omnianasa/nasa-apod-metadata huggingface dataset:
Mars Climate Orbiter Launches (1998-12-24)
Looking down from atop a Delta II rocket blasting skyward, solid fuel boosters fall away (left) and the Earth's limb slides into view. These pictures from the launch of the Mars Climate Orbiter were taken as it climbed away from Cape Canaveral Air Station Space Launch Complex 17 on December 11. This spacecraft won't arrive at Mars in time for Christmas though, as its cruise to the red planet will require about 9 1/2 Earth months to complete. Once it does get there it will use aerobraking to help establish a polar science mapping orbit for studying the martian atmosphere. The orbiter is also scheduled to act as a communications relay for the soon to be launched Mars Polar Lander.
Nebulae For Christmas (1998-12-25)
If our Galaxy were a Christmas tree, planetary nebulae would adorn it like colorful lighted ornaments twinkling on a cosmic scale. Glowing shrouds of gas ejected by red giant stars, planetary nebulae like NGC 6578 (left) and IC 3568 last for a mere 10,000 years or so as swollen stellar giants are transformed into fading, cooling white dwarf stars. Meanwhile ... have a safe, happy holiday season and Best Wishes to all from APOD!
Gamma-Ray Quasar (1998-12-26)
The bright object in the center of the false color image above is quasar 3C279 viewed in gamma-rays, photons with more than 40 million times the energy of visible light. Like all quasars, 3C279 is a nondescript, faint, star-like object in the visible sky. Yet, in June of 1991 a gamma-ray telescope onboard NASA's orbiting Compton Gamma Ray Observatory unexpectedly discovered that it was one of the brightest objects in the gamma-ray sky. Shortly after this image was recorded the quasar faded from view at gamma-ray energies. Astronomers are still trying to understand what causes these enigmatic objects to flare so violently. Another quasar, 3C273, is faintly visible above and to the right of center.
M2-9: Wings of a Butterfly Nebula (1998-12-27)
Are stars better appreciated for their art after they die?  Actually, stars usually create their most artistic displays as they die.  In the case of low-mass stars like our Sun and M2-9 pictured above, the stars transform themselves from normal stars to white dwarfs by casting off their outer gaseous envelopes.  The expended gas frequently forms an impressive display called a planetary nebula that fades gradually over thousand of years. M2-9, a butterfly planetary nebula 2100 light-years away shown in representative colors, has wings that tell a strange but incomplete tale. In the center, two stars orbit inside a gaseous disk 10 times the orbit of Pluto.  The expelled envelope of the dying star breaks out from the disk creating the bipolar appearance.  Much remains unknown about the physical processes that cause planetary nebulae.
NEAR to Asteroid Eros (1998-12-28)
On December 23, the NEAR spacecraft flew by asteroid 433 Eros.  NEAR was originally scheduled to brake and orbit Eros, but an unexpected shutdown of its main engine caused this plan to be aborted.  NEAR will now be reset and attempt to return to orbit Eros in early 2000. The above  image sequence was taken as NEAR approached Eros.  The rotation of the asteroid is visible in the successive frames.  When NEAR is fully operational, it will likely provoke the world's largest telescopes to point not toward asteroid Eros but to positions indicated by another of NEAR's instruments: its gamma-ray burst (GRB) detector.  NEAR's distant GRB detector happens now to be in a unique position to contribute information crucial to the rapid acquisition of accurate GRB positions.
A Geminid From Gemini (1998-12-29)
The Leonid meteor shower was not the only good meteor shower this season.  Earlier this month, the annual Geminids meteor shower peaked, featuring as many as 140 meteors per hour from some locations.  Geminid meteors can be seen streaking away from the constellation of Gemini, as depicted in the above all-sky photograph.  The origin of the Geminid meteors is somewhat uncertain but thought to be small bits broken off the unusual asteroid 3200 Phaetheon.  Many observers reported that the 1998 Geminids were typically less bright than the 1998 Leonids, but appeared more bunched, with groups of two or three meteors sometimes appearing simultaneously.  Next years' Geminids might be better yet.
Supernova 1994D and the Unexpected Universe (1998-12-30)
Far away, long ago, a star exploded.  Supernova 1994D, visible as the bright spot on the lower left, occurred in the outskirts of disk galaxy NGC 4526. Supernova 1994D was not of interest for how different it was, but rather for how similar it was to other supernovae.  In fact, the light emitted during the weeks after its explosion caused it to be given the familiar designation of a Type Ia supernova.  If all Type 1a supernovae have the same intrinsic brightness, then the dimmer a supernova appears, the farther away it must be.  By calibrating a precise brightness-distance relation, astronomers are able to estimate not only the expansion rate of the universe (parameterized by the Hubble Constant), but also the geometry of the universe we live in (parameterized by Omega and Lambda). The large number and great distances to supernovae measured in 1998 have been interpreted as indicating that we live in a previously unexpected universe.
The Year of Distant Supernovae (1998-12-31)
Distant supernovae were among topics at the forefront of astronomy during 1998.  Two independent groups raced to deploy large telescopes to scan the sky, discovering and analyzing far-off supernovae with the promise of calibrating the geometry of our universe.  The results were surprising -- implying an unexpected universe rich in not only dark matter (Omega in matter ~ 0.3) but also in dark energy (Lambda ~ 0.7).  Skeptics remain cautious, however, some waiting for more than a few high- redshift supernovae to light the way, while others waiting for verification methods not vulnerable to the same types of systematic errors.  Pictured above are several of the distant supernovae that have ignited modern cosmology.
ESO202-G23: Merging Galaxies (1999-01-01)
SO202-G23 is a colorful mess.  It is a collision between two galaxies taking place over hundreds of millions of years.  The representative colors give astronomers some idea of what is going on. Visible in this jumble is an  active nucleus spewing ultraviolet radiation which lights up surrounding gas (blue); galactic arms contorted by the gravity of the collision (green); a star forming complex left of center (blue); and dust (red).  In billions of years this mess might settle into a relatively normal looking galaxy.
Mercury: A Cratered Inferno (1999-01-02)
Mercury's surface looks similar to our Moon's. Each is heavily cratered and made of rock.  Mercury's diameter is about 4800 km, while the Moon's is slightly less at about 3500 km (compared with about 12,700 km for the Earth). But Mercury is unique in many ways.  Mercury is the closest planet to the Sun, orbiting at about 1/3 the radius of the Earth's orbit. As Mercury slowly rotates, its surface temperature varies from an unbearably cold -180 degrees Celsius to an unbearably hot 400 degrees Celsius. The place nearest the Sun in Mercury's orbit changes slightly each orbit - a fact used by Albert Einstein to help verify the correctness of his then newly discovered theory of gravity: General Relativity.  The above picture was taken by the only spacecraft ever to pass Mercury: Mariner 10 in 1974.
Orion's Horsehead Nebula (1999-01-03)
The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the black indentation to the red emission nebula seen just to the right of center of the above photograph. The bright star near the center is located in the belt of the familiar constellation of Orion. The horse-head feature is dark because it is really an opaque dust cloud which lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will alter its appearance. The emission nebula's red color is caused by electrons recombining with protons to form hydrogen atoms. Also visible in the picture are blue reflection nebulae, which preferentially reflect the blue light from nearby stars.
Ring Around the Cluster (1999-01-04)
It is difficult to hide a galaxy behind a cluster of galaxies.  The closer cluster's gravity will act like a huge lens, pulling images of the distant galaxy around the sides and greatly distorting them.  This is just the case observed in the above recently released image from the VLT.  The cluster CL2244-02 is composed of many yellow galaxies and is lensing the image of a blue-white background galaxy into a huge arc.  Careful inspection of the image will reveal at least one other lensed background galaxy appearing in red.  The foreground cluster can only create such a smooth arc if most of its mass is smoothly distributed dark matter - and therefore not concentrated in the yellow galaxies visible.  Analyzing these gravitational arcs gives astronomers a method to estimate the dark matter distribution in clusters of galaxies.
A New Jupiter Oval Rotates (1999-01-05)
ven Jupiter can do the twist.  Large cloud systems on Jupiter rotate, and the newly formed oval pictured above is no different.  This new oval formed earlier this year from the collision of two smaller ovals: an occurrence not unlike two large storms merging into one huge hurricane.  Even this new swirling storm, however, is small compared to Jupiter's Great Red Spot.  The above-animated frame dithers between two pictures of the new oval taken roughly an hour apart.  The Galileo spacecraft currently orbiting the giant Jovian planet captured the pictures.
M6: The Butterfly Cluster (1999-01-06)
To some, the outline of the open cluster of stars M6 resembles a butterfly.  M6, also known as NGC 6405, spans about 20 light-years and lies about 2,000 light years distant.  M6 can best be seen in a dark sky with binoculars towards the constellation of Scorpius, coving about as much of the sky as the full moon.  Like other open clusters, M6 is composed predominantly of young blue stars, although the brightest star is nearly orange.  M6 is estimated to be about 100 million years old.  Determining the distance to clusters like M6 helps astronomers calibrate the distance scale of the universe.
The Ring (1999-01-07)
cept for the Rings of Saturn, The Ring Nebula (M57) is probably the most famous celestial band. This planetary nebula's simple, graceful appearance is thought to be due to perspective -- our view from planet Earth looking straight into what is actually a barrel-shaped cloud of gas shrugged off by a dying central star. Astronomers of the Hubble Heritage Project produced this strikingly sharp image from Space Telescope observations using natural appearing colors to indicate the temperature of the stellar gas shroud. Hot blue gas near the energizing central star gives way to progressively cooler green and yellow gas at greater distances with the coolest red gas along the outer boundary. Dark, elongated structures can also be seen near the nebula's edge. The Ring Nebula is about one light-year across and 2,000 light-years away in the northern constellation Lyra.
Invader From Earth (1999-01-08)
These technicians are working on the solar-paneled Mars Polar Lander - yet another robotic spacecraft scheduled to invade the red planet. Mars Polar Lander is part of a series of missions focusing on a search for evidence of past or present life. Successfully launched atop a Delta II rocket on January 3rd, it should be the first to make a soft landing near Mars' South Pole. Its arrival is planned for December, springtime for the Martian Southern Hemisphere. Riding along are two separate microprobes intended to penetrate up to 2 meters beneath the soil in an attempt to directly determine if subsurface water ice is present. Mars Polar Lander will also carry another first to Mars ... a microphone.
Lunokhod: Moon Robot (1999-01-09)
On November 17, 1970 the Soviet Luna 17 spacecraft landed the first roving remote-controlled robot on the Moon. Known as Lunokhod 1, it weighed just under 2,000 pounds and was designed to operate for 90 days while guided in real-time by a five person team at the Deep Space Center near Moscow, USSR, Planet Earth. The futuristic looking eight wheeler rode on top of a descent module which extended ramps from both sides offering alternative routes to the surface in case one side was blocked by boulders. Lunokhod 1 actually toured the lunar Mare Imbrium (Sea of Rains) for 11 months in one of the greatest successes of the Soviet lunar exploration program. This Lunokhod's operations officially ceased on October 4, 1971, 14 years after the launch of Sputnik.
Venus' Once Molten Surface (1999-01-10)
If you could look at Venus with radar eyes - this is what you might see. This computer reconstruction of the surface of Venus was created from data from the Magellan spacecraft.  Magellan orbited Venus and used radar to map our neighboring planet's surface between 1990 and 1994. Magellan found many interesting surface features, including the large circular domes, typically 25-kilometers across, that are depicted above. Volcanism is thought to have created the domes, although the precise mechanism remains unknown. Venus' surface is so hot and hostile that no surface probe has lasted more than a few minutes.
Perihelion Sun (1999-01-11)
The Earth's orbit is not a perfect, sun-centered circle. At aphelion, the most distant point in Earth's orbit, the Sun is 150 million kilometers away and at perihelion, the closest point, Earth approaches the Sun to within about 147 million kilometers. While aphelion occurs in July, perihelion for planet Earth comes in January. In fact, inhabitants of the Northern Hemisphere, particularly those wearily weathering winter storms, may be surprised to learn that Earth reached its closest point to the Sun on January 3rd this year. This false-color picture recorded near perihelion is from the earth-orbiting Yohkoh Solar Observatory. It shows an increasingly active Sun in the light of X-rays. A negative color scheme is used, darker colors representing more intense X-ray light.
The Wind on Mars (1999-01-12)
Wind erosion has been discovered on Mars. Pictures of regions surrounding the north polar cap show sand dunes covered in frost.  In places, however, this frost has been eroded to uncover the dark sand underneath.  Since this frost can only be as old as the Martian winter is long, this erosion must have taken place within the past Martian year.  Once established, it is easy to visualize that much of the appearance of the above region has been sculpted by wind blown dust. Because the Martian atmosphere is so thin, a person standing on Mars would not get blown over by these Martian winds.
Sagittarius Star Cloud (1999-01-13)
Stars come in all different colors. The color of a star indicates its surface temperature, an important property used to assign each star a spectral type. Most stars in the above Sagittarius Star Cloud are orange or red and relatively faint, as our Sun would appear. The blue and greenish stars are hotter, many being relatively young and massive.  The bright red stars are cool Red Giants, bloated stars once similar to our Sun that have entered a more advanced stage of evolution.  Stars of the Sagittarius Cloud lie towards the center of our Galaxy - tantalizing cosmic jewels viewed through a rift in the dark, pervasive, interstellar dust. This famous stellar grouping houses some of the oldest stars known.
Crosby Ramsey Memorial Observatory Refractor (1999-01-14)
The Massachusetts-based firm of Alvan Clark and Sons became famous for making telescope optics near the end of the last century. Near the end of this century, major astronomical observatories still boast of telescopes with lenses and mirrors made by them including Lowell Observatory's 24 inch diameter refractor, the United States Naval Observatory's 26 inch refractor, the McCormick Observatory's 26 inch, Lick Observatory's 36 inch, and Yerkes Observatory's 40 inch refractor - the largest refracting telescope in the world. Small observatories too can claim such a link to telescopic history and many offer the general public a chance to "look through a classic". This gorgeous, completely refurbished 8 inch refractor was originally bought from Alvan Clark and Sons in 1927. On Thursdays it stargazes from the Crosby Ramsey Memorial Observatory dome atop the Maryland Science Center near Baltimore's Inner Harbor.
Reflections Of Orion (1999-01-15)
The Orion Nebula and its surroundings present skygazers with a wondrous jumble of newborn stars, gas, and dust. Emission nebulae - glowing energized clouds of gas, and reflection nebulae - dust clouds shining by reflected starlight, abound at this photogenic cosmic location a mere 1,500 light-years or so away. This telescopic image reveals an intriguing nebulosity which seems to consist of dust clouds illuminated not by starlight but by the light of the Orion Nebula itself. In non-telescopic views, the bright group of stars near the top appear as the northernmost star in Orion's sword. They are seen here illuminating the nearby dust clouds. Yet the yellowish streamers of dust across the middle reflect the light of the Orion Nebula, which lies just off the bottom edge of the photo.
Spiral Eddies On Planet Earth (1999-01-16)
Can you identify this wispy stellar nebula? How many light-years from Earth did you say? Resembling a twisting cloud of gas and dust between the stars this swirling form is actually close by - a spiral eddy formed near the North Atlantic Gulf Stream off the East coast of the U. S. Tens of miles across, spiral eddies are an ocean current phenomenon discovered by observations from manned spacecraft. Imaged by the Challenger space shuttle crew during the STS 41G mission this eddie is dramatically visible due to the low sun angle and strong reflection of sunlight. The reflection is caused by a very thin biologically produced oily film on the surface of the swirling water. Prior to STS 41G these eddies were thought to be rare but are now understood to be a significant dynamic feature of ocean currents. However, no good explanation of their origin or persistence exists.
NGC 1818: A Young Globular Cluster (1999-01-17)
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 perhaps 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. But things are different next door - in the neighboring LMC galaxy. Pictured above is a "young" globular cluster residing there: NGC 1818. Recent observations show it formed only about 40 million years ago - just yesterday compared to the 12 billion year ages of globular clusters in our own Milky Way
Kitt Peak National Observatory (1999-01-18)
At the top of Kitt Peak Mountain near Tucson, Arizona lies one of the world's great collections of telescopes.  As pictured, in the dome at the far left lies the 3.5-meter WIYN Telescope, famous recently for tracking distant supernovae.  The next major dome to the right houses a 36-inch telescope now used mostly for imaging.  Farther to the right beside a thin tower is a 2.1-meter Telescope used currently for imaging and spectroscopy.  The unusual triangular building houses the McMath-Pierce Solar Telescope. In front of it lies the Vacuum Tower Telescope while in back are the Burrell-Schmidt Telescope and the SARA 0.9-meter automated telescope.  At the far right lies one of the world's largest telescopes: the 4-meter Mayall Reflector.  Kitt Peak recently celebrated its 40th year during which it helped establish the existence of dark matter and the first gravitational lens.  Kitt Peak National Observatory is part of the United States' National Optical Astronomical Observatories and is operated under agreement with the National Science Foundation.
Telescope with Lightning (1999-01-19)
Telescopes are not very useful during lightning storms.  Nevertheless, with lightning illuminating a dark landscape, the picturesque dome of the famous Kitt Peak 2.1-meter Telescope makes for a dramatic photograph.  A passing car created the red and yellow streaks visible in the foreground. The 2.1-meter Telescope has participated in many important astronomical discoveries including the discovery of the Lyman-alpha forest, the first gravitational lens, and the first pulsating white dwarf.
Possible Planets And Infrared Dust (1999-01-20)
These near-infrared Hubble images of dust surrounding young stars offer the latest tantalizing evidence for planets beyond our Solar System. At left, the dark gap seen in the dust disk is reminiscent of a similar large gap in Saturn's rings believed to be sculpted by orbiting moons. By analogy, the gap in the dust disk of HD 141569 may be a larger scale result of unseen orbiting planets. At right is a relatively thin stellar dust ring suggestive of planetary rings held in place by orbiting moons. On a much larger scale this ring around the star HR 4796A could also indicate the presence of orbiting planet-sized bodies too faint to be directly visible. For a distance comparison, the orbit of Neptune is drawn at the lower right of each picture. The overwhelmingly bright starlight at the center has been blocked out to reveal the dim dust features.
Spiral Galaxy NGC 253 (1999-01-21)
A camera with over 67 million pixels (digital picture elements) was used to record this stunning image of spiral galaxy NGC 253.  Known as the Wide Field Imager (WFI), the camera is the latest instrument to be installed at the European Southern Observatory's 2.2 meter telescope in La Silla, Chile. Constructed from exposures made by the WFI in December 1998, this picture has been cropped from the full field to emphasize the galaxy and contrast adjusted to follow the graceful, winding arms and dramatic dust lanes of this photogenic island universe. Relatively bright foreground stars produce the sharp vertical streaks seen here while higher resolution versions of the image show intriguing, faint, background galaxies and likely globular star clusters associated with NGC 253. Two faint satellite trails are also visible. NGC 253, an Sc type spiral, is about 8 million light-years away in the southern constellation Sculptor.
Pegasus dSph: Little Galaxy of the Local Group (1999-01-22)
The Pegasus dwarf spheroidal galaxy (Peg dSph) is a small, newly recognized member of the Local Group of Galaxies. Likely a satellite companion of the Local Group's dominant player, the large spiral Andromeda (M31), the Pegasus dwarf galaxy is almost hidden in the glare of relatively bright foreground stars in our own Milkyway. Still, this dramatic Keck telescope 3-color image reveals Peg dSph as a clump of fainter, bluer stars 2,000 or so light-years across. Excitement over discoveries of Peg dSph and other nearby dwarf galaxies reflects the fact that little galaxies may loom large in the process of galaxy evolution. They are thought to be the building blocks from which larger galaxies are constructed.