2003 January 10
The Crab that Played with the Planet
Credit & Copyright: Ron Wodaski, Newastro Remote Telescope at New Mexico Skies
Wandering through the constellation Taurus, Saturn made its closest approach to planet Earth last month, tilting its lovely rings toward appreciative skygazers while rising high in midnight skies. On January 4th and 5th, Saturn also crossed in front of the high and far-off Crab Nebula (M1), a cosmic cloud of debris from a stellar explosion and first on the list of astronomer Charles Messier's celestial sights. But Saturn and the Crab made poor playmates, as light from the bright planet overwhelmed the the diffuse nebula, all but hiding the Crab during the transit. Taken on January 2nd, a few days before their closest encounter, this composite digital image illustrates the problem. The subtle nebula is just visible at the right, while on the left, light from a drastically over-exposed Saturn overflows its pixels. Composited into the image is a correctly exposed picture of ringed Saturn with the Saturnian moons labeled. The well-exposed Saturn image was also taken on January 2nd, but captured with an exposure lasting only a fraction of a second, in contrast with the tens of seconds of exposure time required to reveal the Crab.
The Crab that Played with the Planet
Credit & Copyright: Ron Wodaski, Newastro Remote Telescope at New Mexico Skies
Wandering through the constellation Taurus, Saturn made its closest approach to planet Earth last month, tilting its lovely rings toward appreciative skygazers while rising high in midnight skies. On January 4th and 5th, Saturn also crossed in front of the high and far-off Crab Nebula (M1), a cosmic cloud of debris from a stellar explosion and first on the list of astronomer Charles Messier's celestial sights. But Saturn and the Crab made poor playmates, as light from the bright planet overwhelmed the the diffuse nebula, all but hiding the Crab during the transit. Taken on January 2nd, a few days before their closest encounter, this composite digital image illustrates the problem. The subtle nebula is just visible at the right, while on the left, light from a drastically over-exposed Saturn overflows its pixels. Composited into the image is a correctly exposed picture of ringed Saturn with the Saturnian moons labeled. The well-exposed Saturn image was also taken on January 2nd, but captured with an exposure lasting only a fraction of a second, in contrast with the tens of seconds of exposure time required to reveal the Crab.
2003 January 11
Apollo 17: Boulder in Stereo
Credit: Apollo 17, NASA (Stereo Image by Patrick Vantuyne)
Humans left the Moon over thirty years ago, but donning red-blue glasses (red for the left eye) you can share this excellent stereo perspective view of their last stomping ground. Recorded by Eugene Cernan, the scene depicts his fellow astronaut and geologist Harrison Schmitt next to a large split boulder on the floor of the narrow Taurus-Littrow valley located at the eastern edge of the lunar Mare Serenitatis. Parked nearby, their lunar rover is visible beyond the boulder at the right. During their stay the Apollo 17 astronauts explored the unusually dark terrain at the Taurus-Littrow landing site and deployed explosives to test the internal geology of the Moon. Apollo 17 returned the most lunar rocks and soil samples of any lunar mission.
Apollo 17: Boulder in Stereo
Credit: Apollo 17, NASA (Stereo Image by Patrick Vantuyne)
Humans left the Moon over thirty years ago, but donning red-blue glasses (red for the left eye) you can share this excellent stereo perspective view of their last stomping ground. Recorded by Eugene Cernan, the scene depicts his fellow astronaut and geologist Harrison Schmitt next to a large split boulder on the floor of the narrow Taurus-Littrow valley located at the eastern edge of the lunar Mare Serenitatis. Parked nearby, their lunar rover is visible beyond the boulder at the right. During their stay the Apollo 17 astronauts explored the unusually dark terrain at the Taurus-Littrow landing site and deployed explosives to test the internal geology of the Moon. Apollo 17 returned the most lunar rocks and soil samples of any lunar mission.
2003 January 12
A Spherule from Outer Space
Credit: Timothy Culler (UCB) et al., Apollo 11 Crew, NASA
When a meteorite strikes the Moon, the energy of the impact melts some of the splattering rock, a fraction of which might cool into tiny glass beads. Many of these glass beads were present in lunar soil samples returned to Earth by the Apollo missions. Pictured above is one such glass spherule that measures only a quarter of a millimeter across. This spherule is particularly interesting because it has been victim to an even smaller impact. A miniature crater is visible on the upper left, surrounded by a fragmented area caused by the shockwaves of the small impact. By dating many of these impacts, some astronomers estimate that cratering on our Moon increased roughly 500 million years ago and continues even today.
A Spherule from Outer Space
Credit: Timothy Culler (UCB) et al., Apollo 11 Crew, NASA
When a meteorite strikes the Moon, the energy of the impact melts some of the splattering rock, a fraction of which might cool into tiny glass beads. Many of these glass beads were present in lunar soil samples returned to Earth by the Apollo missions. Pictured above is one such glass spherule that measures only a quarter of a millimeter across. This spherule is particularly interesting because it has been victim to an even smaller impact. A miniature crater is visible on the upper left, surrounded by a fragmented area caused by the shockwaves of the small impact. By dating many of these impacts, some astronomers estimate that cratering on our Moon increased roughly 500 million years ago and continues even today.
2003 January 13
The Dumbbell Nebula in Hydrogen and Oxygen
Credit & Copyright: George Jacoby (NOAO) et al., WIYN, AURA, NOAO, NSF
The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of "annoying" diffuse objects not to be confused with "interesting" comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core. M27 is one of the brightest planetary nebulae on the sky, and can be seen in the constellation Vulpecula with binoculars. It takes light about 1000 years to reach us from M27, shown above, digitally sharpened, in three isolated colors emitted by hydrogen and oxygen. Understanding the physics and significance of M27 was well beyond 18th century science. Even today, many things remain mysterious about bipolar planetary nebula like M27, including the physical mechanism that expels a low-mass star's gaseous outer-envelope, leaving an X-ray hot white dwarf.
The Dumbbell Nebula in Hydrogen and Oxygen
Credit & Copyright: George Jacoby (NOAO) et al., WIYN, AURA, NOAO, NSF
The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of "annoying" diffuse objects not to be confused with "interesting" comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core. M27 is one of the brightest planetary nebulae on the sky, and can be seen in the constellation Vulpecula with binoculars. It takes light about 1000 years to reach us from M27, shown above, digitally sharpened, in three isolated colors emitted by hydrogen and oxygen. Understanding the physics and significance of M27 was well beyond 18th century science. Even today, many things remain mysterious about bipolar planetary nebula like M27, including the physical mechanism that expels a low-mass star's gaseous outer-envelope, leaving an X-ray hot white dwarf.
2003 January 14
0313-192: The Wrong Galaxy
Credit: W. Keel (Univ. Alabama), M. Ledlow (Gemini Obs.), F. Owen (NRAO), AUI,NSF, NASA
Centered above is distant galaxy 0313-192, some one billion light-years away. Radio emission from the galaxy has been mapped by the National Radio Astronomy Observatory's Very Large Array and is shown in red, composited with a visible light image from the Hubble Space Telescope's new Advanced Camera for Surveys. Dust lanes and other features in the Hubble image as well as infrared Gemini telescope data demonstrate clearly that 0313-192 is a spiral galaxy seen edge-on. (Note the unrelated spiral galaxy seen face-on above and to the right.) For years, double cosmic clouds of radio emission such as those flanking this spiral galaxy's core have been studied and cataloged. But, at least until now, such radio sources were only known to arise from the cores of giant elliptical galaxies or in violent merging galaxy systems, making 0313-192 the wrong kind of galaxy to be found in this scenario. Astronomers are searching for clues to why this spiral galaxy, potentially similar to our own Milky Way, shows such powerful activity.
0313-192: The Wrong Galaxy
Credit: W. Keel (Univ. Alabama), M. Ledlow (Gemini Obs.), F. Owen (NRAO), AUI,NSF, NASA
Centered above is distant galaxy 0313-192, some one billion light-years away. Radio emission from the galaxy has been mapped by the National Radio Astronomy Observatory's Very Large Array and is shown in red, composited with a visible light image from the Hubble Space Telescope's new Advanced Camera for Surveys. Dust lanes and other features in the Hubble image as well as infrared Gemini telescope data demonstrate clearly that 0313-192 is a spiral galaxy seen edge-on. (Note the unrelated spiral galaxy seen face-on above and to the right.) For years, double cosmic clouds of radio emission such as those flanking this spiral galaxy's core have been studied and cataloged. But, at least until now, such radio sources were only known to arise from the cores of giant elliptical galaxies or in violent merging galaxy systems, making 0313-192 the wrong kind of galaxy to be found in this scenario. Astronomers are searching for clues to why this spiral galaxy, potentially similar to our own Milky Way, shows such powerful activity.
2003 January 15
Ringed Planet Uranus
Credit: E. Lellouch, T. Encrenaz (Obs. Paris), J. Cuby , A. Jaunsen (ESO-Chile), VLT Antu, ESO
Yes it does look like Saturn, but Saturn is only one of four giant ringed planets in our Solar System. And while Saturn has the brightest rings, this system of rings and moons actually belongs to planet Uranus, imaged here in near-infrared light by the Antu telescope at the ESO Paranal Observatory in Chile. Since gas giant Uranus' methane-laced atmosphere absorbs sunlight at near-infrared wavelengths the planet appears substantially darkened, improving the contrast between the otherwise relatively bright planet and the normally faint rings. In fact, the narrow Uranian rings are all but impossible to see in visible light with earthbound telescopes and were discovered only in 1977 as careful astronomers noticed the then unknown rings blocking light from background stars. The rings are thought to be younger than 100 million years and may be formed of debris from the collision of a small moon with a passing comet or asteroid-like object. With moons named for characters in Shakespeare's plays, the distant ringed world Uranus was last visited in 1986 by the Voyager 2 spacecraft.
Ringed Planet Uranus
Credit: E. Lellouch, T. Encrenaz (Obs. Paris), J. Cuby , A. Jaunsen (ESO-Chile), VLT Antu, ESO
Yes it does look like Saturn, but Saturn is only one of four giant ringed planets in our Solar System. And while Saturn has the brightest rings, this system of rings and moons actually belongs to planet Uranus, imaged here in near-infrared light by the Antu telescope at the ESO Paranal Observatory in Chile. Since gas giant Uranus' methane-laced atmosphere absorbs sunlight at near-infrared wavelengths the planet appears substantially darkened, improving the contrast between the otherwise relatively bright planet and the normally faint rings. In fact, the narrow Uranian rings are all but impossible to see in visible light with earthbound telescopes and were discovered only in 1977 as careful astronomers noticed the then unknown rings blocking light from background stars. The rings are thought to be younger than 100 million years and may be formed of debris from the collision of a small moon with a passing comet or asteroid-like object. With moons named for characters in Shakespeare's plays, the distant ringed world Uranus was last visited in 1986 by the Voyager 2 spacecraft.
2003 January 16
NGC 1700: Elliptical Galaxy and Rotating Disk
Credit: Thomas S. Statler, Brian R. McNamara (Ohio Univ.), CXC, NASA
In spiral galaxies, majestic winding arms of young stars and interstellar gas and dust rotate in a disk around a bulging galactic nucleus. Elliptical galaxies seem to be simpler, randomly swarming with old stars and lacking gas and dust. So astronomers were excited to find that NGC 1700, a young elliptical galaxy about 160 million light-years away, shows evidence for a 90,000 light-year wide rotating disk of multi-million degree hot gas. The evidence comes from data recorded by the orbiting Chandra Observatory, whose sharp x-ray image of NGC 1700 is seen above. Balancing gravity, the rotation of the x-ray hot disk, the largest of its type yet discovered, gives the galaxy a pronounced boxy profile in this false-color picture. Theories about the origin of the disk suggest that NGC 1700 may be the result of a cosmic scale galactic merger, perhaps between a spiral and elliptical galaxy. NGC 1700 is just visible with small telescopes toward the flowing constellation Eridanus.
NGC 1700: Elliptical Galaxy and Rotating Disk
Credit: Thomas S. Statler, Brian R. McNamara (Ohio Univ.), CXC, NASA
In spiral galaxies, majestic winding arms of young stars and interstellar gas and dust rotate in a disk around a bulging galactic nucleus. Elliptical galaxies seem to be simpler, randomly swarming with old stars and lacking gas and dust. So astronomers were excited to find that NGC 1700, a young elliptical galaxy about 160 million light-years away, shows evidence for a 90,000 light-year wide rotating disk of multi-million degree hot gas. The evidence comes from data recorded by the orbiting Chandra Observatory, whose sharp x-ray image of NGC 1700 is seen above. Balancing gravity, the rotation of the x-ray hot disk, the largest of its type yet discovered, gives the galaxy a pronounced boxy profile in this false-color picture. Theories about the origin of the disk suggest that NGC 1700 may be the result of a cosmic scale galactic merger, perhaps between a spiral and elliptical galaxy. NGC 1700 is just visible with small telescopes toward the flowing constellation Eridanus.
2003 January 17
Stars and the Bubble Nebula
Credit & Copyright: Brian Lula
Seemingly adrift in a cosmic sea of stars and gas, this delicate, floating apparition is cataloged as NGC 7635 -- The Bubble Nebula. In this wide-angle view, the Bubble nebula lies at the center of a larger complex of shocked glowing gas about 11,000 light-years distant in the fair constellation Cassiopeia. NGC 7635 really is an interstellar bubble, blown by winds from the brightest star visible within the bubble's boundary. The bubble's expansion is constrained by the surrounding material. About 10 light-years in diameter, if the Bubble nebula were centered on the Sun, the Sun's nearest stellar neighbor, Alpha Centauri, would also be enclosed. This breathtaking picture is a combination of telescopic digital images made through broad color filters along with a narrow filter intended to transmit only the red light emitted by excited hydrogen atoms.
Stars and the Bubble Nebula
Credit & Copyright: Brian Lula
Seemingly adrift in a cosmic sea of stars and gas, this delicate, floating apparition is cataloged as NGC 7635 -- The Bubble Nebula. In this wide-angle view, the Bubble nebula lies at the center of a larger complex of shocked glowing gas about 11,000 light-years distant in the fair constellation Cassiopeia. NGC 7635 really is an interstellar bubble, blown by winds from the brightest star visible within the bubble's boundary. The bubble's expansion is constrained by the surrounding material. About 10 light-years in diameter, if the Bubble nebula were centered on the Sun, the Sun's nearest stellar neighbor, Alpha Centauri, would also be enclosed. This breathtaking picture is a combination of telescopic digital images made through broad color filters along with a narrow filter intended to transmit only the red light emitted by excited hydrogen atoms.
2003 January 18
Filaments in the Cygnus Loop
Credit: William P. Blair and Ravi Sankrit (Johns Hopkins University), NASA
Subtle and delicate in appearance, these are filaments of shocked interstellar gas -- part of the expanding blast wave from a violent stellar explosion. Recorded in November 1997 with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope, the picture is a closeup of a supernova remnant known as the Cygnus Loop. The nearly edge-on view shows a small portion of the immense shock front moving toward the top of the frame at about 170 kilometers per second while glowing in light emitted by atoms of excited hydrogen gas. Not just another pretty picture, this particular image has provided some dramatic scientific results. In 1999, researchers used it to substantially revise downward widely accepted estimates of distance and age for this classic supernova remnant. Now determined to lie only 1,440 light-years away, the Cygnus Loop is thought to have been expanding for 5 - 10 thousand years.
Filaments in the Cygnus Loop
Credit: William P. Blair and Ravi Sankrit (Johns Hopkins University), NASA
Subtle and delicate in appearance, these are filaments of shocked interstellar gas -- part of the expanding blast wave from a violent stellar explosion. Recorded in November 1997 with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope, the picture is a closeup of a supernova remnant known as the Cygnus Loop. The nearly edge-on view shows a small portion of the immense shock front moving toward the top of the frame at about 170 kilometers per second while glowing in light emitted by atoms of excited hydrogen gas. Not just another pretty picture, this particular image has provided some dramatic scientific results. In 1999, researchers used it to substantially revise downward widely accepted estimates of distance and age for this classic supernova remnant. Now determined to lie only 1,440 light-years away, the Cygnus Loop is thought to have been expanding for 5 - 10 thousand years.
2003 January 19
Fullerenes as Miniature Cosmic Time Capsules
Credit & Copyright: Keith Beardmore (LANL)
Scientists have found, unexpectedly, tiny time capsules from billions of years in the past. The discovery involves small molecules that can apparently become trapped during the formation of large enclosed molecules known as fullerenes, or buckyballs. Luann Becker (UCSB) and collaborators recently found fullerenes in an ancient meteorite that fell to Earth about 30 years ago. Extra-terrestrial fullerenes inside the meteorite survived, and upon inspection, were not empty inside. The small molecules trapped inside are giving a glimpse of what the Solar System was like during its formation. Pictured above is a computer simulation showing a relatively small fullerene (60-atoms of carbon) situated above a hydrogenated silicon surface. How these fullerenes formed, how they survived, where else they can be found, and what else might be found inside these tiny time capsules is developing into an exciting area of research.
Fullerenes as Miniature Cosmic Time Capsules
Credit & Copyright: Keith Beardmore (LANL)
Scientists have found, unexpectedly, tiny time capsules from billions of years in the past. The discovery involves small molecules that can apparently become trapped during the formation of large enclosed molecules known as fullerenes, or buckyballs. Luann Becker (UCSB) and collaborators recently found fullerenes in an ancient meteorite that fell to Earth about 30 years ago. Extra-terrestrial fullerenes inside the meteorite survived, and upon inspection, were not empty inside. The small molecules trapped inside are giving a glimpse of what the Solar System was like during its formation. Pictured above is a computer simulation showing a relatively small fullerene (60-atoms of carbon) situated above a hydrogenated silicon surface. How these fullerenes formed, how they survived, where else they can be found, and what else might be found inside these tiny time capsules is developing into an exciting area of research.
2003 January 20
Io at Sunset
Credit: Galileo Project, JPL, NASA
How tall are mountains on Jupiter's moon Io? One way to find out is to view them at sunset. Tall structures facing the Sun are then better-lit and cast long shadows. The above image highlights Mongibello Mons on the far left, a sharp ridge rising so high it would rank among the highest mountains on Earth. The violently changing surface of Io shows not only classic volcano cinder cones but also many thrust faults where the ground has fractured and created dramatic shear cliffs. The grayscale image was taken two years ago by the robot spacecraft Galileo currently orbiting Jupiter.
Io at Sunset
Credit: Galileo Project, JPL, NASA
How tall are mountains on Jupiter's moon Io? One way to find out is to view them at sunset. Tall structures facing the Sun are then better-lit and cast long shadows. The above image highlights Mongibello Mons on the far left, a sharp ridge rising so high it would rank among the highest mountains on Earth. The violently changing surface of Io shows not only classic volcano cinder cones but also many thrust faults where the ground has fractured and created dramatic shear cliffs. The grayscale image was taken two years ago by the robot spacecraft Galileo currently orbiting Jupiter.
2003 January 21
The Reflecting Dust Clouds of Orion
Credit & Copyright: Daniel Verschatse (Antilhue Obs.)
In the vast Orion Molecular Cloud complex, several bright blue nebulas are particularly apparent. Pictured above are two of the most prominent reflection nebulas - dust clouds lit by the reflecting light of bright embedded stars. The more famous nebula is M78, on the upper right, cataloged over 200 years ago. On the lower left is the lesser known NGC 2071. Astronomers continue to study these reflection nebulas to better understand how interior stars form. The Orion complex lies about 1500 light-years distant, contains the Orion and Horsehead nebulas, and covers much of the constellation of Orion.
The Reflecting Dust Clouds of Orion
Credit & Copyright: Daniel Verschatse (Antilhue Obs.)
In the vast Orion Molecular Cloud complex, several bright blue nebulas are particularly apparent. Pictured above are two of the most prominent reflection nebulas - dust clouds lit by the reflecting light of bright embedded stars. The more famous nebula is M78, on the upper right, cataloged over 200 years ago. On the lower left is the lesser known NGC 2071. Astronomers continue to study these reflection nebulas to better understand how interior stars form. The Orion complex lies about 1500 light-years distant, contains the Orion and Horsehead nebulas, and covers much of the constellation of Orion.
2003 January 22
M11: The Wild Duck Cluster
Credit & Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT
Many stars like our Sun were formed in open clusters. The above pictured open cluster, M11, contains thousands of stars and is just over five thousand light years distant. The stars in this cluster all formed together about 250 million years ago. The bright young stars in M11 appear blue. Open clusters, also called galactic clusters, contain fewer and younger stars than globular clusters. Also unlike globular clusters, open clusters are generally confined to the plane of our Galaxy. M11 is visible with binoculars towards the constellation of Scutum.
M11: The Wild Duck Cluster
Credit & Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT
Many stars like our Sun were formed in open clusters. The above pictured open cluster, M11, contains thousands of stars and is just over five thousand light years distant. The stars in this cluster all formed together about 250 million years ago. The bright young stars in M11 appear blue. Open clusters, also called galactic clusters, contain fewer and younger stars than globular clusters. Also unlike globular clusters, open clusters are generally confined to the plane of our Galaxy. M11 is visible with binoculars towards the constellation of Scutum.
2003 January 23
Launch of the Sun Pillar
Credit & Copyright: Lauri A. Kangas
On January 16, NASA's space shuttle Columbia roared into blue morning skies above Kennedy Space Center on STS-107, the first shuttle mission of 2003. But this is not a picture of that launch! It was taken on the morning of January 16 though, at sunrise, looking eastward toward Lake Ontario from just outside of Caledon, Ontario, Canada. In the picture a sun pillar, sunlight reflecting from ice crystals gently falling through the cold air, seems to shoot above the fiery Sun still low on the horizon. By chance, fog and clouds forming over the relatively warm lake look like billowing smoke from a rocket's exhaust plume and complete the launch illusion. Amateur photographer Lauri Kangas stopped on his way to work to record the eye-catching sun pillar launch.
Launch of the Sun Pillar
Credit & Copyright: Lauri A. Kangas
On January 16, NASA's space shuttle Columbia roared into blue morning skies above Kennedy Space Center on STS-107, the first shuttle mission of 2003. But this is not a picture of that launch! It was taken on the morning of January 16 though, at sunrise, looking eastward toward Lake Ontario from just outside of Caledon, Ontario, Canada. In the picture a sun pillar, sunlight reflecting from ice crystals gently falling through the cold air, seems to shoot above the fiery Sun still low on the horizon. By chance, fog and clouds forming over the relatively warm lake look like billowing smoke from a rocket's exhaust plume and complete the launch illusion. Amateur photographer Lauri Kangas stopped on his way to work to record the eye-catching sun pillar launch.
2003 January 24
Seyfert's Sextet
Credit: J. English (U. Manitoba), C. Palma (PSU), et al., NASA
Known as Seyfert's Sextet, this intriguing group of galaxies lies in the head portion of the split constellation Serpens. The sextet actually contains only four interacting galaxies, though. Near the center of this Hubble Space Telescope picture, the small face-on spiral galaxy lies in the distant background and appears only by chance aligned with the main group. Also, the prominent condensation on the far right is likely not a separate galaxy at all, but a tidal tail of stars flung out by the galaxies' gravitational interactions. About 190 million light-years away, the interacting galaxies are tightly packed into a region around 100,000 light-years across, comparable to the size of our own Milky Way galaxy, making this one of the densest known galaxy groups. Bound by gravity, the close-knit group may coalesce into a single large galaxy over the next few billion years.
Seyfert's Sextet
Credit: J. English (U. Manitoba), C. Palma (PSU), et al., NASA
Known as Seyfert's Sextet, this intriguing group of galaxies lies in the head portion of the split constellation Serpens. The sextet actually contains only four interacting galaxies, though. Near the center of this Hubble Space Telescope picture, the small face-on spiral galaxy lies in the distant background and appears only by chance aligned with the main group. Also, the prominent condensation on the far right is likely not a separate galaxy at all, but a tidal tail of stars flung out by the galaxies' gravitational interactions. About 190 million light-years away, the interacting galaxies are tightly packed into a region around 100,000 light-years across, comparable to the size of our own Milky Way galaxy, making this one of the densest known galaxy groups. Bound by gravity, the close-knit group may coalesce into a single large galaxy over the next few billion years.
2003 January 25
Palomar 13's Last Stand
Credit: M. Siegel & S. Majewski (UVA), C. Gallart (Yale), K. Cudworth (Yerkes), M. Takamiya (Gemini),
Las Campanas Observatory
Globular star cluster Palomar 13 has roamed the halo of our Milky Way Galaxy for the last 12 billion years. The apparently sparse cluster of stars just left of center in this composite color digital image, it is one of the smallest, faintest globular clusters known. (The bright foreground star near bottom is unrelated and creates the spiky imaging artifacts.) Observations spanning forty years indicate that Palomar 13's galactic halo orbit is a highly eccentric one which, every one or two billion years, brings it relatively close to the galactic center. With each close approach to the Milky Way's central regions, gravitational tidal forces strip away the delicately bound cluster stars. In fact, detailed present day studies offer evidence for a dramatic end to this dwindling cluster's tidal tug of war. Palomar 13's latest close approach was only about 70 million years ago. But, when Palomar 13 again approaches the galaxy, it could well turn out to be the cluster's last stand.
Palomar 13's Last Stand
Credit: M. Siegel & S. Majewski (UVA), C. Gallart (Yale), K. Cudworth (Yerkes), M. Takamiya (Gemini),
Las Campanas Observatory
Globular star cluster Palomar 13 has roamed the halo of our Milky Way Galaxy for the last 12 billion years. The apparently sparse cluster of stars just left of center in this composite color digital image, it is one of the smallest, faintest globular clusters known. (The bright foreground star near bottom is unrelated and creates the spiky imaging artifacts.) Observations spanning forty years indicate that Palomar 13's galactic halo orbit is a highly eccentric one which, every one or two billion years, brings it relatively close to the galactic center. With each close approach to the Milky Way's central regions, gravitational tidal forces strip away the delicately bound cluster stars. In fact, detailed present day studies offer evidence for a dramatic end to this dwindling cluster's tidal tug of war. Palomar 13's latest close approach was only about 70 million years ago. But, when Palomar 13 again approaches the galaxy, it could well turn out to be the cluster's last stand.
2003 January 26
The Lyman Alpha Forest
Credit & Copyright: J. Shalf, Y. Zhang (UIUC) et al., GCCC
We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest. Distant quasars appear to be absorbed by many more Lyman-alpha clouds than nearby quasars, indicating a Lyman-alpha thicket early in our universe. The above image depicts one possible computer realization of how Lyman-alpha clouds were distributed at a redshift of 3. Each side of the box measures 30 million light-years across. Much remains unknown about the Lyman-alpha forest, including the real geometry and extent of the clouds, and why there are so many fewer clouds today.
The Lyman Alpha Forest
Credit & Copyright: J. Shalf, Y. Zhang (UIUC) et al., GCCC
We live in a forest. Strewn throughout the universe are "trees" of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar's spectra, together called the Lyman-alpha forest. Distant quasars appear to be absorbed by many more Lyman-alpha clouds than nearby quasars, indicating a Lyman-alpha thicket early in our universe. The above image depicts one possible computer realization of how Lyman-alpha clouds were distributed at a redshift of 3. Each side of the box measures 30 million light-years across. Much remains unknown about the Lyman-alpha forest, including the real geometry and extent of the clouds, and why there are so many fewer clouds today.
2003 January 27
BHR 71: Stars, Clouds, and Jets
Credit & Copyright: J. Alves (ESO), E. Tolstoy (Groningen), R. Fosbury (ST-ECF), & R. Hook (ST-ECF), VLT
What is happening to molecular cloud BHR 71? Quite possible, a binary star system is forming inside. Most stars in our Galaxy are part of binary star systems, but few have ever been seen in formation. Recent observations of dust-darkened Bok Globule BHR 71, however, show evidence for two young stars forming deep in the cloud, likely close enough to form a binary. Isolated BHR 71 spans about one light year and lies only about 600 light years away in the southern sky. The brighter embedded star -- not visible here -- is about 10 times as bright as the Sun and drives the jet that swept out the empty lane. The above four-color image was taken with a Very Large Telescope in Chile.
BHR 71: Stars, Clouds, and Jets
Credit & Copyright: J. Alves (ESO), E. Tolstoy (Groningen), R. Fosbury (ST-ECF), & R. Hook (ST-ECF), VLT
What is happening to molecular cloud BHR 71? Quite possible, a binary star system is forming inside. Most stars in our Galaxy are part of binary star systems, but few have ever been seen in formation. Recent observations of dust-darkened Bok Globule BHR 71, however, show evidence for two young stars forming deep in the cloud, likely close enough to form a binary. Isolated BHR 71 spans about one light year and lies only about 600 light years away in the southern sky. The brighter embedded star -- not visible here -- is about 10 times as bright as the Sun and drives the jet that swept out the empty lane. The above four-color image was taken with a Very Large Telescope in Chile.
2003 January 28
The Lost World of Lake Vida
Credit & Copyright: Thomas Nylen & Andrew Fountain (PSU), NASA, NSF
A lake hidden beneath 19 meters of ice and gravel has been found near the bottom of the world that might contain an ecosystem completely separate from our own. In a modern version of Sir Arthur Conan Doyle's classic book Lost World, scientists are now plotting a mission to drill down into the lake and take out a small part to see what's there. Lake Vida, buried under Antarctic ice for over 2,500 years, is liquid only because of its high salt content. Previously, scientists drilled to within a few meters of the lake and indeed found frozen microbes. Their existence bolsters speculation that similar microorganisms could be found in frozen brine beneath the surface of Mars. If living organisms are found in Lake Vida, they may give an indication that life might even still exist under similar frozen ice-sheets, such as under the larger Lake Vostok, parts of Mars, and even moons of Jupiter such as Europa. Pictured above, a robot meteorological station continues to monitor surface conditions over the ice-sealed lake.
The Lost World of Lake Vida
Credit & Copyright: Thomas Nylen & Andrew Fountain (PSU), NASA, NSF
A lake hidden beneath 19 meters of ice and gravel has been found near the bottom of the world that might contain an ecosystem completely separate from our own. In a modern version of Sir Arthur Conan Doyle's classic book Lost World, scientists are now plotting a mission to drill down into the lake and take out a small part to see what's there. Lake Vida, buried under Antarctic ice for over 2,500 years, is liquid only because of its high salt content. Previously, scientists drilled to within a few meters of the lake and indeed found frozen microbes. Their existence bolsters speculation that similar microorganisms could be found in frozen brine beneath the surface of Mars. If living organisms are found in Lake Vida, they may give an indication that life might even still exist under similar frozen ice-sheets, such as under the larger Lake Vostok, parts of Mars, and even moons of Jupiter such as Europa. Pictured above, a robot meteorological station continues to monitor surface conditions over the ice-sealed lake.
2003 January 29
Orion's Horsehead Nebula
Credit & Copyright: Loke Kun Tan (StarryScapes)
The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the red emission nebula seen above and to the right of center in the above photograph. The bright star on the left is located in the belt of the familiar constellation of Orion. The horse-head feature is dark because it is really an opaque dust cloud which lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will alter its appearance. The emission nebula's red color is caused by electrons recombining with protons to form hydrogen atoms. Also visible in the picture are blue reflection nebulae, which preferentially reflect the blue light from nearby stars.
Orion's Horsehead Nebula
Credit & Copyright: Loke Kun Tan (StarryScapes)
The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the red emission nebula seen above and to the right of center in the above photograph. The bright star on the left is located in the belt of the familiar constellation of Orion. The horse-head feature is dark because it is really an opaque dust cloud which lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will alter its appearance. The emission nebula's red color is caused by electrons recombining with protons to form hydrogen atoms. Also visible in the picture are blue reflection nebulae, which preferentially reflect the blue light from nearby stars.
2003 January 30
Comet Kudo-Fujikawa: Days in the Sun
Credit: SOHO - LASCO Consortium, ESA, NASA
Cruising through the inner Solar System, new Comet Kudo-Fujikawa reached perihelion, its closest approach to the Sun, yesterday, January 29. Passing within 28.4 million kilometers of the Sun, this comet came much closer than innermost planet Mercury basking only 57.9 million kilometers from our parent star. So close to the Sun, comet Kudo-Fujikawa was extremely bright but impossible for earthbound observers to see against the solar glare. Still, the space-based SOHO observatory captured these views of the comet as it neared perihelion by using a coronograph's occulting disk to block the overwhelming sunlight. In the series of images, the size and location of the blocked-out Sun is indicated by white circles, while arrows point to the traveling comet's bright coma and developing tail. Though fading on its outbound journey, Kudo-Fujikawa should soon be visible to southern hemisphere comet-watchers in February's evening skies.
Comet Kudo-Fujikawa: Days in the Sun
Credit: SOHO - LASCO Consortium, ESA, NASA
Cruising through the inner Solar System, new Comet Kudo-Fujikawa reached perihelion, its closest approach to the Sun, yesterday, January 29. Passing within 28.4 million kilometers of the Sun, this comet came much closer than innermost planet Mercury basking only 57.9 million kilometers from our parent star. So close to the Sun, comet Kudo-Fujikawa was extremely bright but impossible for earthbound observers to see against the solar glare. Still, the space-based SOHO observatory captured these views of the comet as it neared perihelion by using a coronograph's occulting disk to block the overwhelming sunlight. In the series of images, the size and location of the blocked-out Sun is indicated by white circles, while arrows point to the traveling comet's bright coma and developing tail. Though fading on its outbound journey, Kudo-Fujikawa should soon be visible to southern hemisphere comet-watchers in February's evening skies.