The Gould Belt Shaped by Dark Matter
Within our Milky Way Galaxy, our sun is part of an area of space known as the Gould Belt, containing a swirl of stars. This partial ring is about 3,000 light-years across and is tilted toward the galactic plane by about 16 to 20 degrees. The Gould Belt is named after American astronomer Benjamin Apthorp Gould (1824-896), who first identified it in 1879. The Gould Belt contains many relatively young stars--perhaps 2 million of them are less than 60 million years old. While our sun is part of the Gould Belt, it is much older--with an estimated age of 4.6 billion years.
In 1997, astronomer Wolfgang G. L. Pöppel of Argentine Institute of Radio Astronomy noted that using the common explanations, astronomers could not explain where all of the Gould Belt’s young stars came from. Pöppel thought that, since these young stars surround our own sun, it might be nice for us to know how they came to be.
In a study published earlier this year, astrophysicist Kenji Bekki of the University of New South Wales, Australia, suggests that within the last 60 million years, this area of our galaxy was struck by a huge, invisible wrecking ball made of a clump of dark matter--mysterious particles created in the aftermath of the Big Bank. The clump proposed to have affected this area would have the mass of 10 million suns. The impact resulted in the Gould Belt and its young stars.
So far, astronomers have only detected dark matter by its gravitational pull on galaxies. Because it does not emit or reflect light, dark matter is impossible to see with optical telescopes. This leads astronomers to believe that the bulk of dark matter is so-called “weakly-interacting massive particles” (WIMPS). These WIMPS are exotic particles much like neutrinos that only rarely interact electromagnetically with normal atoms. Despite its invisibility, the observed gravitational pull of dark matter suggests that there is about five times more of it than what we consider to be normal matter--the stuff that makes up planets, stars and us.
Bekki’s study proposes that the Gould Belt was one of the stellar substructures that were formed from high-speed, off-center collisions between giant clouds of gas and dust and clumps of dark matter, both of which are orbiting the Galaxy. Bekki’s computer modeling shows that the Gould Belt could have been created within 45 million years.
Bekki’s study also suggests that, because of the gravitation effects of the dark matter at the time of the collision, the dark matter may be responsible for perturbing the orbits of the objects in the Kuiper belt, causing them to fall toward the sun and creating a wave of comets in the inner solar system over the last several million years.
Bekki admits that these are speculations. However, he notes that if the Milky Way has 20 dark matter clumps surrounding it, Bekki reasons that a Gould Belt-like ring of stars would be likely to form from dark matter collisions every billions years or so, and that about one tenth of one percent of the stars in our galaxy may have been started in this way.
To learn about Bekki’s study and about dark matter, check out these links:
“Dark Impact and Galactic Star Formation: Origin of the Gould Belt.” Submitted June 28, 2009. Kenji Bekki. arXiv.org, Cornell University Library.
http://arxiv.org/abs/0906.5117
University of New South Wales, Australia
http://www.unsw.edu.au/
Argentine Institute of Radio Astronomy (Instituto Argentino de Radioastronomía)
http://www.iar.unlp.edu.ar/
Dark Matter. NASA’s Imagine the Universe Web Site.
http://imagine.gsfc.nasa.gov/docs/science/know_l1/dark_matter.html
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Saturday, October 31, 2009
Friday, October 30, 2009
GRB 090423 is Oldest and Most Distant Object Yet Discovered
Back on April 23 of this year, NASA’s Swift telescope detected a gama-ray burst (GRB), specifically documented as GRB 090423. About 20 minutes after the burst, one team led by UK astronomer Nial Tanvir began observations using the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea, Hawaii. About 14 hours after the burst, another team led by Italian astronomer Ruben Salvaterra began their own observations using the Telescopio Nazionale Galileo (TNG) on La Palma, in the Canary Islands. The both teams were able to observe the afterglow for 10 days.
A GRB is the most powerful explosion since the Big Bang. GRBs occur somewhere in our sky approximately once per day and are brief, but intense, flashes of gamma radiation. They last from a few milliseconds to a few hundred seconds. GRBs are thought to be associated with the cataclysmic death of a massive star, and are thought to be triggered by the center of the star collapsing to form a black hole.
The two teams have reported the results of their careful study of GRB 090423. Their results indicate that the star that collapsed was 13.1 billion light-years away. The distance suggests that the star collapsed roughly 625 million years after the Big Bang. This is the oldest and most distant celestial object in the known universe. If the two teams’ results are correct it would suggest that massive stars were being born and dying as early as about 625 million years after the Big Bang.
Follow-up studies are planned for next year. Astronomers will use the Hubble Space Telescope to try to locate the distant and early galaxy from which the GRB came. For more information on this event, and for more information on the referenced observatories, check out these links:
Bursting at High Redshift. Editor’s Summary. October 29, 2009, Nature.com.
http://www.nature.com/nature/journal/v461/n7268/edsumm/e091029-06.html
Stellar Blas is Record-Breaker. Victoria Gill. October 28, 2009. BBC News.
http://news.bbc.co.uk/2/hi/science/nature/8329865.stm
NASA’s Swift Gama-Ray Burst Mission Home Page
http://heasarc.nasa.gov/docs/swift/swiftsc.html
United Kingdom Infra-Red Telescope (UKIRT)
http://www.jach.hawaii.edu/UKIRT/
Telescopio Nazionale Galileo (TNG)
http://www.tng.iac.es/
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Back on April 23 of this year, NASA’s Swift telescope detected a gama-ray burst (GRB), specifically documented as GRB 090423. About 20 minutes after the burst, one team led by UK astronomer Nial Tanvir began observations using the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea, Hawaii. About 14 hours after the burst, another team led by Italian astronomer Ruben Salvaterra began their own observations using the Telescopio Nazionale Galileo (TNG) on La Palma, in the Canary Islands. The both teams were able to observe the afterglow for 10 days.
A GRB is the most powerful explosion since the Big Bang. GRBs occur somewhere in our sky approximately once per day and are brief, but intense, flashes of gamma radiation. They last from a few milliseconds to a few hundred seconds. GRBs are thought to be associated with the cataclysmic death of a massive star, and are thought to be triggered by the center of the star collapsing to form a black hole.
The two teams have reported the results of their careful study of GRB 090423. Their results indicate that the star that collapsed was 13.1 billion light-years away. The distance suggests that the star collapsed roughly 625 million years after the Big Bang. This is the oldest and most distant celestial object in the known universe. If the two teams’ results are correct it would suggest that massive stars were being born and dying as early as about 625 million years after the Big Bang.
Follow-up studies are planned for next year. Astronomers will use the Hubble Space Telescope to try to locate the distant and early galaxy from which the GRB came. For more information on this event, and for more information on the referenced observatories, check out these links:
Bursting at High Redshift. Editor’s Summary. October 29, 2009, Nature.com.
http://www.nature.com/nature/journal/v461/n7268/edsumm/e091029-06.html
Stellar Blas is Record-Breaker. Victoria Gill. October 28, 2009. BBC News.
http://news.bbc.co.uk/2/hi/science/nature/8329865.stm
NASA’s Swift Gama-Ray Burst Mission Home Page
http://heasarc.nasa.gov/docs/swift/swiftsc.html
United Kingdom Infra-Red Telescope (UKIRT)
http://www.jach.hawaii.edu/UKIRT/
Telescopio Nazionale Galileo (TNG)
http://www.tng.iac.es/
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Thursday, October 29, 2009
Indonesian Bolide of October 8
Back on Thursday, October 8, around 11 am local time, the people of the coastal town of Bone on the island of Sulewesi, Indonesia, were frightened by thunderous sounds and shaking walls. The people rushed out of their homes, thinking they were in the middle of yet another earthquake. They were met by the sight of a twisting trail of debris in the sky. What they had experienced was in fact the result of an exploding fireball, which is called a bolide.
The bolide was caused by an asteroid with an estimated width of about 10 meters (33 feet). Atmospheric pressure caused it to explode, releasing an amount of energy equivalent to a small atomic bomb. The explosion triggered infrasound sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) more than 10,000 km away. Analysis of the infrasound data revealed an explosion at latitude 4.5˚ S, longitude 120˚ E, close to Bone, with a yield of about 50 kilotons (100,000 pounds) of TNT, about two or three times the power of World War II-era atomic bombs.
The asteroid that caused the blast was not known to astronomers before the event. According to statistical studies of the near-Earth asteroid population, such objects are expected to collide with Earth on average every 2 to 12 years.
Those are just the barest of details, but I thought I would share. To get first-hand information on this event, check out these links:
YouTube Video of Local News Broadcast
http://www.youtube.com/watch?v=yeQBzTkJNhs&videos=jkRJgbXY-90
October 8th Article by the Jakarta Globe
http://thejakartaglobe.com/home/mysterious-explosion-panics-locals-in-south-sulawesi-police-still-investigating/334246
October 8th Article by the Jakarta Post
http://www.thejakartapost.com/news/2009/10/08/blast-may-be-result-falling-space-waste-or-meteorite-lapan.html
To learn more on what has been learned so far, and to learn about NASA’s Asteroid Watch program and NASA’s Near-Earth Object Program, check out these links:
NEO Program October 19 Press Release
http://neo.jpl.nasa.gov/news/news165.html
Twitter Page for NASA’s Asteroid Watch
http://twitter.com/asteroidwatch
NASA’s Asteroid Watch
http://www.jpl.nasa.gov/asteroidwatch
NASA’s Near-Earth Object Program
http://www.jpl.nasa.gov/asteroidwatch
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Back on Thursday, October 8, around 11 am local time, the people of the coastal town of Bone on the island of Sulewesi, Indonesia, were frightened by thunderous sounds and shaking walls. The people rushed out of their homes, thinking they were in the middle of yet another earthquake. They were met by the sight of a twisting trail of debris in the sky. What they had experienced was in fact the result of an exploding fireball, which is called a bolide.
The bolide was caused by an asteroid with an estimated width of about 10 meters (33 feet). Atmospheric pressure caused it to explode, releasing an amount of energy equivalent to a small atomic bomb. The explosion triggered infrasound sensors of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) more than 10,000 km away. Analysis of the infrasound data revealed an explosion at latitude 4.5˚ S, longitude 120˚ E, close to Bone, with a yield of about 50 kilotons (100,000 pounds) of TNT, about two or three times the power of World War II-era atomic bombs.
The asteroid that caused the blast was not known to astronomers before the event. According to statistical studies of the near-Earth asteroid population, such objects are expected to collide with Earth on average every 2 to 12 years.
Those are just the barest of details, but I thought I would share. To get first-hand information on this event, check out these links:
YouTube Video of Local News Broadcast
http://www.youtube.com/watch?v=yeQBzTkJNhs&videos=jkRJgbXY-90
October 8th Article by the Jakarta Globe
http://thejakartaglobe.com/home/mysterious-explosion-panics-locals-in-south-sulawesi-police-still-investigating/334246
October 8th Article by the Jakarta Post
http://www.thejakartapost.com/news/2009/10/08/blast-may-be-result-falling-space-waste-or-meteorite-lapan.html
To learn more on what has been learned so far, and to learn about NASA’s Asteroid Watch program and NASA’s Near-Earth Object Program, check out these links:
NEO Program October 19 Press Release
http://neo.jpl.nasa.gov/news/news165.html
Twitter Page for NASA’s Asteroid Watch
http://twitter.com/asteroidwatch
NASA’s Asteroid Watch
http://www.jpl.nasa.gov/asteroidwatch
NASA’s Near-Earth Object Program
http://www.jpl.nasa.gov/asteroidwatch
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Wednesday, October 28, 2009
The Debate Over Pluto Continues
Science writer Alan Boyle will soon publish a book in which he outlines his objections to the 2006 ruling by the International Astronomical Union (IAU) that caused Pluto be classified as a dwarf planet rather than a planet. His new book is called, “The Case for Pluto: How a Little Planet Made a Big Difference,” available November 9.
The Case for Pluto: How a Little Planet Made a Big Difference
http://astore.amazon.com/roamingastron-20/detail/0470505443
The focus of Boyles dispute is the IAU's addition to the planetary definition that a planet must have cleared the neighborhood of its orbit. The addition demoted Pluto to a new class of celestial bodies known as dwarf planets. By the IAU definition, a dwarf planet orbits the Sun, is large enough that its gravity has crushed it into a sphere, but it has not cleared debris from its planetary neighborhood.
In his book, Boyle claims the IAU’s definition is too narrow and he suggests that even Earth might not be considered a planet by the IAU's definition because it too hasn't completely cleared its orbit.
Other astronomers also make the argument that the decision on Pluto comes too soon. They note that technology is only just beginning to allow the discovery of planets the size of Earth and smaller around other stars. And some astronomers believe there's still a possibility of finding objects bigger than Mercury in our own solar system.
Boyle cites the example of the "Captain Kirk rule," offered by Principal Investigator Alan Stern of NASA’s New Horizons mission to Pluto and the Kuiper belt. Stern’s rule states that if you are looking out the window of your spaceship, you’d like to know whether something is a planet just by looking at it.
When Clyde Tombaugh discovered Pluto at Lowell Observatory in 1930, it was thought to be the Planet X that astronomers had expected to find beyond the orbit of Neptune. But in the decades that followed, astronomers hypothesized that Pluto might be just the first of a number of objects beyond Neptune.
Astronomers reasoned these objects would be planetary leftovers from the early formation of the solar system and that they could exist in abundance in a region of the outer solar system we now know as the Kuiper belt (Kuiper rhymes with “viper”). The Kuiper belt, sometimes called the Edgeworth-Kuiper belt, was discovered in 1992 and named in honor of the work done by Irish astronomer Kenneth Edgeworth (1880 – 1972) and Dutch astronomer Gerard Kuiper (1905 – 1973). In contrast to Bolye and his contingency, other astronomers argue that if Pluto was discovered today, it would be classified as a Kuiper Belt Object.
Jupiter’s gravity kept the region of rocky debris known as the Asteroid Belt from forming into a planet. In that same way, Neptune's gravity has kept the icy objects of the Kuiper Belt from combining into a large planet as well.
For over fifty years, Pluto was the only object of its type to be found. Even Boyle admits that Tombaugh was lucky in finding it. The second Kuiper Belt Object (KBO) wasn't found until the 1990s, but that discovery was followed by a rash of other new KBOs. In 2005, Astronomer Mike Brown discovered an object beyond Neptune even larger than Pluto, and the IAU was compelled to vote on a new official planetary definition rather than face the possibility of having the outer solar system full of new planets.
To learn more about Pluto and the Kuiper Belt, and to learn more about Boyles new book, check out these links:
The Case for Pluto: How a Little Planet Made a Big Difference. Author Alan Boyle
http://astore.amazon.com/roamingastron-20/detail/0470505443
NASA’s New Horizons Mission to Pluto and the Kuiper Belt, Mission Home Page
http://pluto.jhuapl.edu/
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Science writer Alan Boyle will soon publish a book in which he outlines his objections to the 2006 ruling by the International Astronomical Union (IAU) that caused Pluto be classified as a dwarf planet rather than a planet. His new book is called, “The Case for Pluto: How a Little Planet Made a Big Difference,” available November 9.
The Case for Pluto: How a Little Planet Made a Big Difference
http://astore.amazon.com/roamingastron-20/detail/0470505443
The focus of Boyles dispute is the IAU's addition to the planetary definition that a planet must have cleared the neighborhood of its orbit. The addition demoted Pluto to a new class of celestial bodies known as dwarf planets. By the IAU definition, a dwarf planet orbits the Sun, is large enough that its gravity has crushed it into a sphere, but it has not cleared debris from its planetary neighborhood.
In his book, Boyle claims the IAU’s definition is too narrow and he suggests that even Earth might not be considered a planet by the IAU's definition because it too hasn't completely cleared its orbit.
Other astronomers also make the argument that the decision on Pluto comes too soon. They note that technology is only just beginning to allow the discovery of planets the size of Earth and smaller around other stars. And some astronomers believe there's still a possibility of finding objects bigger than Mercury in our own solar system.
Boyle cites the example of the "Captain Kirk rule," offered by Principal Investigator Alan Stern of NASA’s New Horizons mission to Pluto and the Kuiper belt. Stern’s rule states that if you are looking out the window of your spaceship, you’d like to know whether something is a planet just by looking at it.
When Clyde Tombaugh discovered Pluto at Lowell Observatory in 1930, it was thought to be the Planet X that astronomers had expected to find beyond the orbit of Neptune. But in the decades that followed, astronomers hypothesized that Pluto might be just the first of a number of objects beyond Neptune.
Astronomers reasoned these objects would be planetary leftovers from the early formation of the solar system and that they could exist in abundance in a region of the outer solar system we now know as the Kuiper belt (Kuiper rhymes with “viper”). The Kuiper belt, sometimes called the Edgeworth-Kuiper belt, was discovered in 1992 and named in honor of the work done by Irish astronomer Kenneth Edgeworth (1880 – 1972) and Dutch astronomer Gerard Kuiper (1905 – 1973). In contrast to Bolye and his contingency, other astronomers argue that if Pluto was discovered today, it would be classified as a Kuiper Belt Object.
Jupiter’s gravity kept the region of rocky debris known as the Asteroid Belt from forming into a planet. In that same way, Neptune's gravity has kept the icy objects of the Kuiper Belt from combining into a large planet as well.
For over fifty years, Pluto was the only object of its type to be found. Even Boyle admits that Tombaugh was lucky in finding it. The second Kuiper Belt Object (KBO) wasn't found until the 1990s, but that discovery was followed by a rash of other new KBOs. In 2005, Astronomer Mike Brown discovered an object beyond Neptune even larger than Pluto, and the IAU was compelled to vote on a new official planetary definition rather than face the possibility of having the outer solar system full of new planets.
To learn more about Pluto and the Kuiper Belt, and to learn more about Boyles new book, check out these links:
The Case for Pluto: How a Little Planet Made a Big Difference. Author Alan Boyle
http://astore.amazon.com/roamingastron-20/detail/0470505443
NASA’s New Horizons Mission to Pluto and the Kuiper Belt, Mission Home Page
http://pluto.jhuapl.edu/
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Tuesday, October 27, 2009
The Number of Sunspots is Growing
The Sun is beginning to show more signs of life. Sunspot 1029 came into our view over the weekend, and is just bristling with B- and C-class solar flares. The sunspot’s magnetic polarity indicate that it is part of new Solar Cycle 24. If it continues to grow at its current rate, this sunspot could soon become the biggest of 2009.
If you notice the size references at the bottom of the image, you will see that sunspot 1029 is already larger than the width of several Earths, and may be larger than the width of Jupiter before it is done. To learn more about the current sunspot activity, check out these links.
NASA/ESA’s Solar and Helospheric Observatory (SOHO)
http://sohowww.nascom.nasa.gov/
NASA/ESA’s SOHO Sunspot Page
http://sohowww.nascom.nasa.gov/sunspots/
While we are on the subject of the Sun, I should mention that there are a lot of solar missions currently flying, with more expected in the next few years. Here is a rundown of the most notable missions in progress.
NASA/ESA’s Solar and Heliospheric Observatory (SOHO)
Launched December 2, 1995, this international mission has been keeping a steady watch on the Sun. The SOHO team has been able to warn Earth of approaching coronal mass ejections that could potentially disrupt communications. Through the work of professionals and amateurs, SOHO has discovered dozens of comets, many of which are destroyed by the Sun’s powerful gravity and energy.
http://sohowww.nascom.nasa.gov/
NASA’s Advanced Composition Explorer (ACE)
Launched August 25, 1997, ACE measures particles that travel to Earth from the Sun, interplanetary space and the far reaches of the Milky Way.
http://www.srl.caltech.edu/ACE/
NASA’s Transition Region and Coronal Explorer (TRACE)
Launched April 2 ,1998, TRACE studies the three-dimensional magnetic structures which emerge through the Sun’s photosphere (the visible surface of the Sun) and defines both the geometry and dynamics of the upper solar atmosphere (the transition regioun and corona).
http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1998-020A
NASA’s ACRIM Sat
Launched December 20, 1999, ACRIMSat is the third in a series of long-term solar-monitoring satellites. The spacecraft tracks the impact of Total Solar Irradiance (TSI) on Earth's climate.
http://acrim.jpl.nasa.gov/
NASA’s Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)
Launched February 5, 2002, RHEESI uses X-ray imaging to explore the basic physics of particle acceleration and explosive energy release in solar flares -- gigantic explosions in the atmosphere of the Sun. RHESSI produced the first high-resolution movies of solar flares using their high-energy radiation. It also made the first images of a flare in gamma-rays, discovered strong polarization in a cosmic gamma-ray burst; and made the first hard X-ray imaging spectroscopy of flares from thermal to non-thermal energies. RHESSI also measured the roundness of the sun with unprecedented precision and found it is not a perfect sphere. The mission is named in honor of one of the founding mission members who died in 2001, Reuven Ramaty.
http://hesperia.gsfc.nasa.gov/hessi/index.html
Hinode (Solar-B)
Launched September 22, 2006, Hinode is an international mission to study the Sun. The spacecraft is designed to study the generation, transport and dissipation of magnetic energy from the photosphere to the corona and will record how energy stored in the sun's magnetic field is released. Hinode found the Sun's magnetic field is much more turbulent and dynamic than previously known. Spacecraft data showed magnetic waves play a critical role in driving the solar wind, a stream of electrically charged gas blasted away from the Sun. Better understanding of the solar wind may lead to more accurate prediction of damaging radiation waves before they reach satellites. The name Hinode is Japanese, meaning “sunrise.”
http://solarb.msfc.nasa.gov/
STEREO
Launched September 18, 2006, STEREO is actually two observatories. One moves ahead in Earth’s orbit and the other trails behind. These study the structure and evolution of solar storms as they blast from the Sun and move out through space. STEREO has made the first 3D measurements of a solar jet and is still sending information back to Earth from orbit.
http://stereo.gsfc.nasa.gov/
Interstellar Boundary Explorer (IBEX)
Launched October 19, 2008, IBEX is designed to detect the edge of our solar system. Operating from Earth orbit, the spacecraft uses neutral atom images to detect particles from the termination shock at the boundary between our solar system and interstellar space. IBEX made the first all-sky maps of the heliosphere. One of the immediate results was a surprise: the maps are bisected by a bright, winding ribbon of unknown origin. The finding could change our understanding of the heliosphere.
http://www.ibex.swri.edu/
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The Sun is beginning to show more signs of life. Sunspot 1029 came into our view over the weekend, and is just bristling with B- and C-class solar flares. The sunspot’s magnetic polarity indicate that it is part of new Solar Cycle 24. If it continues to grow at its current rate, this sunspot could soon become the biggest of 2009.
SOHO image of sunspot 1029. Image Credit: NASA
If you notice the size references at the bottom of the image, you will see that sunspot 1029 is already larger than the width of several Earths, and may be larger than the width of Jupiter before it is done. To learn more about the current sunspot activity, check out these links.
NASA/ESA’s Solar and Helospheric Observatory (SOHO)
http://sohowww.nascom.nasa.gov/
NASA/ESA’s SOHO Sunspot Page
http://sohowww.nascom.nasa.gov/sunspots/
While we are on the subject of the Sun, I should mention that there are a lot of solar missions currently flying, with more expected in the next few years. Here is a rundown of the most notable missions in progress.
NASA/ESA’s Solar and Heliospheric Observatory (SOHO)
Launched December 2, 1995, this international mission has been keeping a steady watch on the Sun. The SOHO team has been able to warn Earth of approaching coronal mass ejections that could potentially disrupt communications. Through the work of professionals and amateurs, SOHO has discovered dozens of comets, many of which are destroyed by the Sun’s powerful gravity and energy.
http://sohowww.nascom.nasa.gov/
NASA’s Advanced Composition Explorer (ACE)
Launched August 25, 1997, ACE measures particles that travel to Earth from the Sun, interplanetary space and the far reaches of the Milky Way.
http://www.srl.caltech.edu/ACE/
NASA’s Transition Region and Coronal Explorer (TRACE)
Launched April 2 ,1998, TRACE studies the three-dimensional magnetic structures which emerge through the Sun’s photosphere (the visible surface of the Sun) and defines both the geometry and dynamics of the upper solar atmosphere (the transition regioun and corona).
http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1998-020A
NASA’s ACRIM Sat
Launched December 20, 1999, ACRIMSat is the third in a series of long-term solar-monitoring satellites. The spacecraft tracks the impact of Total Solar Irradiance (TSI) on Earth's climate.
http://acrim.jpl.nasa.gov/
NASA’s Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)
Launched February 5, 2002, RHEESI uses X-ray imaging to explore the basic physics of particle acceleration and explosive energy release in solar flares -- gigantic explosions in the atmosphere of the Sun. RHESSI produced the first high-resolution movies of solar flares using their high-energy radiation. It also made the first images of a flare in gamma-rays, discovered strong polarization in a cosmic gamma-ray burst; and made the first hard X-ray imaging spectroscopy of flares from thermal to non-thermal energies. RHESSI also measured the roundness of the sun with unprecedented precision and found it is not a perfect sphere. The mission is named in honor of one of the founding mission members who died in 2001, Reuven Ramaty.
http://hesperia.gsfc.nasa.gov/hessi/index.html
Hinode (Solar-B)
Launched September 22, 2006, Hinode is an international mission to study the Sun. The spacecraft is designed to study the generation, transport and dissipation of magnetic energy from the photosphere to the corona and will record how energy stored in the sun's magnetic field is released. Hinode found the Sun's magnetic field is much more turbulent and dynamic than previously known. Spacecraft data showed magnetic waves play a critical role in driving the solar wind, a stream of electrically charged gas blasted away from the Sun. Better understanding of the solar wind may lead to more accurate prediction of damaging radiation waves before they reach satellites. The name Hinode is Japanese, meaning “sunrise.”
http://solarb.msfc.nasa.gov/
STEREO
Launched September 18, 2006, STEREO is actually two observatories. One moves ahead in Earth’s orbit and the other trails behind. These study the structure and evolution of solar storms as they blast from the Sun and move out through space. STEREO has made the first 3D measurements of a solar jet and is still sending information back to Earth from orbit.
http://stereo.gsfc.nasa.gov/
Interstellar Boundary Explorer (IBEX)
Launched October 19, 2008, IBEX is designed to detect the edge of our solar system. Operating from Earth orbit, the spacecraft uses neutral atom images to detect particles from the termination shock at the boundary between our solar system and interstellar space. IBEX made the first all-sky maps of the heliosphere. One of the immediate results was a surprise: the maps are bisected by a bright, winding ribbon of unknown origin. The finding could change our understanding of the heliosphere.
http://www.ibex.swri.edu/
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Monday, October 26, 2009
Astronomy is for Everyone, Part Three
In this installment we consider what many typically think about first when considering amateur astronomy--choosing a telescope.
Telescopes
At some point in their observing, every amateur astronomer considers whether a telescope can aide them in their observing. The light-gathering and magnifying power of telescopes brings out details of the Moon's surface. It reveals Jupiter's larger satellites and its banded clouds, as well as markings on Mars and the rings of Saturn.
There are three popular types of telescope configurations:
1. Refractors, which use lenses to collect and focus light.
2. Reflectors, which collect light with a large mirror.
3. Catadioptrics, which are a special class of telescope that use lenses as well as mirrors. They are considered by some as modified reflectors.
Refractor Telescopes
The familiar long tube telescope, with the lens in front and the eyepiece in back, is the standard design of the refractor telescope. This design is commonly seen in department stores. While all look generally the same in advertisements, quality varies tremendously.
Beware of advertising claims of extremely high magnification. These are usually achieved by pushing the telescope to its limit, and then the images are not satisfactory.
Look for sturdy mechanical construction. A spindly mount will wobble at the slightest touch and ruin the view. Favor models with low to medium power eyepieces of good quality, rather than those with high-power, low quality eyepieces. Fittings for the eyepieces, diagonal prism, and accessories should be of machined metal, not molded plastic.
Newtonian Reflector Telescopes
The Newtonian reflector (invented by Sir Isaac Newton) is a very popular and economical telescope. Its simple high performance design provides tremendous light grasp at the lowest cost per unit of aperture of any type of telescope. Many observatory telescopes are Newtonian designs. Small Newtonians are very portable because the tube can detach from the mount.
Because the light is gathered and bent by mirrors, the image is rotated and usually appears upside-down or sideways. Their large aperture makes them ideal for deep-space views of galaxies, star clusters, and nebulae. The optical design results in sharp, high-contrast planetary and lunar views.
Compound "Catadioptric" Telescopes
Compound telescopes combine the best features of refractors and reflectors into very compact, lightweight instruments. They use both mirrors and lenses, resulting in telescopes only about twice as long as they are wide. Unlike the basic refractor and reflector, these telescopes are distinctly modern 20th century designs, the products of high-technology manufacturing techniques.
The features are many -- the closed tube, lightweight, rugged designs are easily portable, and the superb optical performance is better in nearly every respect than any single telescope. Little if any maintenance or alignment is required. The lightweight optical assembly allows very strong mounts to be made very light in weight. Camera adapters and many varied accessories are widely available and easily attached. The one significant disadvantage is just what might be expected: compound telescopes cost more than other types of telescopes.
Maksutov-Cassegrain Telescopes
The Maksutov-Cassegrain telescope was introduced by D. D. Maksutov in 1944. It uses a deeply curved, thick front corrector lens, with a reflective spot on the corrector acting as a secondary mirror. Large diameter models are very difficult to manufacture and take a long time to reach thermal stability at night.
Schmidt-Cassegrain Telescopes
The Schmidt-Cassegrain design was made commercially economical due to the optical production innovations of Tom Johnson at Celestron International in the late 1960's. His techniques for producing the complex-curved Schmidt corrector plate were the foundation for every major manufacturer in the business.
Unlike the Maksutov, the Schmidt-Cassegrain has a separate, adjustable secondary mirror mechanically attached to the glass corrector plate. The most popular sizes are 8" to 11" diameter models on fork mounts. As with Maksutovs, large diameter models take a long time to reach thermal stability at night.
In our next installment we will examine telescope mounts...
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In this installment we consider what many typically think about first when considering amateur astronomy--choosing a telescope.
Telescopes
At some point in their observing, every amateur astronomer considers whether a telescope can aide them in their observing. The light-gathering and magnifying power of telescopes brings out details of the Moon's surface. It reveals Jupiter's larger satellites and its banded clouds, as well as markings on Mars and the rings of Saturn.
There are three popular types of telescope configurations:
1. Refractors, which use lenses to collect and focus light.
2. Reflectors, which collect light with a large mirror.
3. Catadioptrics, which are a special class of telescope that use lenses as well as mirrors. They are considered by some as modified reflectors.
Refractor Telescopes
The familiar long tube telescope, with the lens in front and the eyepiece in back, is the standard design of the refractor telescope. This design is commonly seen in department stores. While all look generally the same in advertisements, quality varies tremendously.
Beware of advertising claims of extremely high magnification. These are usually achieved by pushing the telescope to its limit, and then the images are not satisfactory.
Look for sturdy mechanical construction. A spindly mount will wobble at the slightest touch and ruin the view. Favor models with low to medium power eyepieces of good quality, rather than those with high-power, low quality eyepieces. Fittings for the eyepieces, diagonal prism, and accessories should be of machined metal, not molded plastic.
Newtonian Reflector Telescopes
The Newtonian reflector (invented by Sir Isaac Newton) is a very popular and economical telescope. Its simple high performance design provides tremendous light grasp at the lowest cost per unit of aperture of any type of telescope. Many observatory telescopes are Newtonian designs. Small Newtonians are very portable because the tube can detach from the mount.
Because the light is gathered and bent by mirrors, the image is rotated and usually appears upside-down or sideways. Their large aperture makes them ideal for deep-space views of galaxies, star clusters, and nebulae. The optical design results in sharp, high-contrast planetary and lunar views.
Compound "Catadioptric" Telescopes
Compound telescopes combine the best features of refractors and reflectors into very compact, lightweight instruments. They use both mirrors and lenses, resulting in telescopes only about twice as long as they are wide. Unlike the basic refractor and reflector, these telescopes are distinctly modern 20th century designs, the products of high-technology manufacturing techniques.
The features are many -- the closed tube, lightweight, rugged designs are easily portable, and the superb optical performance is better in nearly every respect than any single telescope. Little if any maintenance or alignment is required. The lightweight optical assembly allows very strong mounts to be made very light in weight. Camera adapters and many varied accessories are widely available and easily attached. The one significant disadvantage is just what might be expected: compound telescopes cost more than other types of telescopes.
Maksutov-Cassegrain Telescopes
The Maksutov-Cassegrain telescope was introduced by D. D. Maksutov in 1944. It uses a deeply curved, thick front corrector lens, with a reflective spot on the corrector acting as a secondary mirror. Large diameter models are very difficult to manufacture and take a long time to reach thermal stability at night.
Schmidt-Cassegrain Telescopes
The Schmidt-Cassegrain design was made commercially economical due to the optical production innovations of Tom Johnson at Celestron International in the late 1960's. His techniques for producing the complex-curved Schmidt corrector plate were the foundation for every major manufacturer in the business.
Unlike the Maksutov, the Schmidt-Cassegrain has a separate, adjustable secondary mirror mechanically attached to the glass corrector plate. The most popular sizes are 8" to 11" diameter models on fork mounts. As with Maksutovs, large diameter models take a long time to reach thermal stability at night.
In our next installment we will examine telescope mounts...
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Sunday, October 25, 2009
Jesus Brought God's Grace
(Luke 4:16-22)
Today, Nazareth is the capital and the largest city in the Northern District of Israel, having a population of about 185,000. In Jesus’ time, Nazareth was a village in lower Galilee. People of that time often looked down upon the village and its inhabitants. This attitude may have been caused by Nazareth’s small size, unpolished dialect of the inhabitants, a general lack of culture or significance, and perhaps even questionable moral and religious respectability. Even so, it soon became a place of significance because Jesus grew up there.
Jesus went to the synagogue in Nazareth on the Sabbath, as was His custom for so many years. Jesus must have been respected in the synagogue and must have been asked on several occasions to read from Scripture and comment on it. Jesus stood to read the Scriptures. Jesus was given the scroll of the prophet Isaiah. We do not know if Jesus asked for this particular scroll, but we do know that Jesus was given the scroll of the prophet Isaiah. Jesus chose a particular place in the scroll from which to read. We know this Scripture passage as Isaiah 61:1-2. Jesus used this passage to emphasize His identification with the subject of Isaiah’s writing—the Messiah.
The Spirit of the Lord is on me,
because he has anointed me
to preach good news to the poor.
He has sent me to proclaim freedom for the prisoners
and recovery of sight for the blind,
to release the oppressed,
to proclaim the year of the Lord's favor.
--Luke 4:18-19 NIV
This Scripture passage gives the purpose for Jesus’ coming. The passage that Jesus read in the synagogue announces that the Spirit of the Lord is upon the Christ, the One anointed by God. Anointing means to set aside for some unique and special purposes. Jesus had come to proclaim God’s good news and to heal broken lives.
Luke tells us that after reading, Jesus rolled up the scroll, returned it, and sat down. Sitting indicated that Jesus would discuss and explain what He had read. As everyone listened Jesus told them that God’s Word, spoken long ago by Isaiah, had been fulfilled as they were listening. The long wait was over.
The people complemented Jesus on his reading and they were amazed as they listened to His comments, which Luke characterizes as words of grace.
Even so, the people wondered at what they heard. They asked each other, “Isn’t this Joseph’s son?” They had watched this one grow from a little boy into a man. But He was more than that. He was Jesus, Son of god, who brought God’s grace into the world.
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(Luke 4:16-22)
Today, Nazareth is the capital and the largest city in the Northern District of Israel, having a population of about 185,000. In Jesus’ time, Nazareth was a village in lower Galilee. People of that time often looked down upon the village and its inhabitants. This attitude may have been caused by Nazareth’s small size, unpolished dialect of the inhabitants, a general lack of culture or significance, and perhaps even questionable moral and religious respectability. Even so, it soon became a place of significance because Jesus grew up there.
Jesus went to the synagogue in Nazareth on the Sabbath, as was His custom for so many years. Jesus must have been respected in the synagogue and must have been asked on several occasions to read from Scripture and comment on it. Jesus stood to read the Scriptures. Jesus was given the scroll of the prophet Isaiah. We do not know if Jesus asked for this particular scroll, but we do know that Jesus was given the scroll of the prophet Isaiah. Jesus chose a particular place in the scroll from which to read. We know this Scripture passage as Isaiah 61:1-2. Jesus used this passage to emphasize His identification with the subject of Isaiah’s writing—the Messiah.
The Spirit of the Lord is on me,
because he has anointed me
to preach good news to the poor.
He has sent me to proclaim freedom for the prisoners
and recovery of sight for the blind,
to release the oppressed,
to proclaim the year of the Lord's favor.
--Luke 4:18-19 NIV
This Scripture passage gives the purpose for Jesus’ coming. The passage that Jesus read in the synagogue announces that the Spirit of the Lord is upon the Christ, the One anointed by God. Anointing means to set aside for some unique and special purposes. Jesus had come to proclaim God’s good news and to heal broken lives.
Luke tells us that after reading, Jesus rolled up the scroll, returned it, and sat down. Sitting indicated that Jesus would discuss and explain what He had read. As everyone listened Jesus told them that God’s Word, spoken long ago by Isaiah, had been fulfilled as they were listening. The long wait was over.
The people complemented Jesus on his reading and they were amazed as they listened to His comments, which Luke characterizes as words of grace.
Even so, the people wondered at what they heard. They asked each other, “Isn’t this Joseph’s son?” They had watched this one grow from a little boy into a man. But He was more than that. He was Jesus, Son of god, who brought God’s grace into the world.
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Saturday, October 24, 2009
Astronomy is for Everyone, Part Two
Today we have the second installment of our tips for getting started right in amateur astronomy.
Binoculars
Every observer should own a good pair of binoculars. These gather far more light than the eye, they magnify images and use the capacity of both eyes. Binoculars are the ideal instrument for the beginning observer for the following reasons:
1. They are portable.
2. They have a wide field of view.
3. They are relatively inexpensive.
4. They will still be of use even if you later progress to a telescope.
Binoculars are ideal for helping the beginner find their way around the night sky. Star colors are more noticeable through them.
Binoculars are well suited for:
* Scanning star clusters
* Picking out nebulae and galaxies
* Recording light changes in variable stars
* Watching for novae and comets
* Observing Jupiter and its 4 main moons
* Observing Mercury in twilight
* Observing the crescent of Venus
* Searching for dim Uranus and Neptune
* Observing bright asteroids
* Getting to know our closest neighbor, the Moon
Choosing Binoculars
The beginning observer might be tempted to think that bigger is better. However, when choosing binoculars, a pair with a magnification of 7 to 10 times is advisable because of the
increased weight. Anything larger would be difficult to steady by hand.
Consider this progression before choosing high magnification binoculars.
1. Higher magnification
2. Heavier binoculars
3. More difficult to steady
4. Bigger images with bigger and more frequent shakes
5. Unhappy observing
High magnification binoculars are used by many experienced observers, but they are normally mounted in order to provide the steadiest images possible.
Binoculars require prisms in order to give the observer a right side up image. Porro prism binoculars are the most common type. Binoculars of the roof prism design are also very good and they also have the added feature of compactness.
Many stores have seasonal sales on binoculars. This makes it possible to own a good pair of binoculars on even a tight budget. Before buying, you should try them out first to make sure that the images appear sharp and clear. If you cannot find a good brick-and-mortar store where you can pick up the exact pair of binoculars you are considering, make sure that the online store you use has a no-questions-asked policy on returns.
Unwrap the binoculars and focus them on a point of light as far away as possible and check for flaws in the image. If you see any distortion in the light, that will only be intensified when you are gazing at a sky full of pinpoint light sources! Don't let someone else pick out a pair for you because their eyes might not see an image exactly the way yours do. Another important point when examining binoculars is to check for the presence and amount of coatings on the optics. A good pair of binoculars will have anti-reflective coatings on each surface of every lens and prism in the binoculars. This reduces the possibility of glare and reflected images when observing. Beware of manufacturer packaging. While all say they use coated optics, not all use only completely coated optics.
Stay tuned for the next installment, telescopes...
Today we have the second installment of our tips for getting started right in amateur astronomy.
Binoculars
Every observer should own a good pair of binoculars. These gather far more light than the eye, they magnify images and use the capacity of both eyes. Binoculars are the ideal instrument for the beginning observer for the following reasons:
1. They are portable.
2. They have a wide field of view.
3. They are relatively inexpensive.
4. They will still be of use even if you later progress to a telescope.
Binoculars are ideal for helping the beginner find their way around the night sky. Star colors are more noticeable through them.
Binoculars are well suited for:
* Scanning star clusters
* Picking out nebulae and galaxies
* Recording light changes in variable stars
* Watching for novae and comets
* Observing Jupiter and its 4 main moons
* Observing Mercury in twilight
* Observing the crescent of Venus
* Searching for dim Uranus and Neptune
* Observing bright asteroids
* Getting to know our closest neighbor, the Moon
Choosing Binoculars
The beginning observer might be tempted to think that bigger is better. However, when choosing binoculars, a pair with a magnification of 7 to 10 times is advisable because of the
increased weight. Anything larger would be difficult to steady by hand.
Consider this progression before choosing high magnification binoculars.
1. Higher magnification
2. Heavier binoculars
3. More difficult to steady
4. Bigger images with bigger and more frequent shakes
5. Unhappy observing
High magnification binoculars are used by many experienced observers, but they are normally mounted in order to provide the steadiest images possible.
Binoculars require prisms in order to give the observer a right side up image. Porro prism binoculars are the most common type. Binoculars of the roof prism design are also very good and they also have the added feature of compactness.
Many stores have seasonal sales on binoculars. This makes it possible to own a good pair of binoculars on even a tight budget. Before buying, you should try them out first to make sure that the images appear sharp and clear. If you cannot find a good brick-and-mortar store where you can pick up the exact pair of binoculars you are considering, make sure that the online store you use has a no-questions-asked policy on returns.
Unwrap the binoculars and focus them on a point of light as far away as possible and check for flaws in the image. If you see any distortion in the light, that will only be intensified when you are gazing at a sky full of pinpoint light sources! Don't let someone else pick out a pair for you because their eyes might not see an image exactly the way yours do. Another important point when examining binoculars is to check for the presence and amount of coatings on the optics. A good pair of binoculars will have anti-reflective coatings on each surface of every lens and prism in the binoculars. This reduces the possibility of glare and reflected images when observing. Beware of manufacturer packaging. While all say they use coated optics, not all use only completely coated optics.
Stay tuned for the next installment, telescopes...
Friday, October 23, 2009
First Results of SPT’s SZ Survey
On Saturday, October 10, the astronomy team managing the South Pole Telescope released the first results from their initial SZ survey. Wait. You didn’t know we had a telescope at the South Pole? It’s true. We do.
The SPT is a colaborative effort, supported by many U.S. universities and organizations, including the Jet Propulsion Laboratory (JPL), with most of the staff based at the University of Chicago. Located at the Amundsen-Scott South Pole Station, the SPT was constructed between November 2006 and February 2007, and saw first light on February 16.
The largest telescope deployed at the South Pole, the SPT stands 22.8 meters tall and has a 10-meter dish covered with a network of detectors. Like a few other cutting-edge programs, including the ESA/NASA Planck mission, SPT is studying cosmic microwave background radiation (CMBR), the afterglow of the Big Bang. On the electromagnetic spectrum, CMBR falls somewhere between heat radiation and radio waves. The CMBR is mostly uniform, but it contains tiny ripples of varying density and temperature. These ripples reflect the seeds that, through gravitational attraction, grew into the galaxies and galaxy clusters that are visible today.
One advantage of the SPT location is the darkness. The months of darkness during the South Pole winter gives ample opportunities for exploring the skies, and the desolate location ensurse that light pollution from buildings and streetlamps is of little concern. Dry, cold air allows CMBR to be observed with minimal interference from water vapor.
Another advantage of the locating at the South Pole is that the observed celestial bodies do not set, but instead rotate once every 24 hours around celestial north. This allows the scientists to track on a point in the sky for months or even years. This is in contrast to the middle latitudes where stars eventualy dip below the horizon after a few hours.
The SPT is currently conducting a Sunyaev-Zel'dovich (SZ) effect survey over large areas of the southern sky, searching for massive galaxy clusters to high redshift. The SZ effect is the result of high energy electrons distorting the CMBR through a phenomenon called inverse Compton scatting. In their preliminary study, the team is focusing on a 40 square-degree area targeted by the Blanco Cosmology Survey (BCS). Over two seasons of observations, the region has been mapped by the SPT at frequencies of 95 GHz, 150 GHz, and 225 GHz.
On October 10, the team reported the four most significant detections of SZ-effected galaxy clusters in this field, three of which were previously unknown and, therefore, represent the first three galaxy clusters discovered with an SZ survey. The team is very excited about the latest results because they demostrate that SZ surveys can be an effective means of finding galaxy cluters. The results also show that the SPT is a very effective instrument for this type of study.
For more on the SPT and other CMBR-related missions, check out these links:
South Pole Telescope
http://pole.uchicago.edu/
Planck Mission, ESA Home Page
http://www.esa.int/planck
Planck Mission, NASA Home Page
http://www.nasa.gov/planck
NASA’s Legacy Archive for Microwave Background Data Analysis
http://lambda.gsfc.nasa.gov/
NASA's Cosmic Background Explorer (COBE) Archive Page
http://lambda.gsfc.nasa.gov/product/cobe/
NASA's Wilkinson Microwave Anisotropy Probe (WMAP) Archive Page
http://lambda.gsfc.nasa.gov/product/map/current/
NASA's and the Netherlands (NIVR) Infrared Astronomical Satellite (IRAS) Archive Page
http://lambda.gsfc.nasa.gov/product/iras/
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On Saturday, October 10, the astronomy team managing the South Pole Telescope released the first results from their initial SZ survey. Wait. You didn’t know we had a telescope at the South Pole? It’s true. We do.
The SPT is a colaborative effort, supported by many U.S. universities and organizations, including the Jet Propulsion Laboratory (JPL), with most of the staff based at the University of Chicago. Located at the Amundsen-Scott South Pole Station, the SPT was constructed between November 2006 and February 2007, and saw first light on February 16.
The largest telescope deployed at the South Pole, the SPT stands 22.8 meters tall and has a 10-meter dish covered with a network of detectors. Like a few other cutting-edge programs, including the ESA/NASA Planck mission, SPT is studying cosmic microwave background radiation (CMBR), the afterglow of the Big Bang. On the electromagnetic spectrum, CMBR falls somewhere between heat radiation and radio waves. The CMBR is mostly uniform, but it contains tiny ripples of varying density and temperature. These ripples reflect the seeds that, through gravitational attraction, grew into the galaxies and galaxy clusters that are visible today.
One advantage of the SPT location is the darkness. The months of darkness during the South Pole winter gives ample opportunities for exploring the skies, and the desolate location ensurse that light pollution from buildings and streetlamps is of little concern. Dry, cold air allows CMBR to be observed with minimal interference from water vapor.
Another advantage of the locating at the South Pole is that the observed celestial bodies do not set, but instead rotate once every 24 hours around celestial north. This allows the scientists to track on a point in the sky for months or even years. This is in contrast to the middle latitudes where stars eventualy dip below the horizon after a few hours.
The SPT is currently conducting a Sunyaev-Zel'dovich (SZ) effect survey over large areas of the southern sky, searching for massive galaxy clusters to high redshift. The SZ effect is the result of high energy electrons distorting the CMBR through a phenomenon called inverse Compton scatting. In their preliminary study, the team is focusing on a 40 square-degree area targeted by the Blanco Cosmology Survey (BCS). Over two seasons of observations, the region has been mapped by the SPT at frequencies of 95 GHz, 150 GHz, and 225 GHz.
On October 10, the team reported the four most significant detections of SZ-effected galaxy clusters in this field, three of which were previously unknown and, therefore, represent the first three galaxy clusters discovered with an SZ survey. The team is very excited about the latest results because they demostrate that SZ surveys can be an effective means of finding galaxy cluters. The results also show that the SPT is a very effective instrument for this type of study.
For more on the SPT and other CMBR-related missions, check out these links:
South Pole Telescope
http://pole.uchicago.edu/
Planck Mission, ESA Home Page
http://www.esa.int/planck
Planck Mission, NASA Home Page
http://www.nasa.gov/planck
NASA’s Legacy Archive for Microwave Background Data Analysis
http://lambda.gsfc.nasa.gov/
NASA's Cosmic Background Explorer (COBE) Archive Page
http://lambda.gsfc.nasa.gov/product/cobe/
NASA's Wilkinson Microwave Anisotropy Probe (WMAP) Archive Page
http://lambda.gsfc.nasa.gov/product/map/current/
NASA's and the Netherlands (NIVR) Infrared Astronomical Satellite (IRAS) Archive Page
http://lambda.gsfc.nasa.gov/product/iras/
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Thursday, October 22, 2009
Welcome the Galilean Nights
If you have wanted to see the wonders of the night sky and didn’t have a telescope, now is your chance! Just look around for an astronomy club, planetarium, science museum, or science center in your area. They are sure to be out and about over the next three evenings. From this Thursday evening through Saturday evening (October 22 through 24), amateur and professional astronomers have been asked to observe (pun intended) the “Galilean Nights,” a Cornerstone Project of the International Year of Astronomy 2009.
Promoted by the International Astronomical Union (IAU), the “Galilean Nights” is an international project encouraging amateur and professional astronomers, enthusiasts and the public, to head outside and point their telescopes toward the wonders of the night sky that were first observed 400 years ago by revolutionary Italian astronomer Galileo Galilei (1564 – 1642).
In a coordinated effort, astronomers will share their knowledge and enthusiasm for space by encouraging as many people as possible to look through a telescope at our planetary neighbors. The celestial bodies being emphasized are those that Galileo observed, including Jupiter and the Moon, which will be in good positions for observing.
The planners hope to give hundreds of thousands of people the thrill of looking through an astronomical telescope for the first time. More than 1,000 public events in over 70 countries are participating.
Galileo build his first two-lens telescope in mid-1609 based on the design of German-Dutch lensmaker Hans Lippershey, who constructed the first telescope in the Netherlands in 1608. Based upon available material, historians estimate that Galileo first his telescope toward the sky in October 1609. His observations eventually led him to discover many things. Galileo discovered the four main satellites of Jupiter. He realized that Earth’s moon was pitted with craters and not a perfect sphere. These and many other discoveries led Galileo to conclude, like polish astronomer Nicolaus Copernicus (1473 – 1543), that the Earth revolved around the Sun and not the other way around.
Galileo was tried for heresy by the Vatican and forced to recant. The last ten years of Galileo’s life were spent under house arrest. Thankfully, we today are not subject to the same restrictions of thought, so do something about it. Get out their and see the wonders of the nighttime sky. They are waiting just for you!
To find a “Galilean Nights” event in your area, to learn more about the “Galilean Nights” project, and to learn more about the International Year of Astronomy 2009, check out these links:
Galilean Nights
http://www.galileannights.org/
International Year of Astronomy 2009
http://www.astronomy2009.org/
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If you have wanted to see the wonders of the night sky and didn’t have a telescope, now is your chance! Just look around for an astronomy club, planetarium, science museum, or science center in your area. They are sure to be out and about over the next three evenings. From this Thursday evening through Saturday evening (October 22 through 24), amateur and professional astronomers have been asked to observe (pun intended) the “Galilean Nights,” a Cornerstone Project of the International Year of Astronomy 2009.
Promoted by the International Astronomical Union (IAU), the “Galilean Nights” is an international project encouraging amateur and professional astronomers, enthusiasts and the public, to head outside and point their telescopes toward the wonders of the night sky that were first observed 400 years ago by revolutionary Italian astronomer Galileo Galilei (1564 – 1642).
In a coordinated effort, astronomers will share their knowledge and enthusiasm for space by encouraging as many people as possible to look through a telescope at our planetary neighbors. The celestial bodies being emphasized are those that Galileo observed, including Jupiter and the Moon, which will be in good positions for observing.
The planners hope to give hundreds of thousands of people the thrill of looking through an astronomical telescope for the first time. More than 1,000 public events in over 70 countries are participating.
Galileo build his first two-lens telescope in mid-1609 based on the design of German-Dutch lensmaker Hans Lippershey, who constructed the first telescope in the Netherlands in 1608. Based upon available material, historians estimate that Galileo first his telescope toward the sky in October 1609. His observations eventually led him to discover many things. Galileo discovered the four main satellites of Jupiter. He realized that Earth’s moon was pitted with craters and not a perfect sphere. These and many other discoveries led Galileo to conclude, like polish astronomer Nicolaus Copernicus (1473 – 1543), that the Earth revolved around the Sun and not the other way around.
Galileo was tried for heresy by the Vatican and forced to recant. The last ten years of Galileo’s life were spent under house arrest. Thankfully, we today are not subject to the same restrictions of thought, so do something about it. Get out their and see the wonders of the nighttime sky. They are waiting just for you!
To find a “Galilean Nights” event in your area, to learn more about the “Galilean Nights” project, and to learn more about the International Year of Astronomy 2009, check out these links:
Galilean Nights
http://www.galileannights.org/
International Year of Astronomy 2009
http://www.astronomy2009.org/
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Wednesday, October 21, 2009
Ares I-X Prepares for Critical Test Flight
Early Tuesday, the Ares I-X rocket was slowly moved from the Vehicle Assembly Building to Launch Complex 39B at NASA's Kennedy Space Center, Florida. Launch is set for October 27 at 8 a.m. EDT. If rescheduling is necessary, other launch opportunities are available October 28 and 29.
The Ares I-X is a full-scale replica of the Ares I, a key element in NASA's Constellation program. The goals of Constellation are to (1) replace the soon-to-retire Space Shuttle orbiters with a safer, lower-cost rocket to carry astronauts to low-Earth orbit and (2) development of the Ares V, a large, unmanned heavy lift rocket that would support eventual expeditions to the moon.
While the 327-foot-tall Ares I-X is a replica, not all of its elements match the final Ares I design. The 1.8-million-pound Ares I-X rocket is composed of two stages. The first stage is a four-segment solid-fuel booster based on technology from the Space Shuttle program (the production Ares I will have five segments), the second stage is a dummy and perched atop is a mockup of an Orion crew capsule and escape rocket. More than 700 sensors have been mounted on the launch vehicle as well as three television cameras in order gather as much data as possible.
The goals of the test flight are to verify computer models and flight characteristics during the critical first two minutes of flight when aerodynamic stresses are most severe. When launched, the first stage will fire for two minutes, boosting the vehicle to an altitude of about 130,000 feet and a velocity of nearly five times the speed of sound. At that point, roughly 43 miles due east of the launch site, the first stage will separate and fall to the Atlantic Ocean, testing the new parachutes designed for the Ares I. The dummy upper stage will crash into the Atlantic about 147 miles from the launch site and will not be recovered.
The total cost of the Ares I-X project--including launch vehicle and all preparations and management--is expected to be around $445 million. This launch is a critical test flight, as it will likely play a major role in the ongoing debate about NASA's post-shuttle manned space program.
The White House is currently reassessing the program, considering five options that have been developed by an independent panel of space experts led by former Lockheed Martin CEO Norman Augustine. Only one of the five options includes the Ares I. The test flight of the Ares I-X could prove critical to the future of the Constellation program. A success would not guarantee a continuation of Constellation, but a failure could prove fatal.
To learn more about the Aries launch vehicles, the Orion spacecraft, or the Constellation program in general, check out these links:
NASA’s Constellation Program
http://www.nasa.gov/constellation/
NASA’s Ares I-X Launch Vehicle, part of the Constellation program site
http://www.nasa.gov/mission_pages/constellation/ares/flighttests/aresIx/index.html
NASA’s Ares Launch Vehicle Family, part of the Constellation program site
http://www.nasa.gov/ares/
NASA’s Orion Spacecraft, part of the Constellation program site
http://www.nasa.gov/orion/
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Early Tuesday, the Ares I-X rocket was slowly moved from the Vehicle Assembly Building to Launch Complex 39B at NASA's Kennedy Space Center, Florida. Launch is set for October 27 at 8 a.m. EDT. If rescheduling is necessary, other launch opportunities are available October 28 and 29.
The Ares I-X is a full-scale replica of the Ares I, a key element in NASA's Constellation program. The goals of Constellation are to (1) replace the soon-to-retire Space Shuttle orbiters with a safer, lower-cost rocket to carry astronauts to low-Earth orbit and (2) development of the Ares V, a large, unmanned heavy lift rocket that would support eventual expeditions to the moon.
While the 327-foot-tall Ares I-X is a replica, not all of its elements match the final Ares I design. The 1.8-million-pound Ares I-X rocket is composed of two stages. The first stage is a four-segment solid-fuel booster based on technology from the Space Shuttle program (the production Ares I will have five segments), the second stage is a dummy and perched atop is a mockup of an Orion crew capsule and escape rocket. More than 700 sensors have been mounted on the launch vehicle as well as three television cameras in order gather as much data as possible.
The goals of the test flight are to verify computer models and flight characteristics during the critical first two minutes of flight when aerodynamic stresses are most severe. When launched, the first stage will fire for two minutes, boosting the vehicle to an altitude of about 130,000 feet and a velocity of nearly five times the speed of sound. At that point, roughly 43 miles due east of the launch site, the first stage will separate and fall to the Atlantic Ocean, testing the new parachutes designed for the Ares I. The dummy upper stage will crash into the Atlantic about 147 miles from the launch site and will not be recovered.
The total cost of the Ares I-X project--including launch vehicle and all preparations and management--is expected to be around $445 million. This launch is a critical test flight, as it will likely play a major role in the ongoing debate about NASA's post-shuttle manned space program.
The White House is currently reassessing the program, considering five options that have been developed by an independent panel of space experts led by former Lockheed Martin CEO Norman Augustine. Only one of the five options includes the Ares I. The test flight of the Ares I-X could prove critical to the future of the Constellation program. A success would not guarantee a continuation of Constellation, but a failure could prove fatal.
To learn more about the Aries launch vehicles, the Orion spacecraft, or the Constellation program in general, check out these links:
NASA’s Constellation Program
http://www.nasa.gov/constellation/
NASA’s Ares I-X Launch Vehicle, part of the Constellation program site
http://www.nasa.gov/mission_pages/constellation/ares/flighttests/aresIx/index.html
NASA’s Ares Launch Vehicle Family, part of the Constellation program site
http://www.nasa.gov/ares/
NASA’s Orion Spacecraft, part of the Constellation program site
http://www.nasa.gov/orion/
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Tuesday, October 20, 2009
Thirty-Two More for HARPS
This week--October 19 through 23--in Porto, Portugal, the European Southern Observatory (ESO) is jointly holding an international conference with Centro de Astrofísica da Universidade do Porto (CAUP), a private astronomical association of the University of Porto. The topic of the conference is the progress of exoplanet studies--exoplanets being extrasolar planets, or planets orbiting in other star systems.
On Monday, those attending received a report on the first five years of operation of the High Accuracy Radial Velocity Planet Searcher (HARPS), the spectrograph used on ESO’s 3.6 meter telescope. The HARPS team was excited to announce that in its first five years of operation, HARPS had discovered 75 exoplanets in 30 different planetary systems. This number included the announcement of 32 brand new exoplanets discovered by HARPS.
The precision of HARPS has allowed astronomers to search for small planets, those with a mass of a few times that of the Earth--known as super-Earths and Neptune-like planets. To date, HARPS has discovered 24 of the 28 planets known to have masses below 20 Earth masses. Most of the new low-mass planets reside in multi-planet systems, with up to five planets per system.
First installed in 2003, HARPS is able to measure the back-and-forward motions of stars by detecting small changes in a star’s radial velocity--as small as 3.5 km/hour. This precision is crucial for the discovery of exoplanets and the radial velocity method, the most prolific method for searching for exoplanets. The radial velocity method is one which detects small changes in the radial velocity of a star as it wobbles slightly under the gentle gravitiational pull from an unseen orbiting planet.
The achievement of the HARPS observing teams has increased the number of known low-mass planets by 30 percent. As of this latest count, there are roughly 400 known exoplanets. To learn more about the discoveries of HARPS and about exoplanets in general, check out these links:
European Southern Observatory (ESO) October 19 News Release and Images
http://www.eso.org/public/outreach/press-rel/pr-2009/pr-39-09.html
European Southern Observatory (ESO)
http://www.eso.org/
Extrasolar Planets Encyclopaedia
http://exoplanet.eu/
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This week--October 19 through 23--in Porto, Portugal, the European Southern Observatory (ESO) is jointly holding an international conference with Centro de Astrofísica da Universidade do Porto (CAUP), a private astronomical association of the University of Porto. The topic of the conference is the progress of exoplanet studies--exoplanets being extrasolar planets, or planets orbiting in other star systems.
On Monday, those attending received a report on the first five years of operation of the High Accuracy Radial Velocity Planet Searcher (HARPS), the spectrograph used on ESO’s 3.6 meter telescope. The HARPS team was excited to announce that in its first five years of operation, HARPS had discovered 75 exoplanets in 30 different planetary systems. This number included the announcement of 32 brand new exoplanets discovered by HARPS.
The precision of HARPS has allowed astronomers to search for small planets, those with a mass of a few times that of the Earth--known as super-Earths and Neptune-like planets. To date, HARPS has discovered 24 of the 28 planets known to have masses below 20 Earth masses. Most of the new low-mass planets reside in multi-planet systems, with up to five planets per system.
First installed in 2003, HARPS is able to measure the back-and-forward motions of stars by detecting small changes in a star’s radial velocity--as small as 3.5 km/hour. This precision is crucial for the discovery of exoplanets and the radial velocity method, the most prolific method for searching for exoplanets. The radial velocity method is one which detects small changes in the radial velocity of a star as it wobbles slightly under the gentle gravitiational pull from an unseen orbiting planet.
The achievement of the HARPS observing teams has increased the number of known low-mass planets by 30 percent. As of this latest count, there are roughly 400 known exoplanets. To learn more about the discoveries of HARPS and about exoplanets in general, check out these links:
European Southern Observatory (ESO) October 19 News Release and Images
http://www.eso.org/public/outreach/press-rel/pr-2009/pr-39-09.html
European Southern Observatory (ESO)
http://www.eso.org/
Extrasolar Planets Encyclopaedia
http://exoplanet.eu/
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Monday, October 19, 2009
LCROSS Confirmation of Impact Plume
In Friday, October 16, the mission teams for NASA’s Lunar CRater Observation and Sensing Satellite (LCROSS) released images covering all phases of the first impact on Friday, October 9. The teams appear to be ecstatic about the quality of the data they are now working with.
The announcement on Friday included the release of several images of the impact plume created by the Centaur upper stage. The images are in visible light and infrared. The plume appeared to measure 6 to 8 kilometers across, as detected by the LCROSS instruments from 600 kilometers above the impact. The data clearly indicates a plume of vapor and fine debris. The brightness of the ejected material appears to be at the low end of the team’s predictions and may provide a clue to the properties of the material that was struck.
VisibleCamera image of the Centaur impact plume from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394553main_Visible-Camera-impact-plume.png
Zoomed-in VisibleCamera image of the Centaur impact plume from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394555main_Visible-Camera-impact-plume-zoom.png
Mid-Infrared Camera Images of Centaur Impact from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394506main_MIR-camera-images-1_full.png
Near-Infrared Camera Image from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394522main_NIR-camera-image-1_full.png
Centaur Impact Images from NASA’s LCROSS Spacecraft
http://www.nasa.gov/mission_pages/LCROSS/main/LCROSS_impact_images.html
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In Friday, October 16, the mission teams for NASA’s Lunar CRater Observation and Sensing Satellite (LCROSS) released images covering all phases of the first impact on Friday, October 9. The teams appear to be ecstatic about the quality of the data they are now working with.
The announcement on Friday included the release of several images of the impact plume created by the Centaur upper stage. The images are in visible light and infrared. The plume appeared to measure 6 to 8 kilometers across, as detected by the LCROSS instruments from 600 kilometers above the impact. The data clearly indicates a plume of vapor and fine debris. The brightness of the ejected material appears to be at the low end of the team’s predictions and may provide a clue to the properties of the material that was struck.
LCROSS image taken from 600 km above the surface, taken fifteen seconds after the Centaur upper stage hit the floor of crater Cabeus. The impact plume (circled) measures 6 to 8 km wide. Image Credit: NASA
Nine different instruments aboard LCROSS captured every phase of the Centaur’s impact, from the initial flash, to the debris plume, and even the Centaur’s crater. As LCROSS moved toward the surface, preparing to create the second impact, it continued to return data in the visible, near-infrared and mid-infrared ranges of the spectrum. Excellent images were returned of the Centaur impact crater at a resolution of less than 6.5 feet (2 meters). The images indicate that the new crater measured about 92 feet (28 meters) across.
And yet, with all of the data collected by LCROSS, as well as the space-based and ground-based observing sites, the mission teams aren’t ready to announce whether they observed water ice at the impact site. The recorded data is continuing to undergo a normal scientific review process and NASA will release new information when it becomes available. For more on the LCROSS announcement from October 16, and more on the released images, check out these links:
NASA's Lunar CRater Observation and Sensing Satellite (LCROSS) Mission
http://www.nasa.gov/lcross/VisibleCamera image of the Centaur impact plume from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394553main_Visible-Camera-impact-plume.png
Zoomed-in VisibleCamera image of the Centaur impact plume from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394555main_Visible-Camera-impact-plume-zoom.png
Mid-Infrared Camera Images of Centaur Impact from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394506main_MIR-camera-images-1_full.png
Near-Infrared Camera Image from NASA’s LCROSS Spacecraft
http://www.nasa.gov/394522main_NIR-camera-image-1_full.png
Centaur Impact Images from NASA’s LCROSS Spacecraft
http://www.nasa.gov/mission_pages/LCROSS/main/LCROSS_impact_images.html
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Sunday, October 18, 2009
Jesus Showed Love to Zacchaeus
(Luke 19:1-10)
The basic truths of the Bible can, at times, be the most difficult to practice in our daily lives. Just think about those people you encountered this week who were difficult to love. For that matter, think about those around you this week who might have considered you to be, at least at times, difficult to love. Are you daily showing that you love Jesus?
Luke 19:2 describes Zacchaeus as a chief tax collector in Jericho. Tax collectors were contracted by the Roman government to gather and send money to Rome. As a Jew collecting taxes for the Romans, the occupying government, Zacchaeus quite naturally had a bad reputation among his fellow Jews. Zacchaeus is described as a chief collector, implying that he was responsible for all the taxes of Jericho and that he had other collectors working under him. Zacchaeus' position in itself would have guaranteed him great wealth. But we must understand that the taxing system was open to abuse and extortion was common. Rome required that it get all of its tax, but didn't necessarily mind if its collectors kept extra for themselves in the collection process. We do not know whether Zacchaeus abused the system, but if he had, his position would have given him a greater opportunity to abuse system and gain even more personal wealth.
The people of Jericho heard that Jesus was coming to their town. Like everyone else in Jericho, Zacchaeus wanted to get at least a glimpse of Him. But Zacchaeus had a few things going against him in pursuit of his goal. Firstly, he was short. Secondly he was not well loved by the townspeople. Even so, Zacchaeus persevered. He found a way to see Jesus by climbing a tree near the road. This must have been a humbling and undignified act for Zacchaeus, but doing it suggests that he was motivated by more than just curiosity.
Jesus stopped under the tree and looked up. Since Jesus' disciple Matthew was a tax collector, he may have told Jesus about Zacchaeus. It is also possible that Jesus could have asked someone the name of the person in the tree. Whatever the case, Jesus called Zacchaeus by name and He told Zacchaeus to come down because He was going to stay at Zacchaeus' home that afternoon. Zacchaeus was ecstatic. He came down as fast as he could and gladly welcomed Jesus to his home.
The Bible does not tell us what Jesus and Zacchaeus said and did together, but we can be pretty certain that Jesus communicated love to Zacchaeus. And we can see that Zacchaeus responded to that love. On the spot, Zacchaeus promised to give half of his possessions to the poor. In addition, he would repay out of his remaining half anyone from whom he had stolen. Zacchaeus may have already known that the law required as written in Leviticus 6:5 and Numbers 5:6-7) that anyone who steals must repay and include one-fifth more, or 120 percent. Zacchaeus went way beyond the legal requirement by committing to pay back four times what was stolen, or 400 percent.
Jesus loved Zacchaeus, a man whom others despised. Do you know someone who is difficult to love or like? Ask God to help you show Jesus' love to all that you meet.
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(Luke 19:1-10)
The basic truths of the Bible can, at times, be the most difficult to practice in our daily lives. Just think about those people you encountered this week who were difficult to love. For that matter, think about those around you this week who might have considered you to be, at least at times, difficult to love. Are you daily showing that you love Jesus?
Luke 19:2 describes Zacchaeus as a chief tax collector in Jericho. Tax collectors were contracted by the Roman government to gather and send money to Rome. As a Jew collecting taxes for the Romans, the occupying government, Zacchaeus quite naturally had a bad reputation among his fellow Jews. Zacchaeus is described as a chief collector, implying that he was responsible for all the taxes of Jericho and that he had other collectors working under him. Zacchaeus' position in itself would have guaranteed him great wealth. But we must understand that the taxing system was open to abuse and extortion was common. Rome required that it get all of its tax, but didn't necessarily mind if its collectors kept extra for themselves in the collection process. We do not know whether Zacchaeus abused the system, but if he had, his position would have given him a greater opportunity to abuse system and gain even more personal wealth.
The people of Jericho heard that Jesus was coming to their town. Like everyone else in Jericho, Zacchaeus wanted to get at least a glimpse of Him. But Zacchaeus had a few things going against him in pursuit of his goal. Firstly, he was short. Secondly he was not well loved by the townspeople. Even so, Zacchaeus persevered. He found a way to see Jesus by climbing a tree near the road. This must have been a humbling and undignified act for Zacchaeus, but doing it suggests that he was motivated by more than just curiosity.
Jesus stopped under the tree and looked up. Since Jesus' disciple Matthew was a tax collector, he may have told Jesus about Zacchaeus. It is also possible that Jesus could have asked someone the name of the person in the tree. Whatever the case, Jesus called Zacchaeus by name and He told Zacchaeus to come down because He was going to stay at Zacchaeus' home that afternoon. Zacchaeus was ecstatic. He came down as fast as he could and gladly welcomed Jesus to his home.
The Bible does not tell us what Jesus and Zacchaeus said and did together, but we can be pretty certain that Jesus communicated love to Zacchaeus. And we can see that Zacchaeus responded to that love. On the spot, Zacchaeus promised to give half of his possessions to the poor. In addition, he would repay out of his remaining half anyone from whom he had stolen. Zacchaeus may have already known that the law required as written in Leviticus 6:5 and Numbers 5:6-7) that anyone who steals must repay and include one-fifth more, or 120 percent. Zacchaeus went way beyond the legal requirement by committing to pay back four times what was stolen, or 400 percent.
Jesus loved Zacchaeus, a man whom others despised. Do you know someone who is difficult to love or like? Ask God to help you show Jesus' love to all that you meet.
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Saturday, October 17, 2009
Welcome the Orionids
No, I'm not talking about an alien race coming to Earth, though the Orionids are extra terrestrial. This weekend marks the return of the Orionid meteor shower. The Orionids are one of the best annual showers. The others are the Geminids in December and, the king of the annuals, the Perseids in August.
This shower is caused by dust from periodic Comet Halley (1P/Halley), which last came by in 1986. Halley is also responsible for the Eta Aquarid shower in early May. Under very dark skies, meteors from the Orionid shower actually may be visible from the beginning of October through the first week of November. The Orionid shower is very reliable, giving consistent rates each year. Over the duration of the shower the hourly rate gradually rises and then gradually drops off. The maximum lasts from about October 19 through 23, with the peak around the October 21/October 22 (Wednesday night/Thursday morning. At its peak, the shower is projected to produce 25 to 30 meteors per hour. The meteors will appear to radiate from a point in the sky between the constellations Gemini and Orion (RA 06hrs 20min, Dec +15°). This radiating point is called, appropriately enough, the radiant.
This year, the peak falls around a new moon, which sets not long after sunset. This will improve the chances of a good show even in moderately dark skies.
The Orionid shower radiant rises at about 11 p.m. local time and the best viewing should come after local midnight. To best view the Orionid shower, find a reasonably dark location away from city and neighborhood lights. Bring along a lawn chair, deck chair, or even a blanket if you wish. Also bring along a jacket and maybe a warm beverage. You might be amazed how cool it gets when you are sitting or lying still in the darkness for hours at a time. Once you are situated at your observing site, allow enough time for your eyes to adapt to the darkness--about 15 or 20 minutes. This will permit you to see fainter objects. Binoculars are not necessary. Just slowly scan the sky with your own eyes. And enjoy the show!
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Friday, October 16, 2009
Astronomy is for Everyone, Part One
Several years back, I wrote for my astronomy club a brochure of sorts on the subject of amateur astronomy and its accessibility to everyone. As time and other events permit, I will revisit that document by installments and bring it up today. I present for you today part one of this journey.
“Astronomy is for the amateur as well as the professional. The amateur can see for himself the sights that stirred Galileo, the Herschels, and other great astronomers. A high-school boy may be the first to see a comet, a rug salesman my discover a nova, and a homemaker can observe and map meteor showers.. An amateur's faithful observations of a variable star may be just the data an observatory needs."
--Adapted from "The Sky Observer's Guide", published by Golden Press, New York.
Anyone can be an amateur astronomer. If you like to gaze at the night sky, you are qualified. The great thing about amateur astronomy is that it's such a portable hobby. The only basic requirements are you and a moderately dark sky. You may increase your enjoyment by learning more about the sky with the help of books and magazines. Binoculars and telescopes allow you to gaze even more deeply in to the wonders of the heavens. Photography is another way that some amateurs enrich their observing experience.
Here is some information on the tools available to you. Please use it to answer your questions, direct your attention, and enhance your enjoyment.
Getting Started
A Basic Guide: The beginning observer should have a book on general astronomy. Even a little knowledge greatly increases the pleasure of observing, and it prepares the observer to undertake real astronomical projects. Golden Press puts out some very good pocket-size books that are ready companions for the beginner and the experienced amateur. The are entitled “The Sky Observer's Guide,” “Stars” and “Planets.” Peterson Field Guides and the National Audubon Society both publish excellent astronomy field guides.
A Planisphere: A planisphere, or star-finding wheel, is part of the kit of every astronomer, from the child to the old pro. They consist of a wheel illustrated with night time objects, attached at the center to a second piece, and covered with a third piece that allows a portion of the wheel to be seen through a circular or oval window. They are usually made of thick paper or cardboard. By turning the wheel to indicate your time and date, the window allows you to see which constellations are in your sky at that moment and where they are located.
Internet Star Charts: The Internet includes many free Web sites that have very good sky chart software applications. If you do not have personal access to the Internet, go to your local library to access these sites. Here are just a few of the many available online. I note these because of my greater experience with them.
Chartes du Ciel / Sky Charts
http://www.stargazing.net/astropc/
Heavens Above, hosted by GSOC
http://www.heavens-above.com/
Sky and Telescope.com’s Interactive Sky Chart
http://skyandtelescope.com/observing/skychart/
SkyMaps.com
http://www.skymaps.com/
End of Part One. Look for Part Two in the coming days.
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Several years back, I wrote for my astronomy club a brochure of sorts on the subject of amateur astronomy and its accessibility to everyone. As time and other events permit, I will revisit that document by installments and bring it up today. I present for you today part one of this journey.
“Astronomy is for the amateur as well as the professional. The amateur can see for himself the sights that stirred Galileo, the Herschels, and other great astronomers. A high-school boy may be the first to see a comet, a rug salesman my discover a nova, and a homemaker can observe and map meteor showers.. An amateur's faithful observations of a variable star may be just the data an observatory needs."
--Adapted from "The Sky Observer's Guide", published by Golden Press, New York.
Anyone can be an amateur astronomer. If you like to gaze at the night sky, you are qualified. The great thing about amateur astronomy is that it's such a portable hobby. The only basic requirements are you and a moderately dark sky. You may increase your enjoyment by learning more about the sky with the help of books and magazines. Binoculars and telescopes allow you to gaze even more deeply in to the wonders of the heavens. Photography is another way that some amateurs enrich their observing experience.
Here is some information on the tools available to you. Please use it to answer your questions, direct your attention, and enhance your enjoyment.
Getting Started
A Basic Guide: The beginning observer should have a book on general astronomy. Even a little knowledge greatly increases the pleasure of observing, and it prepares the observer to undertake real astronomical projects. Golden Press puts out some very good pocket-size books that are ready companions for the beginner and the experienced amateur. The are entitled “The Sky Observer's Guide,” “Stars” and “Planets.” Peterson Field Guides and the National Audubon Society both publish excellent astronomy field guides.
A Planisphere: A planisphere, or star-finding wheel, is part of the kit of every astronomer, from the child to the old pro. They consist of a wheel illustrated with night time objects, attached at the center to a second piece, and covered with a third piece that allows a portion of the wheel to be seen through a circular or oval window. They are usually made of thick paper or cardboard. By turning the wheel to indicate your time and date, the window allows you to see which constellations are in your sky at that moment and where they are located.
Internet Star Charts: The Internet includes many free Web sites that have very good sky chart software applications. If you do not have personal access to the Internet, go to your local library to access these sites. Here are just a few of the many available online. I note these because of my greater experience with them.
Chartes du Ciel / Sky Charts
http://www.stargazing.net/astropc/
Heavens Above, hosted by GSOC
http://www.heavens-above.com/
Sky and Telescope.com’s Interactive Sky Chart
http://skyandtelescope.com/observing/skychart/
SkyMaps.com
http://www.skymaps.com/
End of Part One. Look for Part Two in the coming days.
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Thursday, October 15, 2009
Barnard’s Little Galaxy
On Wednesday, The European Southern Observatory (ESO) released a new image of NGC 6822, also known as Barnard’s Galaxy. It is classified as an irregular dwarf galaxy because of its unusual shape and relatively small size--if a galaxy can be classified in any way as small. NGC 6822 is located about 1.63 million light-years away, in the direction of the constellation Sagittarius. Because of its relative closeness, NGC 6822 is classified as a member of the Local Group of galaxies—our galactic neighborhood. The galaxy was discovered in 1881 by American amateur-turned-professional astronomer Edward Emerson Barnard (1857 – 1932) using a six-inch refractor telescope. Studying strange galaxies like NGC 6822 help astronomers understand how galaxies interact, evolve and occasionally gobble up each other, leaving behind these galactic crumbs.
![]()
An irregular dwarf galaxy is a dwarf galaxy that lacks any apparent structure or a uniform shape. In recent times astronomers have gradually placed higher and higher importance in the study of irregular dwarf galaxies as a method of understanding the evolution of galaxies in general, because there are so many examples near to our own galaxy. Their study can help us understand important issues such as the occurrence of galactic winds, the chemical enrichment of the interstellar and intergalactic media, and the photometric—brightness—evolution of galaxies. In addition, their low level of evolution, as implied by their low amounts of metals and their high amounts of gases, makes them the most similar to early galaxies and, therefore, the most useful for research into what primordial galaxies may have been like. Some have also suggested that these nearby irregular dwarf galaxies are similar to the many faint blue galaxies seen in deep galaxy counts. To learn more about the ESO’s latest image release, and to learn more about the ESO, check out these links:
NGC 6822, Barnard’s Galaxy, as recorded by the Wide Field Imager attached to the 2.2-meter MPG/ESO telescope at ESO’s La Silla Observatory in northern Chile. Image Credit: ESO
http://www.eso.org/gallery/v/ESOPIA/Galaxies/phot-38a-09-fullres.tif.html
European Southern Observatory
http://www.eso.org/
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On Wednesday, The European Southern Observatory (ESO) released a new image of NGC 6822, also known as Barnard’s Galaxy. It is classified as an irregular dwarf galaxy because of its unusual shape and relatively small size--if a galaxy can be classified in any way as small. NGC 6822 is located about 1.63 million light-years away, in the direction of the constellation Sagittarius. Because of its relative closeness, NGC 6822 is classified as a member of the Local Group of galaxies—our galactic neighborhood. The galaxy was discovered in 1881 by American amateur-turned-professional astronomer Edward Emerson Barnard (1857 – 1932) using a six-inch refractor telescope. Studying strange galaxies like NGC 6822 help astronomers understand how galaxies interact, evolve and occasionally gobble up each other, leaving behind these galactic crumbs.
NGC 6822, Barnard’s Galaxy, as recorded by the Wide Field Imager attached to the 2.2-meter MPG/ESO telescope at ESO’s La Silla Observatory in northern Chile. Image Credit: ESO
An irregular dwarf galaxy is a dwarf galaxy that lacks any apparent structure or a uniform shape. In recent times astronomers have gradually placed higher and higher importance in the study of irregular dwarf galaxies as a method of understanding the evolution of galaxies in general, because there are so many examples near to our own galaxy. Their study can help us understand important issues such as the occurrence of galactic winds, the chemical enrichment of the interstellar and intergalactic media, and the photometric—brightness—evolution of galaxies. In addition, their low level of evolution, as implied by their low amounts of metals and their high amounts of gases, makes them the most similar to early galaxies and, therefore, the most useful for research into what primordial galaxies may have been like. Some have also suggested that these nearby irregular dwarf galaxies are similar to the many faint blue galaxies seen in deep galaxy counts. To learn more about the ESO’s latest image release, and to learn more about the ESO, check out these links:
NGC 6822, Barnard’s Galaxy, as recorded by the Wide Field Imager attached to the 2.2-meter MPG/ESO telescope at ESO’s La Silla Observatory in northern Chile. Image Credit: ESO
http://www.eso.org/gallery/v/ESOPIA/Galaxies/phot-38a-09-fullres.tif.html
European Southern Observatory
http://www.eso.org/
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Wednesday, October 14, 2009
Cosmic Dark Ages
Most folks are familiar with the historical concept of the Dark Ages. This term is applied to the time in Western European history between the fall of the Roman Empire and latter portion of the Middle Ages. This time is often considered by many to have a great lack of the light of knowledge. And so it was classified as a “dark” age in Western European history.
Now, did you know that in the cosmological theory of the Big Bang there was also a Dark Age? It is suggested that there was, but in this case it was a literal age of darkness.
Some time after the Big Bang, or the great expansion, as it is sometimes called, there was a time of about 800 million years when our universe had no light whatsoever. The energy from the Big Bang had subsided and cooled to the point that it no longer radiated visible light. The hydrogen and helium from the Big Bang may have begun to bunch and clump—the very beginning of star formation—but none had reached the stage where fusion would turn on in their cores and eventually cause their outer layers to shine. We are talking about a really, really dark time, here.
Astronomers want to study this time as part of their overall understanding of the universe formation, but how can they study what they cannot see? Well, rather than observing visible light, they are studying the radio-wave portion of the electromagnetic spectrum. They are hoping that this will allow them to look back to the end of this Dark Age, to the point when the first stars began to shine, when the first black holes began to accrete matter, and when the first galaxies began to form. These were the building blocks of the universe we see today.
Because the desired radio signals are so far away and so faint, it is easy to confuse them with background interference. So in order to detect the proper radio signals and filter out the background noise, the radio telescopes for the task must be really, really large. To meet this need, at least three projects are currently under construction. One is in the U.S., another is in Europe.
The U.S. project is the Long Wavelength Array (LWA), currently under construction in the desert west of Socorro, New Mexico. The final array, scheduled for completion in 2010, will consist of 13,000 antennas. The LWA is sponsored by the University of New Mexico, the Los Alamos National Laboratory, the Naval Research Laboratory and others.
The Europe project is the Low Frequency Array (LOFAR), which will stretch 5,000 antennas across northern Europe from a center in the Netherlands. LOFAR is currently scheduled for completion in 2011. The prime sponsor for LOFAR is ASTRON, the Netherlands Institute for Radio Astronomy. Astronomers in England, France, Germany, Poland and Sweden are also involved.
The Australia project is the Murchison Widefield Array (MWA), currently under construction near Mileura Station in Western Australia. The array will consist of 8,192 antennas spread across the western Australia outback. Because of its location, it is also called the Mileura Widefield Array. The MWA is sponsored by MIT, the National Science Foundation, the U.S. Air Force and the Australian Research Council.
These new radio telescopes will look for faint radio waves from the time the universe was 380,000 years to roughly a billion years old. The signals are coming from ancient hydrogen, which can be detected by a special line in the electromagnetic spectrum. Tiny variations in the hydrogen line indicate regions of slightly higher or lower density in the early universe. Over time, gravity accelerated the growth of these clumps, which became the seeds of the first generation of stars and galaxies.
Astronomers aren’t exactly sure about how long the Dark Age lasted, and they aren’t sure how much they will be able to detect of the end of this age and the beginning of star formation. Basically, they won’t know for sure about a lot of things until they try to find out. And of course, that’s what makes astronomers and other scientists so excited in the first place—trying to find things out.
To learn more about these three projects, and to learn a bit more about the cosmic Dark Age, check out these links:
The Long Wavelength Array (LWA)
http://lwa.unm.edu/
The Netherlands Institute for Radio Astronomy, prime sponsor for LOFAR
http://www.astron.nl/
The Murchison Widefield Array (MWA)
http://www.mwatelescope.org/
YouTube video, “Cosmic Dark Age – a time without stars,” an excerpt from the BBC Horizon Science documentary “The Death Start,” (BBC Worldwide, running time 3 minutes 47 seconds)
http://www.youtube.com/watch?v=V3mgHCuhfQk
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Most folks are familiar with the historical concept of the Dark Ages. This term is applied to the time in Western European history between the fall of the Roman Empire and latter portion of the Middle Ages. This time is often considered by many to have a great lack of the light of knowledge. And so it was classified as a “dark” age in Western European history.
Now, did you know that in the cosmological theory of the Big Bang there was also a Dark Age? It is suggested that there was, but in this case it was a literal age of darkness.
Some time after the Big Bang, or the great expansion, as it is sometimes called, there was a time of about 800 million years when our universe had no light whatsoever. The energy from the Big Bang had subsided and cooled to the point that it no longer radiated visible light. The hydrogen and helium from the Big Bang may have begun to bunch and clump—the very beginning of star formation—but none had reached the stage where fusion would turn on in their cores and eventually cause their outer layers to shine. We are talking about a really, really dark time, here.
Astronomers want to study this time as part of their overall understanding of the universe formation, but how can they study what they cannot see? Well, rather than observing visible light, they are studying the radio-wave portion of the electromagnetic spectrum. They are hoping that this will allow them to look back to the end of this Dark Age, to the point when the first stars began to shine, when the first black holes began to accrete matter, and when the first galaxies began to form. These were the building blocks of the universe we see today.
Because the desired radio signals are so far away and so faint, it is easy to confuse them with background interference. So in order to detect the proper radio signals and filter out the background noise, the radio telescopes for the task must be really, really large. To meet this need, at least three projects are currently under construction. One is in the U.S., another is in Europe.
The U.S. project is the Long Wavelength Array (LWA), currently under construction in the desert west of Socorro, New Mexico. The final array, scheduled for completion in 2010, will consist of 13,000 antennas. The LWA is sponsored by the University of New Mexico, the Los Alamos National Laboratory, the Naval Research Laboratory and others.
The Europe project is the Low Frequency Array (LOFAR), which will stretch 5,000 antennas across northern Europe from a center in the Netherlands. LOFAR is currently scheduled for completion in 2011. The prime sponsor for LOFAR is ASTRON, the Netherlands Institute for Radio Astronomy. Astronomers in England, France, Germany, Poland and Sweden are also involved.
The Australia project is the Murchison Widefield Array (MWA), currently under construction near Mileura Station in Western Australia. The array will consist of 8,192 antennas spread across the western Australia outback. Because of its location, it is also called the Mileura Widefield Array. The MWA is sponsored by MIT, the National Science Foundation, the U.S. Air Force and the Australian Research Council.
These new radio telescopes will look for faint radio waves from the time the universe was 380,000 years to roughly a billion years old. The signals are coming from ancient hydrogen, which can be detected by a special line in the electromagnetic spectrum. Tiny variations in the hydrogen line indicate regions of slightly higher or lower density in the early universe. Over time, gravity accelerated the growth of these clumps, which became the seeds of the first generation of stars and galaxies.
Astronomers aren’t exactly sure about how long the Dark Age lasted, and they aren’t sure how much they will be able to detect of the end of this age and the beginning of star formation. Basically, they won’t know for sure about a lot of things until they try to find out. And of course, that’s what makes astronomers and other scientists so excited in the first place—trying to find things out.
To learn more about these three projects, and to learn a bit more about the cosmic Dark Age, check out these links:
The Long Wavelength Array (LWA)
http://lwa.unm.edu/
The Netherlands Institute for Radio Astronomy, prime sponsor for LOFAR
http://www.astron.nl/
The Murchison Widefield Array (MWA)
http://www.mwatelescope.org/
YouTube video, “Cosmic Dark Age – a time without stars,” an excerpt from the BBC Horizon Science documentary “The Death Start,” (BBC Worldwide, running time 3 minutes 47 seconds)
http://www.youtube.com/watch?v=V3mgHCuhfQk
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Tuesday, October 13, 2009
NGC 2623's Galactic Merger
NGC 2623 is one of those deep-sky objects recorded in the 19th-century compendium called “A New General Catalogue of Nebulae and Clusters of Stars,” or for short, the “New General Catalogue” (NGC). Danish-Irish astronomer J. L. E. Dreyer published the NCG for the Royal Astronomical Society using primarily the recorded observations from William Herschel, is son, John Herschel.
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The object NGC 2623 is located in the direction of the constellation Cancer, the Crab, about 250 million light-years away. When viewed in dark skies with a medium-sized telescope, with about a 12-inch aperture or so, the object has a strange, swirling shape. It has the appearance of a bird flying head-on at the observer, with one wing sweeping up, the other wing sweeping down, and the main mass of the body clumped in the center. This object is a galaxy. Or more accurately, two galaxies which are still in the process of merging into one.
Over the last century of study, astronomers have learned that it is not so uncommon for galaxies to collide and merge into larger galaxies. In fact, our own Milky Way galaxy has a date with the Andromeda galaxy in about 3 billion years. But that's another story…
Galaxies that merge do not just bump into each other. They contain lots of space between their stars, after all. But the interaction process does have a dramatic effect on each of the galaxies. Studies show that as galaxies approach one another massive amounts of gas are pulled from each galaxy toward the center of the other, until the two ultimately merge into one massive galaxy. NGC 2623 is in the late stages of the merging process. The centers of the original galaxies are combined, but stretching out from the center are two curling tails of young stars—these are the “wings” I referenced in my shape description earlier. The curling tails are a telltale sign that a galactic merger has occurred. During one of these mergers, the dramatic exchange of mass and gases initiates the process of star formation. The young stars visible in the two tails were created by this process.
Some of the galactic mergers, like that of NGC 2623, can result in an active galactic nucleus, where one of the super-massive black holes—from the center of one of the two original galaxies—is stirred into action. Matter is pulled toward the black hole, forming an accretion disc. The energy released by this activity heats up the disc, causing it to emit across a wide range of the electromagnetic spectrum.
NGC 2623 is so bright in the infrared that it has become a member of the group of very luminous infrared galaxies (LIRG) and it has been extensively studied as the part of the Great Observatories All-sky LIRG Survey (GOALS) project. The GOALS project combines data from some of the most advanced space-based telescopes, including Hubble. Additional data from infrared and X-ray telescopes can further characterize objects like active galactic nuclei and nuclear star formation by revealing what is unseen at visible wavelengths.
The GOALS project includes data from NASA/ESA's Hubble Space Telescope, NASA's Spitzer Space Telescope, NASA's Chandra X-ray Observatory and NASA's Galaxy Evolution Explorer (GALEX). The joint efforts of these powerful observing facilities have provided a clearer picture of our local Universe. To learn more about NGC 2326 and the Hubble Space Telescope, check out these links:
NGC 2326, at the European Home Page for the NASA/ESA Hubble Space Telescope
http://www.spacetelescope.org/images/html/heic0912a.html
NASA’s Home Page for the Hubble Space Telescope
http://www.nasa.gov/hubble/
The Space Telescope Science Institute (STScI)
http://www.stsci.edu/
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NGC 2623 is one of those deep-sky objects recorded in the 19th-century compendium called “A New General Catalogue of Nebulae and Clusters of Stars,” or for short, the “New General Catalogue” (NGC). Danish-Irish astronomer J. L. E. Dreyer published the NCG for the Royal Astronomical Society using primarily the recorded observations from William Herschel, is son, John Herschel.
NGC 2623, as recently imaged by ESA/NASA Hubble Space Telescope. Image Credit: ESA/NASA
The object NGC 2623 is located in the direction of the constellation Cancer, the Crab, about 250 million light-years away. When viewed in dark skies with a medium-sized telescope, with about a 12-inch aperture or so, the object has a strange, swirling shape. It has the appearance of a bird flying head-on at the observer, with one wing sweeping up, the other wing sweeping down, and the main mass of the body clumped in the center. This object is a galaxy. Or more accurately, two galaxies which are still in the process of merging into one.
Over the last century of study, astronomers have learned that it is not so uncommon for galaxies to collide and merge into larger galaxies. In fact, our own Milky Way galaxy has a date with the Andromeda galaxy in about 3 billion years. But that's another story…
Galaxies that merge do not just bump into each other. They contain lots of space between their stars, after all. But the interaction process does have a dramatic effect on each of the galaxies. Studies show that as galaxies approach one another massive amounts of gas are pulled from each galaxy toward the center of the other, until the two ultimately merge into one massive galaxy. NGC 2623 is in the late stages of the merging process. The centers of the original galaxies are combined, but stretching out from the center are two curling tails of young stars—these are the “wings” I referenced in my shape description earlier. The curling tails are a telltale sign that a galactic merger has occurred. During one of these mergers, the dramatic exchange of mass and gases initiates the process of star formation. The young stars visible in the two tails were created by this process.
Some of the galactic mergers, like that of NGC 2623, can result in an active galactic nucleus, where one of the super-massive black holes—from the center of one of the two original galaxies—is stirred into action. Matter is pulled toward the black hole, forming an accretion disc. The energy released by this activity heats up the disc, causing it to emit across a wide range of the electromagnetic spectrum.
NGC 2623 is so bright in the infrared that it has become a member of the group of very luminous infrared galaxies (LIRG) and it has been extensively studied as the part of the Great Observatories All-sky LIRG Survey (GOALS) project. The GOALS project combines data from some of the most advanced space-based telescopes, including Hubble. Additional data from infrared and X-ray telescopes can further characterize objects like active galactic nuclei and nuclear star formation by revealing what is unseen at visible wavelengths.
The GOALS project includes data from NASA/ESA's Hubble Space Telescope, NASA's Spitzer Space Telescope, NASA's Chandra X-ray Observatory and NASA's Galaxy Evolution Explorer (GALEX). The joint efforts of these powerful observing facilities have provided a clearer picture of our local Universe. To learn more about NGC 2326 and the Hubble Space Telescope, check out these links:
NGC 2326, at the European Home Page for the NASA/ESA Hubble Space Telescope
http://www.spacetelescope.org/images/html/heic0912a.html
NASA’s Home Page for the Hubble Space Telescope
http://www.nasa.gov/hubble/
The Space Telescope Science Institute (STScI)
http://www.stsci.edu/
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Monday, October 12, 2009
NASA Refines the Path of Asteroid Apophis, Again
Last Wednesday, October 7, NASA announced updated calculations on the path of Asteroid 99942 Apophis. Discovered June 19, 2004, is a near-Earth asteroid approximately 250 yards across—the length of two-and-one-half football fields.
Apophis was initially thought to have a 2.7 percent chance of striking Earth or Earth’s moon in 2029. Additional observations ruled out the possibility of a 2029 impact, but this led to a concern that on that 2029 pass Apophis might move through a region of space no more than about 600 meters across—called a gravitational keyhole—that would set up Apophis for an Earth impact on April 13, 2036. This concern was maintained until August 2006, when more observations ruled out this possibility. With the October 7 announcement, the probably of an April 13, 2036 impact is calculated as 1 in 250,000. While this is a good thing, Apophis will still go into the record books during its pass on Friday, April 13, 2029. On that date, Apophis is expected to come closer than 29,450 kilometers (18,300 miles) from Earth’s surface. Let’s put that distance in perspective.
- Earth’s moon orbits at about 384,400 km (238,900 mi), which is 354,950 km (220,600 mi) above the Apophis pass.
- Geosynchronous satellites—including communication and television satellites—orbit at about 35,786 km (22,236 mi), which is 6,336 km (3,936 mi) above the Apophis pass.
- Global Positioning System (GPS) satellites orbit at about 20,200 km (12,550 mi), which is 9,250 km (5,750 mi) below the Apophis pass.
- NASA’s Hubble Space Telescope orbits at 559 km (347 mi), which is 28,891 km (17,953 mi) below the Apophis pass.
- The International Space Station orbits at an average distance of 347 km (187 mi), which is well below the Apophis pass.
What have we learned from this? Well, we’ve learned that while Apophis will not actually strike Earth, it will definitely pass through Earth’s network of satellites. That may mean nothing. Could Apophis hit a satellite on its way through? Probably not. After all, there is a lot of space up there. Though, as we have seen in the last year or so, some things are able to beat the odds from time to time, and run into each other up there. Of course, the event is still 20 years in the future and who knows how many satellites will be in orbit by then? Low-probability satellite impacts aside, could the passage of Apophis influence our satellite network? Again, probably not, but it definitely continues to bear close watching for the scientific interest.
Beyond 2029, the latest calculations show another possible close encounter with Earth in 2068 with a chance of impact currently estimated at approximately three-in-a-million. This estimate is expected to be more highly refined, with the risk probably diminishing, as additional years of observations are made.
The prediction of asteroid orbits is a science based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids—Ceres, Pallas and Vesta.
Asteroids and comets which pass close to Earth are detected by NASA using both ground and space-based telescopes. The Near-Earth Objects Observations Program, also known as “Spaceguard,” discovers these objects, characterizes a subset of them and plots their orbits to determine if any object could b potentially hazardous to those of us on Earth. For more information about asteroids and near-Earth objects, check out these links:
Twitter Page for NASA’s Asteroid Watch
http://twitter.com/asteroidwatch
NASA’s Asteroid Watch
http://www.jpl.nasa.gov/asteroidwatch
NASA’s Near-Earth Object Program
http://www.jpl.nasa.gov/asteroidwatch
-
Last Wednesday, October 7, NASA announced updated calculations on the path of Asteroid 99942 Apophis. Discovered June 19, 2004, is a near-Earth asteroid approximately 250 yards across—the length of two-and-one-half football fields.
Apophis was initially thought to have a 2.7 percent chance of striking Earth or Earth’s moon in 2029. Additional observations ruled out the possibility of a 2029 impact, but this led to a concern that on that 2029 pass Apophis might move through a region of space no more than about 600 meters across—called a gravitational keyhole—that would set up Apophis for an Earth impact on April 13, 2036. This concern was maintained until August 2006, when more observations ruled out this possibility. With the October 7 announcement, the probably of an April 13, 2036 impact is calculated as 1 in 250,000. While this is a good thing, Apophis will still go into the record books during its pass on Friday, April 13, 2029. On that date, Apophis is expected to come closer than 29,450 kilometers (18,300 miles) from Earth’s surface. Let’s put that distance in perspective.
- Earth’s moon orbits at about 384,400 km (238,900 mi), which is 354,950 km (220,600 mi) above the Apophis pass.
- Geosynchronous satellites—including communication and television satellites—orbit at about 35,786 km (22,236 mi), which is 6,336 km (3,936 mi) above the Apophis pass.
- Global Positioning System (GPS) satellites orbit at about 20,200 km (12,550 mi), which is 9,250 km (5,750 mi) below the Apophis pass.
- NASA’s Hubble Space Telescope orbits at 559 km (347 mi), which is 28,891 km (17,953 mi) below the Apophis pass.
- The International Space Station orbits at an average distance of 347 km (187 mi), which is well below the Apophis pass.
What have we learned from this? Well, we’ve learned that while Apophis will not actually strike Earth, it will definitely pass through Earth’s network of satellites. That may mean nothing. Could Apophis hit a satellite on its way through? Probably not. After all, there is a lot of space up there. Though, as we have seen in the last year or so, some things are able to beat the odds from time to time, and run into each other up there. Of course, the event is still 20 years in the future and who knows how many satellites will be in orbit by then? Low-probability satellite impacts aside, could the passage of Apophis influence our satellite network? Again, probably not, but it definitely continues to bear close watching for the scientific interest.
Beyond 2029, the latest calculations show another possible close encounter with Earth in 2068 with a chance of impact currently estimated at approximately three-in-a-million. This estimate is expected to be more highly refined, with the risk probably diminishing, as additional years of observations are made.
The prediction of asteroid orbits is a science based on a physical model of the solar system which includes the gravitational influence of the sun, moon, other planets and the three largest asteroids—Ceres, Pallas and Vesta.
Asteroids and comets which pass close to Earth are detected by NASA using both ground and space-based telescopes. The Near-Earth Objects Observations Program, also known as “Spaceguard,” discovers these objects, characterizes a subset of them and plots their orbits to determine if any object could b potentially hazardous to those of us on Earth. For more information about asteroids and near-Earth objects, check out these links:
Twitter Page for NASA’s Asteroid Watch
http://twitter.com/asteroidwatch
NASA’s Asteroid Watch
http://www.jpl.nasa.gov/asteroidwatch
NASA’s Near-Earth Object Program
http://www.jpl.nasa.gov/asteroidwatch
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