omnianasa/nasa-apod-metadata huggingface dataset:
Saturn: Lord of the Rings (2002-02-15)
Born on today's date in 1564, Galileo used a telescope to explore the Solar System. In 1610, he became the first to be amazed by Saturn's rings. After nearly 400 years, Saturn's magnificent rings still offer one of the most stunning astronomical sights. Uniquely bright compared to the rings of the other gas giants, Saturn's ring system is around 250,000 kilometers wide but in places only a few tens of meters thick. Modern astronomers believe the rings are perhaps only a hundred million years young. But accumulating dust and dynamically interacting with Saturn's moons, the rings may eventually darken and sag toward the gas giant, losing their lustre over the next few hundred million years. Since Galileo, astronomers have subjected the entrancing rings to intense scrutiny to unlock their secrets. Still mesmerized, some will take advantage of next week's (February 20th) favorable lunar occultation of Saturn to search for evidence of ring material outside the well known boundaries of the ring system. The presence of such a "lost" ring of Saturn was first hinted at in reports dating back to the early 20th century.
Miranda, Chevron, and Alonso (2002-02-16)
Miranda is a bizarre world which surely had a tempestuous past. The innermost of the larger Uranian moons, Miranda is almost 300 miles in diameter and was discovered on today's date in 1948 by American planetary astronomer Gerard Kuiper. Examined very closely by the Voyager 2 spacecraft in 1986, this dark and distant world turned out to be quite a surprise. Miranda was found to display a unique, bewildering variety of terrain leading some to suggest that it has been fractured up to 5 times during its evolution. Along with the famous "chevron" feature, the bright V-shaped area just above center, this composite of the highest resolution images of Miranda shows wild juxtapositions of ridges and valleys, older cratered and younger smooth surfaces, and shadowy canyons perhaps 12 miles deep.  The large crater (below center) is the 15 mile wide crater Alonso.
The Local Bubble and the Galactic Neighborhood (2002-02-17)
What surrounds the Sun in this neck of the Milky Way Galaxy?  Our current best guess is depicted in the above map of the surrounding 1500 light years constructed from various observations and deductions.  Currently, the Sun is passing through a Local Interstellar Cloud (LIC), shown in violet, which is flowing away from the Scorpius-Centaurus Association of young stars.  The LIC resides in a low-density hole in the interstellar medium (ISM) called the Local Bubble, shown in black.  Nearby, high-density molecular clouds including the Aquila Rift surround star forming regions, each shown in orange.  The Gum Nebula, shown in green, is a region of hot ionized hydrogen gas.  Inside the Gum Nebula is the Vela Supernova Remnant, shown in pink, which is expanding to create fragmented shells of material like the LIC.  Future observations should help astronomers discern more about the local Galactic Neighborhood and how it might have affected Earth's past climate.
A Radio Vista of Cygnus (2002-02-18)
Shells of ancient supernovas, cocoons surrounding newborn stars, and specks from  distant quasars highlight this tremendous vista toward the constellation of Cygnus.  The representative color image covers about 10 degrees across on the sky but is only a small part of the Canadian Galactic Plane Survey in radio light.  Diffuse bands of ionized gas flow though a dominating region of star formation, located about 6000 light-years away.  Two prominent supernova shells visible include the brown globule on the lower left and the white bumpy sphere on the upper right.  To the left of the brown globule is the entire North America Nebula.  Prominent stellar cocoons are visible throughout the image as bright white knots.  Some of these stars will likely generate future supernova shells.  Far in the distance, visible here as only red dots, quasars glow.
Water-Ice Imaged in Martian Polar Cap (2002-02-19)
Does water exist today on Mars?  Yes, although the only place on Mars known to have water is the North Polar Cap, and that water is frozen.  Views of this potentially life-enabling water-ice are usually obscured -- in the winter by darkness and in the summer by clouds.  Last April, however, the orbiting Mars Global Surveyor spacecraft was able to get a good glimpse of the water-bearing cap just before Martian spring.  Low, dark layers in the above image are thought to contain a large amount of sand, while high, light layers likely contain higher amounts of water-ice.  The image spans an area about 5 kilometers across.
Oddities of Star Cluster NGC 6397 (2002-02-20)
One of these stars is blinking.  This star, a member of globular cluster NGC 6397, is noteworthy not just because it blinks, but because it blinks so fast and because its companion star is so atypical.  Speculation holds that this might be a neutron star spun up to a rate of 274 rotations each second by the bloated red star it orbits.  Matter gravitationally pulled from the bloated star likely orbits the millisecond pulsar, making it spin faster when it crashes onto the surface.  The odd system might have resulted when the neutron star captured a normal star after a near collision near the globular cluster's dense center.  Other collisions near the center of NGC 6397 are thought to have produced other oddities -- blue straggler stars.  The Hubble Space Telescope took the above image of the colorful globular cluster.
Comet Ikeya-Zhang (2002-02-21)
Comet Ikeya-Zhang is presently heading north in planet Earth's sky, framed by stars of the constellation Cetus. The comet was discovered as a faint, telescopic object near the western horizon on the evening of February 1st independently by Kaoru Ikeya of Shizuoka prefecture, Japan, Daqing Zhang in Henan province, China, and later by observer Paulo Raymundo of Salvador, Brazil. But Ikeya-Zhang is expected to brighten significantly and in March and April could become visible to the unaided eye. This picture, taken near Tucson, Arizona, USA on the evening of February 9th, covers a field a bit less than the width of the full moon showing the comet's condensed coma and narrow, developing tail. Ikeya-Zhang should pass closest to the Sun (perihelion) on March 18 at a point roughly midway between the orbits of Mercury and Venus. Based on preliminary calculations of this comet's orbit, Ikeya-Zhang is suspected of being a periodic comet, returning to the inner Solar System every 500 years or so. In fact, it is speculated that Ikeya-Zhang may be directly connected with a historic bright comet seen in 1532.
Saturn at the Lunar Limb (2002-02-22)
Gliding through the sky on Wednesday evening, February 20th, a first quarter Moon seemed to run over bright planet Saturn as viewed from much of North America. In this sharp sequence of telescopic digital images from the Powell Observatory near Louisburg, Kansas, USA, Saturn is seen reappearing from behind the bright lunar limb over a period of about 2 minutes. The ringed planet emerges above the dark, smooth lunar Mare Crisium (Sea of Crises). This lunar occultation was widely anticipated in part because the ringed planet and the brilliant Moon are both spectacular celestial sights. Now, European sky gazers will have their turn as the Moon occults the Solar System's largest planet, Jupiter in early morning hours on Saturday, February 23rd.
Shocked by Supernova 1987A (2002-02-23)
Fifteen years ago today, the brightest supernova of modern times was sighted. Over time, astronomers have watched and waited for the expanding debris from this tremendous stellar explosion to crash into previously expelled material.  A clear result of such a collision is demonstrated above in two frames recorded by the Hubble Space Telescope in 1994 (left) and 1997(right). While the central concentration of stellar debris has clearly evolved over this period, the yellow spot on the ring in the righthand picture announces the collision of an outward moving blast wave with the pre-existing, light-year wide ring.  The collision is occurring at speeds near 60 million kilometers per hour and shock-heats the ring material causing it to glow.  Astronomers are hopeful that such collisions will illuminate the interesting past of SN 1987A, and perhaps provide more clues about the origin of the mysterious rings.
Isaac Newton Explains the Solar System (2002-02-24)
Sir Isaac Newton changed the world.  Born in 1642, Newton was only an above-average student.  But he went home from Cambridge one summer in 1665, thought a lot about the physical nature of the world, and came back two years later with a revolutionary understanding of mathematics, gravitation, and optics.  A Professor of his, upon understanding what Newton had done, resigned his own position at Cambridge so Newton could have it.  Newton's calculus provided a new mathematical framework for the rapid solution of whole classes of physical problems.  Newton's law of gravitation explained in one simple formula how apples fall and planets move.  Newton's insights proved to be so overwhelmingly powerful he was the first scientist ever knighted.
Crescent Europa (2002-02-25)
Tomorrow's picture: Plasma Jets  < | 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.
Jets from Radio Galaxy 3C296 (2002-02-26)
Jets of streaming plasma expelled by the central black hole of a massive elliptical galaxy likely light up this composite image of 3C296.  The jets emanating from NGC 5532 and are nearly a million light years long.  Exactly how the central black hole expels the infalling matter is still unknown.  After clearing the galaxy, however, the jets inflate large radio bubbles that could glow for millions of years.  If excited by a passing front, radio bubbles can even light up again after a billion years.  Visible light is depicted in the above image in blue, while radio waves are shown in red.  The radio map was created with the Very Large Array of radio telescopes.
A Cloud Shadow Sunrise (2002-02-27)
What could cause a ray of dark?  Such a ray was caught in spectacular fashion above the Florida Everglades two years ago.  The cause is something surprisingly familiar: a shadow.  The gold-tinged cloud near the horizon blocks sunlight from reflecting off air behind the cloud, making that column of air appear unusually dark.  Cloud shadows can be thought of the inverse of the more commonly highlighted crepuscular rays, where sunlight pours though cloud holes.  Another seemingly opposite phenomenon, a sun pillar, involves small ice crystals floating high in the atmosphere.
ESO 184-G82: Supernova - Gamma Ray Burst Connection (2002-02-28)
Modern astronomers keep a long list of things that go bump in the night. Near the top are supernovae - the death explosions of massive stars, and gamma-ray bursts - the most powerful explosions seen across the Universe. Intriguingly, the galaxy in the above Hubble Space Telescope image may have been host to both a supernova and a gamma-ray burst which were one and the same event. ESO 184-G82 is a spiral galaxy with a prominent central bar and loose spiral arms dotted with bright star-forming regions. The inset shows an expanded view of one of the star-forming regions, about 300 light-years across. Indicated is the location of an extraordinarily powerful supernova explosion whose light first reached planet Earth on April 25, 1998. That location and date also correspond to the detection of an unusual gamma-ray burst, which may be representative of a peculiar class of these cosmic high-energy flashes. So far, this combination is unique and makes barred spiral ESO 184-G82, at a distance of only 100 million light-years, the closest known gamma-ray burst host galaxy.
Jupiter's Great X-Ray Spot (2002-03-01)
The Solar System's largest planet, gas giant Jupiter, is famous for its swirling Great Red Spot. In the right hand panel above, the familiar giant planet with storm system and cloud bands is shown in an optical image from the passing Cassini spacecraft. In the left hand panel, a false-color image from the orbiting Chandra Observatory presents a corresponding x-ray view of Jupiter. The Chandra image shows clearly, for the first time, x-ray spots and auroral x-ray emission from the poles. The x-ray spot dominating the emission from Jupiter's north pole (top) is perhaps as surprising for astronomers today as the Great Red Spot once was. Confounding previous theories, the x-ray spot is too far north to be associated with heavy electrically charged particles from the vicinity of volcanic moon Io. Chandra data also show that the spot's x-ray emission mysteriously pulsates over a period of about 45 minutes.
M27: Not A Comet (2002-03-02)
While searching the skies above 18th century France for comets, astronomer Charles Messier diligently recorded this object as number 27 on his list of things which are definitely not comets. So what is it? Well, 20th century astronomers would classify it as a Planetary Nebula ... but it's not a planet either, even though it may appear round and planet-like in a small telescope. Messier 27 (M27) is now known to be an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible ultraviolet light. Known by the popular name of the Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is about 1,200 light-years away in the constellation Vulpecula. This gorgeous synthetic color picture of M27 was produced during testing of one of the European Southern Observatory's Very Large Telescopes.
The Regolith of Asteroid Eros (2002-03-03)
Tomorrow's picture: 5,000 horsepower  < | 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.
The Shuttle Crawler Transporter (2002-03-04)
NASA's Crawler-Transporters are the largest tracked vehicles in existence.  Although the crawlers pack over 5,000 horsepower, their top speed is less than two kilometers per hour when fully loaded.  Eleven people are needed to drive a single crawler.  Diesel fuel mileage is about 350 liters per kilometer (less than 0.007 miles per gallon).  The crawler's function is to move NASA's space shuttles -- complete with launch platforms -- from the Assembly Building to the Launch Pad at Kennedy Space Center in Florida, USA.  Two of these massive machines have operated since the Apollo era and have now crawled over 4,000 kilometers, all the while keeping their contents perfectly upright. In this picture a crawler transports the shuttle Columbia to the pad prior to its March 1st launch on the latest Hubble Space Telelescope Servicing Mission.
Earth in True Color (2002-03-05)
Here are the true colors of planet Earth.  Blue oceans dominate our world, while areas of green forest, brown mountains, tan desert, and white ice are also prominent.  Oceans appear blue not only because water itself is blue but also because seawater frequently scatters light from a blue sky.  Forests appear green because they contain chlorophyll, a pigment that preferentially absorbs red light.  The above image is a composite generated predominantly with data from Moderate Resolution Imaging Spectroradiometer (MODIS), an instrument mounted on the Terra satellite that has orbited Earth since 1999 December.  Sub-areas were imaged only when experiencing cloud-free daylight when it occurred from June through September 2001.  The Earth looks much different at night.
Simulated Galaxy Cluster View (2002-03-06)
Stunningly detailed, this picture is a computer simulated view of a cluster of galaxies in the distant cosmos. A large, elliptical galaxy dominates this hypothetical cluster's central region surrounded by a swarm of member galaxies. Other galaxies which lie far behind the cluster are seen as numerous visible concentric arcs - lensed by the enormous gravitational field dominated by dark matter within the cluster itself. Such magnificent images are expected to be achieved by the Advanced Camera for Surveys (ACS), one of the upgrades being installed on the Hubble Space Telescope during the ongoing servicing mission. Compared to Hubble's workhorse Wide Field Planetary Camera 2 (WFPC2), whose achievements include the current deep field views of the Universe, the new technology ACS will be twice as sharp an imager with twice the field of view and five times the sensitivity.  Along with extended views of the distant cosmos, enthusiastic astronomers also plan to use the ACS to monitor our own Solar System and to search for planets orbiting stars beyond the Sun.
Comet Ikeya-Zhang Brightens (2002-03-07)
In the last week, Comet Ikeya-Zhang has become bright enough to be just visible to the unaided eye. Based on its present activity, observers are optimistic that Ikeya-Zhang will become substantially brighter. This composite color image from March 3rd, captured with a wide-field telescope, shows this active comet's bright, condensed coma and a delightful array of subtle structures in its developing tail. The bluish tail stretches for 5 degrees or so against a background of stars in the constellation Pisces. In the coming days look for the comet hanging low in the western evening sky (below a bright yellowish Mars), eventually becoming difficult to see in the March twilight. But after April begins, Ikeya-Zhang will become a predawn object climbing higher into the morning sky as the month progresses. Cataloged as comet C/2002 C1, improved orbit determinations now make it seem very likely that Comet Ikeya-Zhang has been around here before. Refined calculations indicate this comet's last trip through the inner Solar System was 341 years ago, in 1661, when it was recorded as a bright comet.
Columbia Dawn (2002-03-08)
Trailing a thick column of exhaust, the Space Shuttle Columbia blasted into the twilight morning sky on March 1, its thundering rockets briefly flooding a cloud bank with the light of a false dawn. The event marked the start of the ongoing eleven day mission to upgrade the Hubble Space Telescope. Hubble's upgrades include the installation of new solar arrays and a new camera. Columbia's crew is scheduled to complete the work today in the last of five space walks. Columbia's launch also marks the first flight of the oldest operating space shuttle after receiving extensive upgrades itself, designed to increase its capabilities for missions to low Earth orbit. The shuttle landing is expected at Kennedy Space Center on March 12.
A Quasar Portrait Gallery (2002-03-09)
Quasars (QUASi-stellAR objects) lie near the edge of the observable Universe. Discovered in 1963, astronomers were astounded that such objects could be visible across billions of light-years, as this implies they must emit prodigious amounts of energy. Where does the energy come from? Many believe the quasar's central engine is a giant black hole fueled by tremendous amounts of infalling gas, dust, and stars. This gallery of quasar portraits from the Hubble Space Telescope offers a look at their local neighborhoods: the quasars themselves appear as the bright star-like objects with diffraction spikes. The images in the center and right hand columns reveal quasars associated with disrupted colliding and merging galaxies which should provide plenty of debris to feed a hungry black hole.
A Southern Sky View (2002-03-10)
On 1996 March 22, a Galaxy and a comet shared the southern sky.  They were captured together, from horizon to horizon, in the night sky above Loomberah, New South Wales, Australia by astronomer Gordon Garradd. Garradd used a home made all-sky camera with a fisheye lens, resulting in a circular 200 degree field of view.  This gorgeous sky view was dominated by the luminous band of our Milky Way Galaxy cut by dramatic, dark interstellar dust clouds.  Along with the bright stars of our Galaxy, the Large Magellanic Cloud is visible at the lower left.  That night sky was also graced by the long, lovely, bluish tail of Comet Hyakutake, which can be seen toward the top of the image, near the bright star Arcturus.  Bright city lights from nearby Tamworth glow along the Northwestern horizon.
The 100-Meter Green Bank Radio Telescope (2002-03-11)
The largest single-dish fully steerable radio telescope began operation in 2000 August in Green Bank, West Virginia, USA.  Dedicated as the Robert C. Byrd Green Bank Telescope, the device weighs over 30 times more than the Statue of Liberty, and yet can point anywhere in the sky more precisely than one thousandth of a degree.  The main dish is so large that it could house a football game, allowing it to hear even the faint murmurs of quasars located across the universe.  Anyone can propose to use the Green Bank Telescope, although formal proposals are reviewed competitively.  The Green Bank Telescope's large size and innovative design are allowing it to investigate radio waves emitted from comets, planets, pulsars, distant galaxies, and the distant early universe.
Atete Corona on Venus (2002-03-12)
What could cause a huge cylindrical mountain to rise from the surface of Venus?  Such features that occur on Venus are known as coronas.  Pictured above in the foreground is 500-kilometer wide Atete Corona found in a region of Venus known as the Galindo.  The image was created by combining multiple radar maps of the region to form a computer-generated three-dimensional perspective.  The series of dark rectangles that crosses the image from top to bottom were created by the imaging procedure and are not real. The origin of massive coronas remains a mystery although speculation holds they result from some form of volcanism.  Studying Venusian coronas help scientists better understand the inner structure of both Venus and Earth.
LL Orionis: When Cosmic Winds Collide (2002-03-13)
This arcing, graceful structure is actually a bow shock about half a light-year across, created as the wind from young star LL Orionis collides with the Orion Nebula flow. Adrift in Orion's stellar nursery and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind from our own middle-aged sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave of a boat moving through water or a plane traveling at supersonic speed. The slower gas is flowing away from the Orion Nebula's hot central star cluster, the Trapezium, located off the lower right hand edge of the picture. In three dimensions, LL Ori's wrap-around shock front is shaped like a bowl that appears brightest when viewed along the "bottom" edge. The complex stellar nursery in Orion shows a myriad of similar fluid shapes associated with star formation, including the bow shock surrounding a faint star at the upper right. Part of a mosaic covering the Great Nebula in Orion, this composite color image was recorded in 1995 by the Hubble Space Telescope.
SM3B: Mission to Hubble (2002-03-14)
Tomorrow's picture: Neutron 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.