omnianasa/nasa-apod-metadata huggingface dataset:
Ash and Lightning Above an Icelandic Volcano (2010-04-19)
Why did the recent volcanic eruption in Iceland create so much ash? Although the large ash plume was not unparalleled in its abundance, its location was particularly noticeable because it drifted across such well populated areas. The Eyjafjallaj�kull volcano in southern Iceland began erupting on March 20, with a second eruption starting under the center of a small glacier on April 14. Neither eruption was unusually powerful.  The second eruption, however, melted a large amount of glacial ice which then cooled and fragmented lava into gritty glass particles that were carried up with the rising volcanic plume.  Pictured above two days ago, lightning bolts illuminate ash pouring out of the Eyjafjallaj�kull volcano.
Saturn's Moons Dione and Titan from Cassini (2010-04-20)
What would it be like to see a sky with many moons?  Such is the sky above Saturn.  When appearing close to each other, moons will show a similar phase. A view with two of the more famous moons of Saturn in gibbous phase was captured last month by the robot spacecraft Cassini now orbiting Saturn.  Titan, on the left, is among the largest moons in the Solar System and is perpetually shrouded in clouds.  In 2005, the Huygens probe landed on Titan and gave humanity its first view of its unusual surface.  Dione, on the right, has less than a quarter of Titan's diameter and has no significant atmosphere. The above uncalibrated image was taken on April 10 after Cassini swooped by each moon the previous week.
Wide Angle: The Cat's Paw Nebula (2010-04-21)
Nebulae are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble.  Still, no known cat could have created the vast Cat's Paw Nebula visible in Scorpius.  At 5,500 light years distant, Cat's Paw is an emission nebula with a red color that originates from an abundance of ionized hydrogen atoms.  Alternatively known as the Bear Claw Nebula or NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years. Pictured above, a wide angle, deep field image of the  Cat's Paw nebula was culled from the second Digitized Sky Survey.
Venus, Mercury, and Moon (2010-04-22)
rlier this month, Venus and Mercury climbed into the western twilight, entertaining skygazers around planet Earth in a lovely conjunction of evening stars. Combining 8 images spanning April 4 through April 15, this composite tracks their progress through skies above Portsmouth, UK. Each individual image was captured at 19:50 UT. The sequential path for both bright planets begins low and to the left. But while Venus continues to swing away from the setting Sun, moving higher above the western horizon, Mercury first rises then falls. Its highest point is from the image taken on April 11. Of course on April 15, Venus and Mercury were joined by a young crescent Moon.
SDO: The Extreme Ultraviolet Sun (2010-04-23)
Don't panic, the Sun has not gone wild. But this wild-looking portrait of the nearest star to planet Earth was made on March 30th by the recently launched Solar Dynamics Observatory (SDO). Shown in false-color, the composite view covers extreme ultraviolet wavelengths and traces hot plasma at temperatures approaching 1 million kelvins. At full resolution, SDO image data is intended to explore solar activity in unprecedented detail. In fact, SDO will send 1.5 terabytes of data back each day, equivalent to a daily download of about half a million MP3 songs. New SDO data releases include a high-resolution movie of the large, eruptive prominence seen along the solar limb at the upper left.
NGC 1055: Galaxy in a Box (2010-04-24)
Big, beautiful spiral galaxy NGC 1055 is a dominant member of a small galaxy group a mere 60 million light-years away toward the intimidating constellation Cetus. Seen edge-on, the island universe spans about 100,000 light-years, similar in size to our own Milky Way. Colorful, spiky stars in this cosmic portrait of NGC 1055 are in the foreground, well within the Milky Way. But along with a smattering of more distant background galaxies, the deep image also reveals a curious box-shaped inner halo extending far above and below this galaxy's dusty plane. The halo itself is laced with faint, narrow structures, and could represent the mixed and spread out debris from a satellite galaxy disrupted by the larger spiral some 10 billion years ago.
Planetary Nebula Mz3: The Ant Nebula (2010-04-25)
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.
Dust Pillar of the Carina Nebula (2010-04-26)
Inside the head of this interstellar monster is a star that is slowly destroying it.  The monster, on the right, is actually an inanimate pillar of gas and dust that measures over a light year in length.  The star, not itself visible through the opaque dust, is bursting out partly by ejecting energetic beams of particles. Similar epic battles are being waged all over the star-forming Carina Nebula.  The stars will win in the end, destroying their pillars of creation over the next 100,000 years, and resulting in a new open cluster of stars. The pink dots around the image are newly formed stars that have already been freed from their birth monster.  The above image was released last week in commemoration of the Hubble Space Telescopes 20th year of operation.  The technical name for the stellar jets are Herbig-Haro objects.  How a star creates Herbig-Haro jets is an ongoing topic of research, but it likely involves an accretion disk swirling around a central star. A second impressive Herbig-Haro jet occurs diagonally near the image center.
The Bloop: A Mysterious Sound from the Deep Ocean (2010-04-27)
What created this strange sound in Earth's Pacific Ocean? Pictured above is a visual representation of a loud and unusual sound, dubbed a Bloop, captured by deep sea microphones in 1997. In the above graph, time is shown on the horizontal axis, deep pitch is shown on the vertical axis, and brightness designates loudness.  Although Bloops are some of the loudest sounds of any type ever recorded in Earth's oceans, their origin remains unknown. The Bloop sound was placed as occurring several times off the southern coast of South America and was audible 5,000 kilometers away.  Although the sound has similarities to those vocalized by living organisms, not even a blue whale is large enough to croon this loud.  The sounds point to the intriguing hypothesis that even larger life forms lurk in the unexplored darkness of Earth's deep oceans. A less imagination-inspiring possibility, however, is that the sounds resulted from some sort of iceberg calving.  No further Bloops have been heard since 1997, although other loud and unexplained sounds have been recorded.
Sunset on a Golden Sea (2010-04-28)
On April 17, the sky was clear and the Sun's colour was spectacular as night approached. This striking telescopic view even captures the Sun's swollen and distorted shape from the southern coast of the UK. Reflecting a bright column of sunlight, the sea also appears golden, with the horizon marked by the city of Portsmouth. Were the colours made more intense by volcanic dust? Maybe not. Normally, sunset (and sunrise) colours can still be very dramatic, especially when the atmosphere is clear and the Sun is viewed very near the horizon, as in this scene. But large dust particles, like those in the airline-thwarting ash clouds from the erupting Icelandic volcano Eyjafjallajökull, tend to create diffuse and subdued sunset colours.
Virgo Cluster Galaxy NGC 4731 (2010-04-29)
Barred spiral galaxy NGC 4731 lies some 65 million light-years away. The lovely island universe resides in the large Virgo cluster of galaxies. Colors in this well-composed, cosmic portrait, highlight plentiful, young, bluish star clusters along the galaxy's sweeping spiral arms. Its broad arms are distorted by gravitational interaction with a fellow Virgo cluster member, giant elliptical galaxy NGC 4697. NGC 4697 is beyond this frame above and to the left, but a smaller irregular galaxy NGC 4731A can be seen near the bottom in impressive detail with its own young blue star clusters. Of course, the individual, colorful, spiky stars in the scene are much closer, within our own Milky Way galaxy. NGC 4731 itself is well over 100,000 light-years across.
Mars in a Manger (2010-04-30)
At opposition in late January, Mars shone very brightly in planet Earth's night sky, among the stars of the constellation Cancer the Crab. Since then the Red Planet has been fading, but still lingers in Cancer during April and May. In mid-April, Mars wandered remarkably close to Cancer's famous star cluster M44, the Beehive Cluster. M44 is also known by an older name, Praesepe, Latin for cradle or manger. Captured in this 60 second time exposure made on April 14, a yellow-tinged Mars and M44 are near the center of the field, seemingly just beyond the reach of a pine tree. Of course, M44's stars are about 600 light-years away, while Mars was more like 600 light-seconds from Earth. The digital photograph was made with a camera mounted on a telescope tracking the stars through dark skies above a camp ground in Virginia, USA. During the exposure, passing car lights briefly illuminated the tree branches.
A Pulsar's Hand (2010-05-01)
As far as pulsars go, PSR B1509-58 appears young. Light from the supernova explosion that gave birth to it would have first reached Earth some 1,700 years ago. The magnetized, 20 kilometer-diameter neutron star spins 7 times per second, a cosmic dynamo that powers a wind of charged particles. The energetic wind creates the surrounding nebula's X-ray glow in this tantalizing image from the Chandra X-ray Observatory. Low energy X-rays are in red, medium energies in green, and high energies in blue. The pulsar itself is in the bright central region. Remarkably, the nebula's tantalizing, complicated structure resembles a hand. PSR B1509-58 is about 17,000 light-years away in the southern constellation Circinus. At that distance the Chandra image spans 100 light-years.
The Coma Cluster of Galaxies (2010-05-02)
Almost every object in the above photograph is a galaxy.  The Coma Cluster of Galaxies pictured above is one of the densest clusters known - it contains thousands of galaxies.  Each of these galaxies houses billions of stars - just as our own Milky Way Galaxy does.  Although nearby when compared to most other clusters, light from the Coma Cluster still takes hundreds of millions of years to reach us.  In fact, the Coma Cluster is so big it takes light millions of years just to go from one side to the other!  Most galaxies in Coma and other clusters are  ellipticals, while most galaxies outside of clusters are spirals.  The nature of Coma's X-ray emission is still being investigated.
Spiral Galaxy NGC 3190 Almost Sideways (2010-05-03)
Some spiral galaxies are seen almost sideways.  NGC 3190, one such galaxy, is the largest member of the Hickson 44 Group, one of the nearer groups of galaxies to our own Local Group of galaxies. Pictured above, finely textured dust lanes surround the brightly glowing center of this picturesque spiral. Gravitational tidal interactions with other members of its group have likely caused the spiral arms of NGC 3190 to appear asymmetric around the center, while the galactic disk also appears warped.   NGC 3190 spans about 75,000 light years across and is visible with a small telescope toward the constellation of the Lion (Leo).
A Hall of Mountain Fogbows (2010-05-04)
If you tried to enter this hall of fog, you would find it dissipates around you. The hall is actually an optical illusion created by sunlight backscattering off of a cloud passing below the peak of the mountain from which this picture was taken. Known as a fogbow and similar in some ways to "the glory", the phenomenon is sometimes seen from airplanes.  The ring's center appears near the image bottom where the shadow of the photographer is visible. This shadow would likely change as clouds passed, creating a faux moving giant known as the Brocken Spectre.  In the picture, several concentric rings of the fogbow appear to create a hall for this mountain king.  The cause of fogbow supernumeraries arcs and glories have only been understood recently and are relatively complex.  Briefly, small droplets of water reflect, refract, and diffract sunlight backwards towards the Sun. Atmospheric backscattering phenomena have a counterpart in astronomy, where looking out from planet Earth in the direction opposite the Sun yields a bright spot called the gegenschein.    Note: The APOD text was updated for accuracy on 2010 May 9.
The Faces of Mars (2010-05-05)
husiastic astro-artists ranging from expert to beginner, the youngest age 10, all contributed their work to this entertaining panel featuring different faces of Mars. Their sketches are all based on telescopic views of the Red Planet from earlier this year, near its 2010 opposition. Mars offers the best telescopic views at opposition, since that's when it is closest and opposite the Sun in planet Earth's sky. Arranged in a spiral pattern, the sketches are positioned to follow the planet's rotation.  No canals are visible(!), but large surface markings such as the dramatic, dark Syrtis Major are easily identified. As often seen through an astronomical telescope eyepiece, the planet's orientation is inverted, with Mars' north polar cap at the bottom.
Northern and Southern Owls (2010-05-06)
Captured in colorful telescopic portraits, two cosmic owls glare back toward planet Earth in this intriguing comparison of planetary nebulae. On the left is M97 in the constellation Ursa Major, also known in the northern hemisphere as the Owl Nebula. On the right is its visual counterpart, the southern Owl Nebula in the constellation Hydra, cataloged as PLN 283+25.1. Both nebulae are remarkably symmetric, round, and similar in size, some 2 light-years across or about 2,000 times the diameter of Neptune's orbit. Planetary nebulae are produced during a final phase in the life of a sun-like star, an example of the fate that awaits the Sun when it runs out of nuclear fuel in another 5 billion years. Both images were made using narrowband filters and different color mappings. The image of the southern Owl also includes broadband data, bringing out the surrounding star field.
The Antennae (2010-05-07)
Some 60 million light-years away in the southerly constellation Corvus, two large galaxies collided. But the stars in the two galaxies cataloged as NGC 4038 and NGC 4039 don't collide in the course of the ponderous, billion year or so long event. Instead, their large clouds of molecular gas and dust do, triggering furious episodes of star formation near the center of the cosmic wreckage. Spanning about 500 thousand light-years, this stunning view also reveals new star clusters and matter flung far from the scene of the accident by gravitational tidal forces. Of course, the visual appearance of the far-flung arcing structures gives the galaxy pair its popular name - The Antennae.
Atlantis Lift Off (2010-05-08)
Atlantis has lifted off, but not from launch pad 39A. Instead, this sharp, wide-angle photo taken on April 13, shows the space shuttle orbiter lifted off the floor of Kennedy Space Center's Vehicle Assembly Building. Shortly afterwards, Atlantis was attached to an external fuel tank and solid rocket boosters prior to roll out. Now resting on pad 39A, Atlantis is scheduled for its actual liftoff on May 14. Embarking on the STS-132 mission to the International Space Station , that launch will represent the final scheduled launch for Atlantis. Atlantis was named for a sailing ship operated for the Woods Hole Oceanographic Institute from 1930 to 1966. The maiden voyage of the Atlantis, Orbiter Vehicle-104, began on October 3, 1985. In 1991, Atlantis deployed the Compton Gamma Ray Observatory.
Halo of the Cat's Eye (2010-05-09)
The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its haunting symmetries are seen in the very central region of this stunning false-color picture, processed to reveal the enormous but extremely faint halo of gaseous material, over three light-years across, which surrounds the brighter, familiar planetary nebula. Made with data from the Nordic Optical Telescope in the Canary Islands, the composite picture shows extended emission from the nebula. Planetary nebulae have long been appreciated as a final phase in the life of a sun-like star. Only much more recently however, have some planetaries been found to have halos like this one, likely formed of material shrugged off during earlier active episodes in the star's evolution. While the planetary nebula phase is thought to last for around 10,000 years, astronomers estimate the age of the outer filamentary portions of this halo to be 50,000 to 90,000 years.
Herschel Crater on Mimas of Saturn (2010-05-11)
Why is this giant crater on Mimas oddly colored? Mimas, one of the smaller round moons of Saturn, sports Herschel crater, one of the larger impact craters in the entire Solar System. The robotic Cassini spacecraft now orbiting Saturn took the above image of Herschel crater in unprecedented detail while making a 10,000-kilometer record close pass by the icy world just over one month ago. Shown in contrast-enhanced false color, the above image includes color information from older Mimas images that together show more clearly that Herschel's landscape is colored slightly differently from more heavily cratered terrain nearby.  The color difference could yield surface composition clues to the violent history of Mimas.  An impact on Mimas much larger than the one that created the 130-kilometer Herschel would likely have destroyed the entire world.
M72: A Globular Cluster of Stars (2010-05-12)
Globular clusters once ruled the Milky Way.  Back in the old days, back when our Galaxy first formed, perhaps thousands of globular clusters roamed our Galaxy.  Today, there are less than 200 left.  Many globular clusters were destroyed over the eons by repeated fateful encounters with each other or the Galactic center.  Surviving relics are older than any Earth fossil, older than any other structures in our Galaxy, and limit the universe itself in raw age.  There are few, if any, young globular clusters in our Milky Way Galaxy because conditions are not ripe for more to form.  Pictured above by the Hubble Space Telescope are about 100,000 of M72's stars. M72, which spans about 50 light years and lies about 50,000 light years away, can be seen with a small telescope toward the constellation of the Water Bearer (Aquarius).
The Magnificent Horsehead Nebula (2010-05-13)
Sculpted by stellar winds and radiation, a magnificent interstellar dust cloud by chance has assumed this recognizable shape.  Fittingly named the Horsehead Nebula, it is some 1,500 light-years distant, embedded in the vast Orion cloud complex. About five light-years "tall", the dark cloud is cataloged as Barnard 33 and is visible only because its obscuring dust is silhouetted against the glowing red emission nebula IC 434.  Stars are forming within the dark cloud. Contrasting blue reflection nebula NGC 2023, surrounding a hot, young star, is at the lower left.  The gorgeous color image combines both narrowband and broadband images recorded using three different telescopes.
Iguaçu Starry Night (2010-05-14)
The arc of the southern Milky Way shone brightly on this starry night. Captured on May 4, in the foreground of this gorgeous skyview is the rainforest near the spectacular Iguaçu Falls and national park at the border of Brazil and Argentina. Looking skyward along the Milky Way's arc from the left are Alpha and Beta Centauri, the Coalsack, the Southern Cross, and the Carina Nebula. Sirius, brightest star in planet Earth's night sky is at the far right.  Brilliant Canopus, second brightest star in the night, and our neighboring galaxies the Large and Small Magellanic clouds, are also included in the scene. For help finding them, just slide your cursor over the image. Much closer to home, lights near the center along the horizon are from Argentina's Iguazú Falls International Airport.
The Elusive Jellyfish Nebula (2010-05-15)
Normally faint and elusive, the Jellyfish Nebula is caught in this alluring, false-color, telescopic view. Flanked by two bright stars, Mu and Eta Geminorum, at the foot of a celestial twin, the Jellyfish Nebula is the brighter arcing ridge of emission with dangling tentacles below and right of center. In fact, the cosmic jellyfish is seen to be part of bubble-shaped supernova remnant IC 443, the expanding debris cloud from a massive star that exploded. Light from the explosion first reached planet Earth over 30,000 years ago. Like its cousin in astrophysical waters the Crab Nebula supernova remnant, IC 443 is known to harbor a neutron star, the remnant of the collapsed stellar core. Emission nebula Sharpless 249 fills the field at the upper left. The Jellyfish Nebula is about 5,000 light-years away. At that distance, this image would be about 300 light-years across. The color scheme used in the narrowband composite was made popular in Hubble Space Telescope images, mapping emission from oxygen, hydrogen, and sulfur atoms to blue, green and red colors.
Crescent Venus and Moon (2010-05-16)
There's something behind these clouds.  Those faint graceful arcs, upon inspection, are actually far, far in the distance.  They are the Earth's Moon and the planet Venus.  Both the Moon and Venus are bright enough to be seen during the day, and both are quite capable of showing a crescent phase.   To see Venus, which appears quite small, in a crescent phase requires binoculars or a telescope. In the above dramatic daytime image taken from Budapest, Hungary in 2004, the Moon and Venus shared a similar crescent phase a few minutes before the Moon eclipsed the larger but more distant world.   Similarly, visible today in parts of Africa and Asia, a crescent Moon will again eclipse Venus during the day. About an hour after the above image was taken, Venus reappeared.
Panorama of the Whale Galaxy (2010-05-17)
The see the full length of this blue whale, scroll right. NGC 4631 is a big beautiful spiral galaxy seen edge-on at only about 30 million light-years away.  This galaxy's slightly distorted wedge shape led to its popular moniker of the Whale galaxy.  The Whale's dark interstellar dust clouds and young bright blue star clusters highlight this panoramic color image. The band of NGC 4631 not only appears similar to band of our own Milky Way Galaxy, but its size is truly similar to our Milky Way as well.  The galaxy is also known to have spouted a halo of hot gas glowing in x-rays. The Whale galaxy spans about 140,000 light years and can be seen with a small telescope toward the constellation of the Hunting Dogs (Canes Venatici).