omnianasa/nasa-apod-metadata huggingface dataset:
Asteroids in the Distance (2005-04-17)
Rocks from space hit Earth every day.  The larger the rock, though, the less often Earth is struck.  Many kilograms of space dust pitter to Earth daily. Larger bits appear initially as a bright meteor.  Baseball-sized rocks and ice-balls streak through our atmosphere daily, most evaporating quickly to nothing.  Significant threats do exist for rocks near 100 meters in diameter, which  strike the Earth roughly every 1000 years.  An object this size could cause significant tsunamis were it to strike an ocean, potentially devastating even distant shores.  A collision with a Massive asteroid, over 1 km across, is more rare, occurring typically millions of years apart, but could have truly global consequences.  Many asteroids remain undiscovered.  In fact, one was discovered in 1998 as the long blue streak in the above archival image taken by the Hubble Space Telescope. In 2002 June, the small 100-meter asteroid 2002 MN was discovered only after it whizzed by the Earth, passing well within the orbit of the Moon.  2002 MN passed closer than any asteroid since 1994 XM1, but not as close as 2004 MN4 will pass in 2029.  A collision with a large asteroid  would not affect Earth's orbit so much as raise dust that would affect Earth's climate.  One likely result is a global extinction of many species of life, possibly dwarfing the ongoing extinction occurring now.
Saturnian Moon and Rings (2005-04-18)
When can a robot produce art?  When it glides past the rings of Saturn. As the robot spacecraft Cassini orbiting Saturn crossed outside the famous photogenic ring plane of the expansive planet, the rings were imaged from the outside, nearly edge on, and in the shadow of Saturn.  From the upper left, ring features include the A ring, the Cassini gap, the B ring, and the darker C ring that includes the Titan gap and a gap yet unnamed.  Last month when the above image was taken, the gliding spacecraft was about one million kilometers from foreground Enceladus, a small Saturnian moon only about 500 kilometers across.  Cassini is scheduled to continue its 70 orbit tour of Saturn over the next three years, sending back images of the gas giant, its rings, and its moons that will be studied for decades to come.
Orion in Infrared (2005-04-19)
Do you recognize the constellation Orion?  This striking but unfamiliar looking picture of the familiar Orion region of the sky was produced using survey data from the now-defunct InfraRed Astronomical Satellite (IRAS).  The above image combines information recorded at three different invisible infrared wavelengths and covers about 30x24 degrees on the sky.  Most of Orion's visually impressive stars don't stand out, but bright Betelgeuse does appear as a small bright purplish dot on the lower left. The bright region on the right contains the Great Nebula in Orion, while the bright region just above the image bottom is the Rosette Nebula.  Surrounding these regions are a jumble of chaotic glowing gas and dark dust jettisoned by stars forming and exploding over millions of years.
Barnard's Loop Around Orion (2005-04-20)
Why is the belt of Orion surrounded by a bubble?  Although glowing like an emission nebula, the origin of the bubble, known as Barnard's Loop, is currently unknown.  Progenitor hypotheses include the winds from bright Orion stars and the supernovas of stars long gone.  Barnard's Loop is too faint to be identified with the unaided eye.  The nebula was discovered only in 1895 by E. E. Barnard on long duration film exposures.  Orion's belt is seen as the three bright stars across the center of the image, the upper two noticeably blue.  Just to the right of the lowest star in Orion's belt is a slight indentation in an emission nebula that, when seen at higher magnification, resolves into the Horsehead Nebula.  To the right of the belt stars is the bright, famous, and photogenic Orion Nebula.
G21.5-0.9: A Supernova's Cosmic Shell (2005-04-21)
The picture is lovely, but this pretty cosmic shell was produced by almost unbelievable violence - created when a star with nearly 20 times the mass of the sun blasted away its outer layers in a spectacular supernova explosion. As the expanding debris cloud swept through surrounding interstellar material, shock waves heated the gas causing the supernova remnant to glow in x-rays. In fact, it is possible that all supernova explosions create similar shells, some brighter than others. Cataloged as G21.5-0.9, this shell supernova remnant is relatively faint, requiring about 150 hours of x-ray data from the orbiting Chandra Observatory to create this false-color image. G21.5-0.9 is about 20,000 light-years distant in the constellation Scutum and measures about 30 light-years across. Based on the remnant's size, astronomers estimate that light from the original stellar explosion first reached Earth several thousand years ago.
Albert Einstein's Miraculous Year (2005-04-22)
In 1905 Albert Einstein had a miraculous year. One hundred years ago, he wrote four papers which revolutionized our understanding of the Universe. The papers outlined; the idea that light could behave as a quantized particle (a photon), an explanation of the thermal motion of atoms and molecules (at a time when atoms themselves were just theories), a theory reconciling motion and the constant speed of light (Special Relativity), and the idea of mass-energy equivalence (E=mc²). Virtually every facet of our modern exploration of the Universe is touched by his now century old insights, along with his later theory of gravity and space-time - General Relativity. In centennial celebration, consider this thoughtful view of a small telescope beside the Einstein Memorial on the grounds of the National Academy of Sciences in Washington DC, USA. The marble platform at the bronze statue's feet is embedded with a map showing the positions of the planets, sun, moon and stars on the memorial's dedication date, 100 years after Einstein's birth in 1879. Albert Einstein died 50 years ago, on April 18, 1955.
Eclipsed Moon in Infrared (2005-04-23)
In September of 1996, the Midcourse Space Experiment (MSX) satellite had a spectacular view of a total lunar eclipse from Earth orbit. SPIRIT III, an on board infrared telescope, was used to repeatedly image the moon during the eclipse. Above is one of the images taken during the 70 minute totality, the Moon completely immersed in the Earth's shadow. Infrared light has wavelengths longer than visible light - humans can not see it but feel it as heat. So, the bright spots correspond to the warm areas on the lunar surface, and dark areas are cooler. The brightest spot below and left of center is the crater Tycho, while the dark region at the upper right is the Mare Crisium. Of course, this Sunday's lunar eclipse will not be a total, or even a partial one. Instead, the Moon will glide through the subtle outer portion of the Earth's shadow in a penumbral eclipse of the Moon.
M16: Stars from Eagle's EGGs (2005-04-24)
Newborn stars are forming in the Eagle Nebula.  This image, taken with the Hubble Space Telescope in 1995, shows evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust.  The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars.  At each pillars' end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense EGGs exposed.  The Eagle Nebula, associated with the open star cluster M16, lies about 7000 light years away.
The Fairy of Eagle Nebula (2005-04-25)
The dust sculptures of the Eagle Nebula are evaporating.  As powerful starlight whittles away these cool cosmic mountains, the statuesque pillars that remain might be imagined as mythical beasts.  Pictured above is one of several striking dust pillars of the Eagle Nebula that might be described as a gigantic alien fairy.   This fairy, however, is ten light years tall and spews radiation much hotter than common fire.  The greater Eagle Nebula, M16, is actually a giant evaporating shell of gas and dust inside of which is a growing cavity filled with a spectacular stellar nursery currently forming an open cluster of stars.  The above image in scientifically re-assigned colors was released as part of the fifteenth anniversary celebration of the launch of the Hubble Space Telescope.
A Martian Dust Devil Passes (2005-04-26)
What goes there across the plains of Mars?  A dust devil.  For the first time, definitive movies of the famous spinning dust towers have been created from ground level.  The robot rover Spirit has now imaged several dust devils from its hillside perch just within the past two months.  Each image in the above sequence was taken about 20 seconds apart.  Inspection of the digitally resized images show the passing dust devil raising Martian dust so thick that it casts a shadow.  The new dust devil movies have been made possible by a new hybrid interaction system where the robot Spirit on Mars takes many images and humans on Earth inspect thumbnails and decide which full resolution images to send back.
The Hercules Cluster of Galaxies (2005-04-27)
These are galaxies of the Hercules Cluster, an archipelago of "island universes" a mere 650 million light-years distant. This cluster is loaded with gas and dust rich, star forming, spiral galaxies but has relatively few elliptical galaxies, which lack gas and dust and the associated newborn stars. Colors in the composite image show the star forming galaxies with a blue tint and ellipticals with a slightly yellowish cast. In this cosmic vista many galaxies seem to be colliding or merging while others seem distorted - clear evidence that cluster galaxies commonly interact. Over time, the galaxy interactions are likely to affect the the content of the cluster itself. Researchers believe that the Hercules Cluster is significantly similar to young galaxy clusters in the distant, early Universe and that exploring galaxy types and their interactions in nearby Hercules will help unravel the threads of galaxy andcluster evolution.
M51: Cosmic Whirlpool (2005-04-28)
Follow the handle of the Big Dipper away from the dipper's bowl, until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you might find this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with well defined spiral structure is also cataloged as NGC 5194. Its spiral arms and dust lanes clearly sweep in front of its companion galaxy (right), NGC 5195. The pair are about 31 million light-years distant and officially lie within the boundaries of the small constellation Canes Venatici. Though M51 looks faint and fuzzy in small, earthbound telescopes, this sharpest ever picture of M51 was made in January 2005 with the Advanced Camera for Surveys on board the Hubble Space Telescope.
Small Moon Epimetheus (2005-04-29)
Small saturnian moon Epimetheus (ep-ee-MEE-thee-us) is at most 116 kilometers across. Its cratered surface and irregular shape are highlighted by dramatic shadows in this composite close-up image from the Cassini spacecraft. However, orbiting 91,000 kilometers above Saturn's cloud tops, Epimetheus is not alone. Similar in size, saturnian moon Janus occupies an orbit separated from Epimetheus' by only about 50 kilometers. The two actually approach each other once every four years, but instead of colliding, the moons deftly exchange orbits and move apart again! In fact, co-orbiting Epimetheus and Janus both consist mostly of porous water ice and could have formed from the breakup of a single parent body. The small moons are also believed to play a role in maintaining the outer edge of Saturn's A ring.
The Moons of Earth (2005-04-30)
While orbiting the planet during their June 1998 mission, the crew of the Space Shuttle Discovery photographed this view of two moons of Earth. Thick storm clouds are visible in the lovely blue planet's nurturing atmosphere and, what was then Earth's largest artificial moon, the spindly Russian Mir Space Station can be seen above the planet's limb. The bright spot to the right of Mir is Earth's very large natural satellite, The Moon. The Mir orbited planet Earth once every 90 minutes about 200 miles above the planet's surface or about 4,000 miles from Earth's center. The Moon orbits once every 28 days at a distance of about 250,000 miles from the center of the Earth.
Planetary Nebula Mz3: The Ant Nebula (2005-05-01)
Why isn't this ant a big sphere?  Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round.  Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round?  Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star  visible above at the nebula's center.  One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star.  A competing hypothesis holds that the central star's own spin and magnetic field are channeling the gas.  Since the central star appears to be so similar to our own Sun, astronomers hope that increased understanding of the history of this giant space ant can provide useful insight into the likely future of our own Sun and Earth.
Methusaleh Outcrop on Mars (2005-05-02)
What is the history of the outcropping of rock called Methuselah?  The unusual rock group is visible on the left of the above image taken by the robot Spirit rover current exploring Mars.  Methuselah was discovered while maneuvering over hilly terrain and shows unusual multiple layering that caught the attention of the rover science team.  Since the above representative color image was taken about three weeks ago, Spirit has moved in to get a closer look.  Also visible in the above image are another rock outcrop dubbed Larry's Lookout on the upper right and a larger Clark Hill in the left background.  On the far right is a more distant peak of the Columbia Hills.
Solar System Rising Over Fire Island (2005-05-03)
If you wait long enough, the entire Solar System will rise before you.  To see such a sight, however, you will need to look in the direction of the ecliptic.  All of the planets and their moons orbit the Sun in nearly the same plane, the ecliptic plane.   From the Earth, this means that each day they will all rise in nearly the same direction - and later set in the opposite direction. Ten years ago, a series of time exposures caught, left to right, the Sun, Venus, the Moon, and Jupiter, all rising in the ecliptic plane behind Fire Island, New York, USA.  Exposures were taken every six minutes and digitally superposed on an image taken from the same location at sunrise.  Smaller members of our Solar System, including most comets and many asteroids, do not always move along the ecliptic plane.  The picturesque Fire Island Lighthouse, visible in the foreground, was built in 1826 and is still in use today.
Cassini Spacecraft Crosses Saturn's Ring Plane (2005-05-04)
If this is Saturn, where are the rings?  When Saturn's "appendages" disappeared in 1612, Galileo did not understand why.   Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear.  This is because Saturn's rings are confined to a plane many times thinner, in proportion, than a razor blade.  In modern times, the robot Cassini spacecraft orbiting Saturn now also crosses Saturn's ring plane.  A series of plane crossing images from late February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro.  Pictured above, digitally cropped and set in representative colors, is the striking result.  Saturn's thin ring plane appears in blue, bands and clouds in Saturn's upper atmosphere appear in gold, and dark shadows of the rings curve across the top of the gas giant planet.  Moons appear as bumps in the rings.
Mira: The Wonderful Star (2005-05-05)
To seventeenth century astronomers, Omicron Ceti or Mira was known as a wonderful star - a star whose brightness could change dramatically in the course of about 11 months. Modern astronomers now recognize an entire class of long period Mira-type variables as cool, pulsating, red giant stars, 700 or so times the diameter of the Sun. Only 420 light-years away, red giant Mira (Mira A, right) itself co-orbits with a companion star, a small white dwarf (Mira B). Mira B is surrounded by a disk of material drawn from the pulsating giant and in such a double star system, the white dwarf star's hot accretion disk is expected to produce some x-rays. But this sharp, false-color image from the Chandra Observatory also captures the cool giant star strongly flaring at x-ray energies, clearly separated from the x-ray emission of its companion's accretion disk. Placing your cursor over the Chandra x-ray image of Mira will reveal an artist's vision of this still wonderful interacting binary star system.
Hybrid Solar Eclipse (2005-05-06)
April's spectacular geocentric celestial event was a rare hybrid eclipse of the Sun - a total or an annular eclipse could be seen depending on the observer's location. For Fred Espenak, aboard a gently swaying ship within the middle of the Moon's shadow track about 2,200 kilometers west of the Galapagos, the eclipse was total, the lunar silhouette exactly covering the bright solar disk for a few brief moments. His camera captured a picture of totality revealing the extensive solar corona and prominences rising above the Sun's edge. But for Stephan Heinsius, near the end of the shadow track at Penonome Airfield, Panama, the Moon's apparent size had shrunk enough to create an annular eclipse, showing a complete annulus of the Sun's bright disk as a dramatic ring of fire.  Pictures from the two locations are compared above. How rare is such a hybrid eclipse? Calculations show that during the 21st century just 3.1% (7 out of 224) of solar eclipses are hybrid while hybrids comprise about 5% of all solar eclipses over the period 2000 BC to AD 4000.
NGC 3314: When Galaxies Overlap (2005-05-07)
NGC 3314 consists of two large spiral galaxies which just happen to almost exactly line-up. The foreground spiral is viewed nearly face-on, its pinwheel shape defined by young bright star clusters. But against the glow of the background galaxy, dark swirling lanes of interstellar dust are also seen to echo the face-on spiral's structure. The dust lanes are surprisingly pervasive, and this remarkable pair of overlapping galaxies is one of a small number of systems in which absorption of visible light can be used to directly explore the distribution of dust in distant spirals. NGC 3314 is about 140 million light-years away in the multi-headed constellation Hydra. This color composite was constructed from Hubble Space Telescope images made in 1999 and 2000.
CMBR Dipole: Speeding Through the Universe (2005-05-08)
Our Earth is not at rest.  The Earth moves around the Sun.  The Sun orbits the center of the Milky Way Galaxy.  The Milky Way Galaxy orbits in the Local Group of Galaxies.  The Local Group falls toward the Virgo Cluster of Galaxies.  But these speeds are less than the speed that all of these objects together move relative to the cosmic microwave background radiation (CMBR).  In the above all-sky map, radiation in the Earth's direction of motion appears blueshifted and hence hotter, while radiation on the opposite side of the sky is redshifted and colder.  The map indicates that the Local Group moves at about 600 kilometers per second relative to this primordial radiation.  This high speed was initially unexpected and its magnitude is still unexplained.  Why are we moving so fast?  What is out there?
Stars, Dust and Nebula in NGC 6559 (2005-05-09)
When stars form, pandemonium reigns.  A textbook case is the star forming region NGC 6559.  Visible above are red glowing emission nebulas of hydrogen, blue reflection nebulas of dust, dark absorption nebulas of dust, and the stars that formed from them.  The first massive stars formed from the dense gas will emit energetic light and winds that erode, fragment, and sculpt their birthplace.  And then they explode.  The resulting morass can be as beautiful as it is complex.  After tens of millions of years, the dust boils away, the gas gets swept away, and all that is left is a naked open cluster of stars.
The First Image of an Extra Solar Planet (2005-05-10)
It's the faint red object, not the bright white one that might be a historic find.  The white object is surely a brown dwarf star.  Quite possibly, however, the red object is the first direct image of a planet beyond our Solar System.  The intriguing possibility was first reported last year, but many astronomers weren't then convinced that the "planet" was not just a background star.   Earlier this year, the 2M1207 star system was imaged twice more in an effort to resolve the issue.  To the delight of the scientific team, the objects kept the same separation, indicating that they are gravitationally bound.  The faint red object 2M1207b is therefore 100 times fainter, intrinsically, than the bright white brown dwarf 2M1207a -- a characteristic well explained by a planet roughly five times the mass of Jupiter.  The discovery - still subject to further confirmation - is considered a step toward the more ambitious goal of imaging Earth-like planets orbiting distant stars.  The above image was taken with the high-resolution adaptive-optic NaCo camera attached to the 8-meter Very Large Telescope Yepun in Chile.
The Sombrero Galaxy in Infrared (2005-05-11)
This floating ring is the size of a galaxy.  In fact, it is part of the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies.  The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light.  The above image shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light.  The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away.  M104 can be seen with a small telescope in the direction of the constellation of Virgo.
Stars, Galaxies, and Comet Tempel 1 (2005-05-12)
Faint comet Tempel 1 sports a fuzzy blue-tinted tail, just right of center in this lovely field of stars. Recorded on May 3rd slowly sweeping through the constellation Virgo, periodic comet Tempel 1 orbits the Sun once every 5.5 years. Also caught in the skyview are two galaxies at the upper left - NGC 4762 and NGC 4754 - both members of the large Virgo Cluster of galaxies. Classified as a lenticular galaxy, NGC 4762 presents an edge-on disk as a narrow gash of light while NGC 4754 is a football-shaped elliptical galaxy. Similar in apparent size, the galaxies and comet make for an intriguing visual comparison, but Tempel 1 is only about 3 light-minutes from planet Earth. The two Virgo cluster galaxies are 50 million light-years away. NASA's Deep Impact spacecraft is scheduled to encounter Tempel 1 on July 4th, launching a probe to impact the comet's nucleus.
When the Moon Was Young (2005-05-13)
Remember when the Moon was young? It was just last Monday. On May 9th, this slender crescent Moon was recorded at a tender age of 34 hours and 18 minutes. Well, OK ... when calculating the lunar age during a lunation or complete cycle of phases - from New Moon to Full Moon and back to New Moon again - the Moon never gets more than around 29.5 days old. Still, a young Moon can be a rewarding sight, even for casual skygazers, though the slim crescent is relatively faint and only easy to see low in the west as the sky grows dark after sunset. Sighting this young Moon last Monday, lucky astronomer Stefan Seip was also treated to a very dramatic telescopic view of an airliner flying in front of the distant sunlit crescent. At a high altitude, the jet's stunning contrails reflect the strongly reddened light of the Sun setting below the western horizon.