omnianasa/nasa-apod-metadata huggingface dataset:
The Andromeda Deep Field (2003-05-19)
What can you learn from looking into the depths of space?  In an effort to find out true ages of stars in neighboring Andromeda galaxy's halo, astronomers stared into the galaxy giant with the new Advanced Camera for Surveys through the Hubble Space Telescope.  The resulting exposure of over three days, shown above, is the deepest exposure in visible light ever taken, although shorter in duration than the multi-wavelength effort toward the Hubble Deep Field.  The final image illuminated not only Andromeda (M31) but the distant universe.  Andromeda's halo stars turned out to be have a wider range of ages than our Milky Way's halo stars, likely indicating more encounters with small neighboring galaxies.  Visible on the above left is one of Andromeda's globular star clusters, while literally thousands of background galaxies are seen in the distance universe, far beyond M31.
A Primordial Quasar (2003-05-20)
What did the first quasars look like?  The nearest quasars are now known to be supermassive black holes in the centers of galaxies.  Gas and dust that falls toward a quasar glows brightly, sometimes outglowing the entire home galaxy.  The quasars that formed in the first billion years of the universe are more mysterious, though, with even the nature of the surrounding gas still unknown.  Above, an artist's impression shows a primordial quasar as it might have been, surrounded by sheets of gas, dust, stars, and early star clusters.  Exacting observations of three distant quasars now indicate emission of very specific colors of the element iron.  These Hubble Space Telescope observations, which bolster recent results from the WMAP mission, indicate that a whole complete cycle of stars was born, created this iron, and died within the first few hundred million years of the universe.
Copper Moon, Golden Gate (2003-05-21)
When the Moon rose over San Francisco's Golden Gate Bridge on May 15, both bridge and Moon were in already in Earth's shadow. Of course, the bridge is in the Earth's shadow nightly, while the Moon only has that opportunity about twice a year, during a lunar eclipse. And even though in western North America the total phase of the lunar eclipse began before moonrise, many in areas with clear skies came out to enjoy the spectacle. For this eclipse, skygazers reported a darker than normal, copper-colored Moon during totality. The dramatic color is evident in this multiple exposure of the reddened Moon rising, taken by astrophotographer Evad Damast. Damast viewed the eclipse from the Marin Headlands north and west of the famous bridge, looking back toward the bay and the city lights.
Eclipsed Moon Montage (2003-05-22)
After watching this month's lunar eclipse, amateur astronomer Sebastien Gauthier carefully composed this montage of telescopic images of the Moon sliding through planet Earth's shadow. While the deepest part of the total eclipse corresponds to the central exposure, the play of light across the lunar surface nicely demonstrates that the planet's shadow is not uniformly dark as it extends into space. In fact, lunar maria and montes are still visible in the dimmed, reddened sunlight scattered into the cone-shaped shadow region, or umbra, by Earth's atmosphere. For this eclipse, the Moon's trajectory took it North of the umbra's darker core, seen here cast over the Moon's cratered southern highlands. Gauthier's telescope and camera equipment were set up near the Trois-Rivieres College Champlain Observatory in Quebec, Canada.
Eclipsed Moon and Stars (2003-05-23)
Half-shadowed by the Earth, the Moon takes on a remarkable appearance against a field of stars in this intriguing telephoto picture recorded during a partial phase of last week's lunar eclipse. The picture is not a composite, but it has been digitally enhanced to bring out features covering a large range in brightness. On the Moon itself, surface details are visible in both the bright uneclipsed portion in direct sunlight, and the very much dimmer copper-colored, eclipsed region. Also much fainter than the Moon's sunlit surface, the background star field, along with the unusual lighting, seems to contribute to an eerie "3D" perception of the lunar orb. Canadian astrophotographer Jay Ouellet took the picture from l'Observatoire de la Decouverte in Val Belair, a suburb of Quebec City, where about 200 skygazers gathered to enjoy the celestial exposition.
M74: The Perfect Spiral (2003-05-24)
If not perfect, then this spiral galaxy is at least one of the most photogenic. An island universe of about 100 billion stars, 30 million light-years away toward the constellation Pisces, NGC 628 or M74 presents a gorgeous face-on view to earthbound astronomers. Classified as an Sc galaxy, the grand design of M74's graceful spiral arms traced by bright blue star clusters and dark cosmic dust lanes, is similar in many respects to our own home galaxy, the Milky Way. Recorded with a 28 million pixel detector array, this impressive image celebrated first light for the Gemini Multi-Object Spectrograph (GMOS), a state-of-the-art instrument operational at the 8-meter Gemini North telescope. The Gemini North Observatory gazes into the skies above Mauna Kea, Hawaii, USA, while its twin observatory, Gemini South, operates from Cerro Pach�n in central Chile.
Spiral Galaxy NGC 253 Almost Sideways (2003-05-25)
NGC 253 is a normal spiral galaxy seen here almost sideways.  It is the largest member of the Sculptor Group of Galaxies, the nearest group to our own Local Group of Galaxies.  NGC 253, pictured above, appears visually as one of the brightest spirals on the sky, and is easily visible in southern hemisphere with a good pair of binoculars.  The type Sc galaxy is about 10 million light years distant.  NGC 253 is considered a starburst galaxy because of high star formation rates and dense dust clouds in its nucleus.  The energetic nuclear region is seen to glow in X-ray and gamma-ray light.
The Earth and Moon from Mars (2003-05-26)
What does Earth look like from Mars?  The first image of Earth from the red planet was captured earlier this month by the camera onboard the Mars Global Surveyor spacecraft currently orbiting Mars.  Features visible on Earth include the Pacific Ocean, clouds, much of South America, and part of North America.  Earth's Moon is visible on the upper right, with the crater Tycho brightening the lower part.  Previously, Earth has been imaged from the Moon and spacecraft across the Solar System.
A Mercury Transit Sequence (2003-05-27)
rlier this month, the planet Mercury crossed the face of the Sun, as seen from Earth.  Because the plane of Mercury's orbit is not exactly coincident with the plane of Earth's orbit, Mercury usually appears to pass over or under the Sun.  The above time-lapse sequence, superimposed on a single frame, was taken from a balcony in Belgium on May 7 and shows the entire transit.  The solar crossing lasted over five hours, so that the above 23 images were taken roughly 15 minutes apart.  The north pole of the Sun, the Earth, Mercury's orbit, although all different, all occur in directions slightly above the left of the image. Near the center and on the far right, sunspots are visible.
SNR 0103-72.6: Oxygen Supply (2003-05-28)
A supernova explosion, a massive star's inevitable and spectacular demise, blasts back into space debris enriched in the heavy elements forged in its stellar core. Incorporated into future stars and planets, these are the elements ultimately necessary for life. Seen here in a false-color x-ray image, supernova remnant SNR 0103-72.6 is revealed to be just such an expanding debris cloud in neighboring galaxy, the Small Magellanic Cloud. Judging from the measured size of the expanding outer ring of shock-heated gas, about 150 light-years, light from the original supernova explosion would have first reached Earth about 10,000 years ago. Hundreds of supernova remnants have been identified as much sought after astronomical laboratories for studying the cycle of element synthesis and enrichment, but the x-ray data also show that the hot gas at the center of this particular supernova remnant is exceptionally rich in neon and oxygen.
Frizion Illume (2003-05-29)
Scientific images of cosmic dust clouds or even frozen water can be esthetic too. In fact, this picture of thin layers of forming ice crystals uses a scientific understanding of light's wave properties solely for artistic purposes. Titled "Illume", the picture was created by astrophysicist Peter Wasilewski. To make the picture, the crystals were illuminated by light shining through a polarizing filter -- a filter that restricts the otherwise randomly oriented light waves to vibrate in only one direction.  While passing through the ice, different colors of the polarized light are then refracted and reflected along slightly different paths by the delicate crystalline layers. Viewing the scene with a second polarizing filter brings out the wondrous display of structure and color. Painting with "light, the laws of physics, and an attitude" Wasilewski has created a series of these evocative ice images that he refers to as Frozen Vision or Frizion.
Ring of Fire Revisited (2003-05-30)
rly on Saturday, May 31 (UT) the new Moon will once again slide across the Sun's fiery disk, and once again an annular solar eclipse will be the result -- since the Moon's apparent diameter will be a little too small to completely cover the Sun. But this time celestial geometry has conspired to produce a broad D-shaped region for viewing the annular phase that extends into the far northern hemisphere, rather than creating a thin track racing across land and sea. The characteristic ring of fire will be visible from northern Scotland, Iceland, and parts of Greenland. Otherwise a partial eclipse will be more widely visible as across Europe, along with parts of Asia and North America, the Moon will appear to take a "bite" out of the Sun. While the northerly observers might certainly expect a dramatic view, it will probably not look quite like this one, recorded with a foreground of palm trees during a 1992 annular eclipse. Want to watch Saturday's eclipse on the web? Check out the planned webcasts from Astronet.
NGC 1818: Pick A Star (2003-05-31)
This is NGC 1818, a youthful, glittering cluster of 20,000 stars residing in the Large Magellanic Cloud, 180,000 light-years away. Pick a star. Any star. Astronomers might pick the unassuming bluish-white one (circled) which appears to be a hot newly formed white dwarf star. What makes it so interesting? The standard astronomical wisdom suggests that stars over 5 times as massive as the sun rapidly exhaust their nuclear fuel and end their lives in a spectacular supernova explosion. With less than this critical mass they evolve into red giants, pass through a relatively peaceful planetary nebula phase, and calmly fade away as white dwarf stars like this one. Except that as a member of the NGC 1818 cluster, this new white dwarf would have evolved from a red giant star over 7.6 times as massive as the sun -- which should have exploded! Its discovery will likely force astronomers to revise the limiting mass estimate for supernovae upward.
GRO J1655-40: Evidence for a Spinning Black Hole (2003-06-01)
In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole.  Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.  The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second.  Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly.  What physical mechanisms actually cause the flickering -- and a slower quasi-periodic oscillation (QPO) -- in  accretion disks surrounding black holes and neutron stars remains a topic of much research.
The Fogs of Mars (2003-06-02)
Fogs of clouds and dust covered parts of southern Mars during last Martian winter.  Giant volcanoes, such as Ascraeus Mons, the central circular feature near the top of the image, were surrounded by large water clouds.  Slightly southwest, Pavonis Mons and Arisa Mons also peeked above their water clouds.  The rough terrain below center is Labyrinthus Noctis, a maze of deep troughs running over 200 kilometers long.   Directly south, a large white dust storm fogs Syria Planum, a large plateau.  This image mosaic was taken by the Mars Global Surveyor spacecraft currently orbiting Mars.  Soon, five more Earth-launched spacecraft should arrive at the Red Planet, named for the Roman god of war.
The Milky Way Behind an Eclipsed Moon (2003-06-03)
What's behind the Moon? Each month, our Moon passes in front of -- and outshines -- many an interesting star field.  Exceptions occur during a new Moon and during a total eclipse.  In the background of a new Moon is usually the Sun, an even brighter orb that even more easily outshines everything behind it, except during a total solar eclipse.  Even the longest total solar eclipse lasts just a few minutes, while the Sun's corona still remains bright.  During a total lunar eclipse, however, the full Moon dims and a majestic star field may present itself for an hour or more.  Such was the case during the middle of last month, when a rare glimpse of an eclipsed Moon superposed in front of the disk of our home Milky Way Galaxy was captured.  Although fully in the Earth's shadow, the eclipsed Moon is still the brightest object on the right.  The above image was captured during sub-zero weather from the Teide 2003 expedition to Mirador del Pico Viejo, a mountain in the Canary Islands, Spain, off the northwest coast of Africa.
Eclipse in the Mist (2003-06-04)
The Sun and Moon rose together over much of Europe on the morning of May 31st with the first solar eclipse of 2003 already in progress. And while sightings of the full annular phase of the eclipse were restricted to far northern regions, early morning risers were still treated to inspiring views of two celestial bodies which are most important to life on planet Earth. Following the dawn's spectacle from Charneux, Belgium, astrophotographer Olivier Meeckers recorded this evocative image of the partially eclipsed Sun rising above a primeval apparition of mists and trees. Last month was indeed a rewarding one for eclipse watchers as May's full Moon and (second) new Moon lined up for their respective lunar and solar eclipses. November 2003 will also host both a total lunar and total solar eclipse.
Ring of Fire from Cape Wrath (2003-06-05)
If the Moon's apparent diameter is not quite large enough to cover the Sun during a solar eclipse, an annular eclipse can be the result -- a spectacle of silhouetted Moon surrounded by a solar "ring of fire". Just such a view was possible for observers in the far northern hemisphere as the new Moon slid across the solar disk on May 31st. Still, for astronomical adventurers at Cape Wrath on the northwestern coast of Scotland, the eastern sky was cloudy on eclipse day. But fortunately the Sun became visible a few minutes prior to the annular phase and determined astronomer Hans Coeckelberghs was able to capture this dramatic telescopic image of the eclipsed Sun's ring of fire looming through a reddened, cloud-streaked sky. Not to be outdone by the north, the far southern hemisphere will host the next solar eclipse, with the path of totality racing across Antarctica on November 23rd.
Sun, Moon, Hot Air Balloon (2003-06-06)
Anticipating the celestial shadow play of a solar eclipse, sky gazers across Germany watched the Sun rise on May 31. In Bonn, astrophotographer Thilo Kranz had set up his small refractor telescope and camera on the Kennedy Bridge across the Rhein river to get a good view to the northeast. The timing of this eclipse must have seemed ideal for a local balloon flight too, as hot air balloonists also favor early morning hours with usually calm surface winds. Kranz and colleagues had noticed a balloon drifting in the hazy sky near the horizon and speculated about viewing the eclipse from on board. But when the eclipsed Sun finally emerged into view they were delighted to see the lighter-than-air craft make the occasion a very special show from their own vantage point. In fact, in the central panel of this montage of Kranz's telescopic eclipse images, the silhouetted balloon reminds the APOD editors of a remarkably well-fed exclamation mark!
The X-ray Timing Explorer (1996-01-03)
Launched Saturday on a Delta rocket, the X-ray Timing Explorer (XTE) will watch the sky for rapid changes in X-rays. XTE carries three separate X-ray telescopes.  The Proportional Counter Array (PCA) and the High Energy X-ray Timing Experiment (HEXTE) will provide the best timing information in the widest X-ray energy range yet available.  They will observe stellar systems that contain black holes, neutron stars, and white dwarfs as well as study the X-ray properties of the centers of active galaxies. XTE's All Sky Monitor (ASM) will scan the sky every 90 minutes to find new X-ray transients and track the variability of old ones. XTE has a planned life time of two years.
Symbiotic Star System R Aquarii (1996-01-04)
Sometimes stars work together to create a spectacular display.  Such is the case with the binary star system R Aquarii - a "symbiotic" star system. Here two stars, a variable giant and a white dwarf companion - create both a nebula and a jet.  Light from the giant star and the unusually shaped nebula are visible in the above photograph. The two visible shells in the nebula likely resulted from two separate outburst events. Much about symbiotic star systems remains unknown.
The Toby Jug Nebula (1996-01-05)
Is the only thing unusual about this nebula its shape?  Pictured above is the IC 2220 - the Toby Jug Nebula - a reflection nebula surrounding a normal red giant star. Reflection nebulae shine by light reflected from the central star(s). This nebula appears to have been created from the current phase of mass-loss from the central star. Normal gas and dust compose the nebula.  The nebula's peculiar but photogenic "bi-polar, bi-conical" shape, however, continue to make it a popular object of study.
Dwarf Elliptical Galaxy M32 (1996-01-06)
Being the largest galaxy around can sometimes make you popular.  Pictured is M31's companion galaxy M32. M31, the Andromeda galaxy, is the largest galaxy in our Local Group of galaxies - even our tremendous Milky Way Galaxy is smaller. Little M32 is visible in most pictures of M31 - it is the small circular spot north of M31's center.  M32 is a dwarf elliptical galaxy. Elliptical galaxies have little or no measurable gas or dust - they are composed completely of stars and typically appear more red than spiral galaxies. Elliptical galaxies do not have disks - they generally have oblong shapes and therefore show elliptical profiles on the sky.
Mercury Astronauts and a Redstone (1996-01-07)
Space suited project Mercury astronauts John H. Glenn, Virgil I. Grissom, and Alan B. Shepard Jr. (left to right) are pictured here posing in front of a Redstone rocket in this 1961 NASA publicity photo. Project Mercury was the first U.S. program designed to put humans in space. It resulted in 6 manned flights using one-man capsules and Redstone and
Local Group Galaxy NGC 205 (1996-01-08)
The Milky Way Galaxy is not alone.  It is part of a gathering of about 25 galaxies known as the Local Group. Members include the Great Andromeda Galaxy (M31), M32, M33, the Large Magellanic Clouds, the Small Magellanic Clouds, Dwingeloo 1, several small irregular galaxies, and many dwarf elliptical galaxies. Pictured is one of the many dwarf ellipticals: NGC 205.  Like M32, NGC 205 is a companion to the large M31, and can sometimes be seen to the south of M31's center in photographs.  The above image shows this galaxy to be unusual for an elliptical galaxy in that it contains at least two dust clouds (at 7 and 11 o'clock - they are visible but hard to spot) and signs of recent star formation.  This galaxy is sometimes known as M110, although it was actually not part of Messier's original catalog.
M100 and the Expanding Universe (1996-01-09)
The distance to the swirling grand design spiral M100 is causing quite a stir among astronomers. Many believe that the Hubble Space Telescope's recent distance measurement to this galaxy accurately calibrates the expansion rate of the universe. Others believe this distance measurement is misleading. The universe's expansion rate is usually given as a quantity called "Hubble's constant", a factor dividing well-measured recession velocity of a galaxy to give actual distance. Scientific debate over the value of Hubble's constant has been ongoing since it was first measured by Edwin Hubble in 1929. A real live debate involving the value of Hubble's constant titled "The Scale of the Universe" will occur in April 1996 in Washington, DC.
The Cepheids of M100 (1996-01-10)
Can this blinking star tell us how fast the universe is expanding? Many astronomers also believe it may also tell us the age of the universe! The photographed "Cepheid variable" star in M100 brightens and dims over the course of days as its atmosphere expands and contracts. A longer blinking cycle means an intrinsically brighter star. Cepheids variable stars are therefore used as distance indicators. By noting exactly how long the blinking period is and exactly how bright the star appears to be, one can tell the distance to the star and hence the star's parent galaxy. This distance can then be used to match-up easily measured recessional velocity ("redshift") with distance. Once this "Hubble relation" is determined for M100, it should be the same for all galaxies - and hence tell us how fast the universe is expanding. The exact magnitude of this calibration is under dispute and so a real live debate involving the value of Hubble's constant titled "The Scale of the Universe" will occur in April 1996 in Washington, DC.
Lasers in Eta Carinae (1996-01-11)
Have you heard about the great LASER light show in the sky? Well, nobody had until it was announced just yesterday by a team led by K. Davidson (U. Minnesota) and S. Johansson (U. Lund).  The research team discovered that the unusually variable star Eta Carinae emits ultraviolet light of such a specific color it is most probably LASER light! The artist's conception shown above depicts a possible model for the Hubble Space Telescope observations. In this model, Eta Carinae emits many LASER beams from its surrounding cloud of energized gas.  Infrared LASERS and microwave MASERS are extremely rare astrophysical phenomena, but this ultraviolet LASER is the first of its kind to be discovered.
Mare Orientale (1996-01-12)
Looking like a target ring bull's-eye, the Mare Orientale is one of the most striking large scale lunar features. Located on the Moon's extreme western edge, this impact basin is unfortunately difficult to see from an earthbound perspective. It is over 3 billion years old, about 600 miles across and was formed by the impact of an asteroid sized object. The collision caused ripples in the lunar crust resulting in the three concentric circular features visible in this 1967 photograph made by NASA's Lunar Orbiter 4. Molten lava from the Moon's interior flooded the impact site through the fractured crust creating a mare. Dark, smooth regions on the moon are called mare (Latin for sea), because early astronomers thought these areas might be oceans.