omnianasa/nasa-apod-metadata huggingface dataset:
Planets Over Stonehenge (2002-05-09)
Stonehenge, four thousand year old monument to the Sun, provides an appropriate setting for this delightful snapshot of the Sun's children gathering in planet Earth's sky. While the massive stone structure dates from around 2000 B.C., this arrangement of the visible planets was recorded only a few days ago on the evening of May 4th, 2002 A.D. Bright Jupiter stands highest above the horizon at the upper left. A remarkable, almost equilateral triangle formed by Saturn (left), Mars (top), and Venus (right) is placed just above the stones near picture center. Fighting the glow of the setting sun, Mercury can be spotted closest to the horizon, below and right of the planetary triad. Still easy to enjoy for casual sky gazers, this photogenic and slowly shifting planetary grouping will be joined by a young crescent Moon beginning Monday, May 13.
Trailing Planets (2002-05-10)
Tomorrow's picture: Saturnday  < | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >  Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Technical Rep.: Jay Norris. Specific rights apply. A service of: LHEA at NASA/ GSFC & Michigan Tech. U.
Natural Saturn On The Cassini Cruise (2002-05-11)
What could you see approaching Saturn aboard an interplanetary cruise ship? Your view would likely resemble this subtly shaded image of the gorgeous ringed gas giant. Processed by the Hubble Heritage project, the picture intentionally avoids overemphasizing color contrasts and presents a natural looking Saturn with cloud bands, storms, nearly edge-on rings, and the small round shadow of the moon Enceladus near the center of the planet's disk. Of course, seats were not available on the only ship currently enroute, the Cassini spacecraft. Cassini flew by Jupiter at the turn of the millennium and is scheduled to arrive at Saturn in the year 2004. After an extended cruise to a world 1,400 million kilometers from the Sun, Cassini will tour the Saturnian system, conducting a remote, robotic exploration with software and instruments designed by denizens of planet Earth.
At the Edge of the Helix Nebula (2002-05-12)
While exploring the inner edge of the Helix Nebula with the Hubble Space Telescope's Wide Field Planetary Camera 2, astronomers were able to produce this striking image - rich in details of an exotic environment.  This planetary nebula, created near the final phase of a sun-like star's life, is composed of tenuous shells of gas ejected by the hot central star.  The atoms of gas, stripped of electrons by ultraviolet radiation from the central star, radiate light at characteristic energies allowing specific chemical elements to be identified.  In this image, emission from nitrogen is represented as red, hydrogen emission as green, and oxygen as blue.  The inner edge of the Helix Nebula, also known as NGC 7293, is in the direction toward the central star, which is toward the upper right.  Clearly visible near the inner edge are finger shaped cometary knots.
White Rock Fingers on Mars (2002-05-13)
What caused this unusual white rock formation on Mars?  Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate a more mundane origin: volcanic ash.  Studying the exact color of the formation indicated the volcanic origin.  The light material appears to have eroded away from surrounding area, indicating a very low-density substance consistent with the ash hypothesis. The stark contrast between the rocks and the surrounding sand is compounded by the unusual darkness of the sand.  The above picture was taken with the Thermal Emission Imaging System on the Mars Odyssey spacecraft currently orbiting Mars.  The image spans about 10 kilometers inside a much larger crater.
N44C: A Nebular Mystery (2002-05-14)
Why is N44C glowing so strangely?  The star that appears to power the nebula, although young and bright, does not seem hot enough to create some of the colors observed.  A search for a hidden hotter star in X-rays has come up empty.  One hypothesis is that the known central star has a neutron star companion in a very wide orbit.  Hot X-rays might only then be emitted during brief periods when the neutron star nears the known star and crashes through a disk of surrounding gas.  Future observations might tell.  N44C, pictured in the above Hubble Space Telescope image, is an emission nebula in the Large Magellanic Cloud, a neighboring galaxy to our Milky Way Galaxy. Flowing filaments of colorful gas and dark dust far from the brightest region are likely part of the greater N44 complex.  It would take light about 125 years to cross N44C.
Tail Wags of Comet Ikeya-Zhang (2002-05-15)
As Comet Ikeya-Zhang approached the Sun two months ago, it developed a complex blue ion tail.  The tail was composed of ions that boiled off the nucleus and were pushed away from the Sun by the out-flowing fast-moving particles of the solar wind.  Complexity in the tail is created by comet nucleus rotation, variability in the comet surface evaporation rate, and variability of the Sun's magnetic field and solar wind.  The above animation documents how Comet Ikeya-Zhang's tail changed over 30 minutes in ten consecutive 3-minute exposures on March 11.  Comet Ikeya Zhang is now fading as it heads back to the outer Solar System.  It should remain visible through a small telescope for another month.
Double Trouble Solar Bubbles (2002-05-16)
During April and May, attention has been focused on the western evening sky, presenting its spectacle of bright planets and crescent moons shortly after sunset. Meanwhile, the the Sun itself has not been just sinking quietly below the horizon. For example on May 2nd, two enormous clouds of energetic particles blasted away from the solar surface in nearly simultaneous eruptions. Known as coronal mass ejections (CMEs), they appear as large "bubbles" oriented at about 2 o'clock and 8 o'clock in this composite image from cameras onboard the sun-staring SOHO spacecraft. At picture center, an extreme ultraviolet image of the Sun recorded near the time of these eruptions has been superimposed for scale. The blank region surrounding it corresponds to an occulting disk in one of SOHO's coronagraphic cameras. Speeding outward at millions of kilometers per hour, these two CMEs missed our fair planet. But those that do impact Earth's magnetosphere often trigger auroral displays and disruptions.
Gamma-Ray Burst, Supernova Bump (2002-05-17)
On the 21st of November 2001, satellites detected yet another burst of gamma-rays from the cosmos. While this flash of high-energy photons lasted for less than a minute, eager astronomers have been following the fading optical light from the location of the burst source ever since. Seen above in a series of Hubble Space Telescope images recorded from December 4, 2001 to May 5, 2002 (13 through 161 days after the burst), the fading transient lies to the right of a fuzzy, distant galaxy, likely home to the gamma-ray burster. Two constant point-like objects to the left of the galaxy are foreground stars within our own Milky Way. The transient did not not simply fade away, though. Observations from the Hubble, OGLE, and the large Magellan telescope in Chile indicate that it bumped up or brightened again days after the burst in a convincing display characteristic of a supernova - the death explosion of a massive star. These results add to the mounting evidence that at least some of the mysterious cosmic gamma-ray bursts are produced in the violent event which ends the lives of massive stars.
Andromeda Island Universe (2002-05-18)
How far can you see? The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy some two million light-years away. Without a telescope, even this immense spiral galaxy appears as an unremarkable, faint, nebulous cloud in the constellation Andromeda. But a bright yellow nucleus, dark winding dust lanes, gorgeous blue spiral arms and star clusters are recorded in this stunning telescopic digital mosaic of the nearby island universe. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept only 80 years ago. Were these "spiral nebulae" simply outlying components of our own Milky Way Galaxy or were they instead "island universes" -- distant systems of stars comparable to the Milky Way itself? This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observations of M31 in favor of Andromeda, island universe.
Saturn's Moon Tethys (2002-05-19)
Tethys is one of the larger and closer moons of Saturn.  It was visited by both Voyager spacecraft - Voyager 1 in November 1980 and by Voyager 2 in August 1981.  Tethys is now known to be composed almost completely of water ice.  Tethys shows a large impact crater that nearly circles the planet.  That the impact that caused this crater did not disrupt the moon is taken as evidence that Tethys was not completely frozen in its past.  Two smaller moons, Telesto and Calypso, orbit Saturn just ahead of and behind Tethys.  Giovanni Cassini discovered Tethys in 1684.  In 1997, NASA launched a spacecraft named Cassini to Saturn that will arrive in 2004.
East of the Lagoon Nebula (2002-05-20)
To the east of the Lagoon Nebula is a star field rich in diversity.  On the lower left are clouds rich in dark dust that hide background stars and young star systems still forming.  Dark clouds include LDN 227 on the left and IC 1275 on the right, with a bright star near its tip.  On the upper right are clouds rich in hot glowing gas, including part of the emission nebula NGC 6559.  On the right, between the two regions, is a nebula reflecting light from a group of massive blue stars.  The NGC 6559 complex pictured above spans about 3 light years and likely has a common history with the Lagoon Nebula.  The complex lies about 5000 light-years away toward the constellation of Sagittarius.
The Galactic Center Radio Arc (2002-05-21)
What causes this unusual structure near the center of our Galaxy? The long parallel rays slanting across the top of the above radio image are known collectively as the Galactic Center Radio Arc and jut straight out from the Galactic plane.  The Radio Arc is connected to the Galactic center by strange curving filaments known as the Arches.  The bright radio structure at the bottom right likely surrounds a black hole at the Galactic center and is known as Sagittarius A*.  One origin hypothesis holds that the Radio Arc and the Arches have their geometry because they contain hot plasma flowing along lines of constant magnetic field.  Recent images from the Chandra X-ray Observatory appear to show this plasma colliding with a nearby cloud of cold gas.
Moon and Planets by the Eiffel Tower (2002-05-22)
Tomorrow's picture: the color of x-rays  < | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >  Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Technical Rep.: Jay Norris. Specific rights apply. A service of: LHEA at NASA/ GSFC & Michigan Tech. U.
N132D and the Color of X-Rays (2002-05-23)
Supernova remnant N132D shows off complex structures in this sharp, color x-ray image. Still, overall this cosmic debris from a massive star's explosive death has a strikingly simple horseshoe shape. While N132D lies 180,000 light-years distant in the Large Magellanic Cloud, the expanding remnant appears here about 80 light-years across. Light from the supernova blast which created it would have reached planet Earth about 3,000 years ago. Observed by the orbiting Chandra Observatory, N132D still glows in x-rays, its shocked gas heated to millions of degrees Celsius. Since x-rays are invisible, the Chandra x-ray image data are represented in this picture by assigning visible colors to x-rays with different energies. Low energy x-rays are shown as red, medium energy as green, and high energy as blue colors. These color choices make a pleasing picture and they also show the x-rays in the same energy order as visible light photons, which range from low to high energies as red, green, and blue.
Love and War by Moonlight (2002-05-24)
Venus, named for the Roman goddess of love, and Mars, the war god's namesake, approach each other by moonlight in this lovely sky view recorded on May 14th from Dunkirk, Maryland, USA. The four second time exposure made in twilight with a digital camera also records earthshine illuminating the otherwise dark surface of the young crescent Moon. Venus shines as the third brightest object in Earth's sky, after the Sun and the Moon itself, and has been appearing as the brilliant evening star in the pantheon of planets arrayed in the west during April and May. Here, Venus' light is so intense that it produces a noticeable spike in the sensitive camera's image. Much fainter Mars is lower in the picture, caught between tree limbs swaying in a gentle evening breeze. By early June, Mars will be harder to spot as it wanders toward the horizon, but Venus and father Jupiter will draw closer together, presenting a spectacular pair of bright planets in the west.
A String Of Pearls (2002-05-25)
Comet Shoemaker-Levy 9, named after its co-discoverers, was often referred to as the "string of pearls" comet. It is famous for its suggestive appearance as well as its collision with the planet Jupiter! The comet's original single nucleus was torn to pieces by Jupiter's strong gravity during a close encounter with the solar system's largest planet in 1992. The pieces are seen (scroll right) in this composite of Hubble Space Telescope images to be "pearls" strung out along the comet's orbital path. In July of 1994 these pieces collided with Jupiter in a rare and spectacular series of events.
The Pipe Dark Nebula (2002-05-26)
The dark nebula predominant at the lower left of the above photograph is known as the Pipe Nebula.  The dark clouds, suggestively shaped like smoke rising from a pipe, are caused by absorption of background starlight by dust.  These dust clouds can be traced all the way to the Rho Ophiuchi nebular clouds on the right.  The brightest star in the field is Antares. Many types of nebula are highlighted here: the red are emission nebula, the blue are reflection nebula, and the dark are absorption nebula. This picture has been digitally enhanced.
Antarctic Ice Shelf Vista (2002-05-27)
It's all gone but the mountains.  Most of the sprawling landscape of ice that lies between the mountains visible above has now disintegrated.  The above picture was taken in Antarctica from the top of Grey Nunatak, one of three Seal Nunatak mountains that border the Larsen B Ice-Shelf.  The other two Nunataks are visible in the picture taken in 1994.  Over the past several years large chunks of the 200-meter thick Larsen B Ice-Shelf have been breaking off and disintegrating.  The cause is thought to be related to the local high temperatures of recent years and, possibly, global warming.  Over the past few years, the area that has disintegrated is roughly the size of Luxembourg.  As ice-shelves break up, they unblock other ice sheets that fall onto the ocean, raising sea levels everywhere.  Scientists are watching the much-larger Ross Ice Shelf, which, if it collapses, could cause global sea levels to rise five meters.
The Very Large Array of Radio Telescopes (2002-05-28)
The most photogenic array of radio telescopes in the world has also been one of the most productive.  Each of the 27 radio telescopes in the Very Large Array (VLA) is the size of a house and can be moved on train tracks.  The above pictured VLA, celebrating its twenty-second year of operation, is situated in New Mexico, USA. The VLA has been used to discover water on planet Mercury, radio-bright coronae around ordinary stars, micro-quasars in our Galaxy, gravitationally-induced Einstein rings around distant galaxies, and radio counterparts to cosmologically distant gamma-ray bursts.  The vast size of the VLA has allowed astronomers to study the details of super-fast cosmic jets, and even map the center of our Galaxy.  An upgrade of the VLA is being planned.
Cosmic Ripples Implicate Dark Universe (2002-05-29)
What may appear fuzzy to some makes things crystal clear to others.  The cosmic microwave background radiation emanating from the universe could only have the above fuzzy pattern if it contained clear amounts of dark matter and dark energy.  The conclusion, based on a detailed analysis of the temperature and spacing of the bumps, was a surprise to those who felt that previous evidence for such a strange universe, based on observations of distant supernovae, was somehow inaccurate.  The measurements were made with a novel group of microwave telescopes in Tenerife, Spain called the Very Small Array.  The bumps appearing above are some of the oldest objects ever seen.
Orion Nebulosities (2002-05-30)
Tomorrow's picture: in a canyon on Mars  < | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >  Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Technical Rep.: Jay Norris. Specific rights apply. A service of: LHEA at NASA/ GSFC & Michigan Tech. U.
In Chandor Chasma on Mars (2002-05-31)
Scroll right and dive into a spectacular canyon on Mars. This daytime infrared view, recently recorded by the THEMIS camera on board the orbiting Mars Odyssey spacecraft, covers a 30 by 175 kilometer swath running along the canyon floor. The north (left) end of the scene is poised at the edge of Candor Chasma, part of the great Valles Marineris canyon system. In all about 4,000 kilometers long and up to 6 kilometers deep, Valles Marineris is roughly five times the size of the Grand Canyon on planet Earth. The THEMIS camera data was recorded in three separate infrared bands and combined to make this striking false-color image. Resulting color differences along this intricate section of martian terrain are attributed to differences in mineralogy, the chemical makeup and structure of the rocks, sediments and surface dust.
NGC 2266: Old Cluster in the New General Catalog (2002-06-01)
The New General Catalog of star clusters and nebulae really isn't so new. In fact, it was published in 1888 - an attempt by J. L. E. Dreyer to consolidate the work of astronomers William, Caroline, and John Herschel along with others into a useful single, complete catalog of astronomical discoveries and measurements. Dreyer's work was successful and is still important today as this famous catalog continues to lend its "NGC" to bright clusters, galaxies, and nebulae. Take for example this star cluster known as NGC 2266 (item number 2,266 in the NGC compilation). It lies about 10,000 light-years distant in the constellation Gemini and represents an open or galactic cluster. With an age of about 1 billion years, NGC 2266 is old for a galactic cluster. Its evolved red giant stars are readily apparent in this gorgeous three-color image.
Cracks and Ridges on Europa (2002-06-02)
Which way to the interstate?  What appears to be a caricature of a complex highway system on Earth is actually a system of ridges and cracks on the icy surface of Jupiter's moon Europa.  The distance between parallel ridges in the above photograph is typically about 1 kilometer.  The complexity of the cracks and ridges tell a story of Europa's past that is mostly undecipherable -- planetary geologists try to understand just the general origin of the overall features. One noteworthy feature is the overall white sheen, possibly indicating the presence of frost.  Another is the dark centers between parallel ridges, which might indicate that dirty water from an underground ocean recently welled up in the cracks and froze.  Recent research indicates that enough carbon exists to support an underwater biosphere, but that Europa's ice crust may be over three kilometers thick in some places.
Galaxy NGC 4388 Expels Huge Gas Cloud (2002-06-03)
Why are huge clouds of gas billowing from spiral galaxy NGC 4388?  The extent of the gas clouds, over 100,000 light-years, was unexpected before the Subaru Telescope took the above image.  NGC 4388 has a bright energetic nucleus and so is classified as an active galaxy.  The spiral, relatively close by at 60 million light years, is a member of the nearest major cluster of galaxies: the Virgo Cluster.  One hypothesis holds that the gas was stripped away as NGC 4388 made its way through the  intergalactic medium of the Virgo Cluster. A competing hypothesis holds that the gas is all that remains of a smaller galaxy that was gravitationally deconstructed by the larger NGC 4388.  Further observations may better determine NGC 4388's past and likely contribute to a better understanding of how galaxies evolve inside massive clusters.
A Martian Metamorphosis (2002-06-04)
Is it an Escher, or Mars?  Three different types of surfaces visible in the North Polar Cap of Mars morph into each other in a way perhaps reminiscent of the works of M. C. Escher.  On the far left dark sand covers the ground, while the center shows a transition to a dune field.  On the far right a transition is made to a much lighter surface, likely containing a larger amount of ice.  Shadows indicate that lighter material holds the higher ground, with some steep cliffs on the divide.  Dune shapes indicate that wind typically blows toward the upper left.  Mars Global Surveyor, one of two robot spacecraft currently orbiting Mars, took the above image in early 2001.  Recent images from the other orbiter, Mars Odyssey, have bolstered the hypothesis that a significant amount of water-ice lies beneath the surface near the Martian South Pole.
NGC 3621: Far Beyond the Local Group (2002-06-05)
Far beyond the local group of galaxies lies NGC 3621, some 22 million light-years away. Found in the serpentine southern constellation Hydra, the loose spiral arms of this gorgeous island universe are loaded with luminous young star clusters and dark dust lanes. Still, for earthbound astronomers NGC 3621 is not just another pretty face-on spiral galaxy. Some of its brighter stars have been used as standard candles to establish important estimates of extragalactic distances and the scale of the Universe. This color picture was constructed from astronomical image data recorded with the Very Large Telescope Antu, at Paranal Observatory in Chile.  At the original resolution, individual, hot supergiant stars can be identified and studied across NGC 3621.
Cone Nebula Infrared Close-Up (2002-06-06)
After astronauts repaired NICMOS - the Near Infrared Camera and Multi-Object Spectrometer - during the latest Hubble Space Telescope servicing mission, astronomers were quick to turn the sophisticated instrument on the photogenic stellar nursery known as the Cone Nebula. This remarkable NICMOS close-up of the Cone Nebula dramatically confirms that the Hubble's infrared vision has been restored. Gas and dust clouds at the blunted tip of the cone-shaped star-forming region are seen here in false-color covering an area about half a light-year across. Toward the left hand side of the picture, the four bright stars with diffraction spikes are also present in visible light images and are in front of the Cone Nebula, itself 2,500 light-years away. But the fainter stars to their right are embedded in or behind the nebula's obscuring dust clouds and are revealed only in this penetrating infrared view.