycorn.

Some interpret the song as representing a pagan rite. Others suggest that an early form of the song may have been used by the early church in Saxon England to ease the conversion of pagans to Christianity, reasoning that John Barleycorn represented the pagan ideology of nature cycles, spirits, the harvest, and perhaps also human sacrifice, but that the song was Christianized in order to show John Barleycorn as a Christ-like figure. A popular hymn, "We Plough the Fields and Scatter", is often sung at Harvest Festival to the same tune. Below is a version of the song that was collected by poet Robert Burns and first published in 1782.

John Barleycorn

There was three kings into the east,
Three kings both great and high,
And they hae sworn a solemn oath
John Barleycorn should die.

They took a plough and plough'd him down,
Put clods upon his head,
And they hae sworn a solemn oath
John Barleycorn was dead.

But the cheerful Spring came kindly on'
And show'rs began to fall;
John Barleycorn got up again,
And sore surpris'd them all.

The sultry suns of Summer came,
And he grew thick and strong:
His head weel arm'd wi pointed spears,
That no one should him wrong.

The sober Autumn enter'd mild,
When he grew wan and pale;
His bendin joints and drooping head
Show'd he began to fail.

His colour sicken'd more and more,
He faded into age;
And then his enemies began
To show their deadly rage.

They've taen a weapon, long and sharp,
And cut him by the knee;
They ty'd him fast upon a cart,
Like a rogue for forgerie.

They laid him down upon his back,
And cudgell'd him full sore.
They hung him up before the storm,
And turn'd him o'er and o'er.

They filled up a darksome pit
With water to the brim,
They heav'd in John Barleycorn –
There, let him sink or swim!

They laid him upon the floor,
To work him farther woe;
And still, as signs of life appear'd,
They toss'd him to and fro.

They wasted o'er a scorching flame
The marrow of his bones;
But a miller us'd him worst of all,
For he crush'd him between two atones.

And they hae taen his very hero blood
And drank it round and round;
And still the more and more they drank,
Their joy did more abound.

John Barleycorn was a hero bold,
Of noble enterprise;
For if you do but taste his blood,
'Twill make your courage rise.

'Twill make a man forget his woe;
'Twill heighten all his joy:
'Twill make the widow's heart to sing,
Tho the tear were in her eye.

Then let us toast John Barleycorn,
Each man a glass in hand;
And may his great posterity
Ne'er fail in old Scotland!

****************************************