omnianasa/nasa-apod-metadata huggingface dataset:
X-Ray Pulsar (1998-07-23)
This dramatic artist's vision shows a city-sized neutron star centered in a disk of hot plasma drawn from its enfeebled red companion star. Ravenously accreting material from the disk, the neutron star spins faster and faster emitting powerful particle beams and pulses of X-rays as it rotates 400 times a second. Could such a bizarre and inhospitable star system really exist in our Universe? Based on data from the orbiting Rossi X-Ray Timing Explorer (RXTE) satellite, research teams have recently announced a discovery which fits this exotic scenario well - a "millisecond" X-ray pulsar. The newly detected celestial X-ray beacon has the unassuming catalog designation of SAX J1808.4-3658 and is located a comforting 12,000 light years away in the constellation Sagittarius. Its X-ray pulses offer evidence of rapid, accretion powered rotation and provide a much sought after connection between known types of radio and X-ray pulsars and the evolution and ultimate demise of binary star systems.
Alan B. Shepard Jr. 1923-1998 (1998-07-24)
On another Friday (May 5, 1961), at the dawn of the space age, NASA controllers "lit the candle" and sent Alan B. Shepard Jr. arcing into space atop a Redstone rocket. The picture shows the pressure-suited Shepard before the launch in his cramped space capsule dubbed "Freedom 7" . This historic flight - the first spaceflight by an American - made Shepard a national hero. Born in East Derry, New Hampshire on November 18, 1923, Shepard graduated from the United States Naval Academy in 1944 and went on to train and serve as a Naval Aviator. Chosen as one of the original seven Mercury Program astronauts, he considered this first flight the greatest challenge and actively sought the assignment. Shepard's accomplishments in his career as an astronaut spanned a remarkable period in human achievement and in 1972 he walked on the moon as commander of the Apollo 14 mission. A true pioneer and intrepid explorer, Alan Shepard died Tuesday at age 74 after a lengthy illness.
Hawaii (1998-07-25)
Aloha! With the graceful arc of the Earth's limb in the background, the Hawaiian Island archipelago is visible in this stunning photo taken by the astronauts onboard the shuttle Discovery in October of 1988. Along with popular beaches and tropical resorts, these volcanic islands offer extreme elevations with dark, dry, cloudless skies. Consequently they have also become popular sites for large and sophisticated ground based telescopes. The peak of Mauna Kea, on the Big Island (upper left), boasts an impressive array of astronomical instruments including the Keck, the Canada-France-Hawaii Telescope, the NASA IRTF, the JCMT and UKIRT, and the Gemini Telescope Project. The dormant volcanic cone of Haleakala on Maui (just below the Big Island) is home to the Air Force Maui Optical Station and the Mees Solar Observatory. Mahalo nui loa!
Antares (1998-07-26)
Antares is a huge star. In a class called red supergiant, Antares is about 700 times the diameter of our own Sun, 15 times more massive, and 10,000 times brighter.  Antares is the brightest star in the constellation of Scorpius and one of the brighter stars in all the night sky.  Antares is seen surrounded by a nebula of gas which it has itself expelled. Radiation from Antares' blue stellar companion helps cause the nebular gas to glow, as photographed above.  Antares is located about 500 light years away.
N81: Starbirth in the SMC (1998-07-27)
A very young star cluster has been discovered in a neighboring galaxy.  The stars found in this cluster, dubbed N81, are so young and massive that they furiously eject matter and light up the surrounding nebula.  The ejected stellar winds combine and interact to sculpt beautiful and complex structures.  Visible near the center of the above representative-color picture are two of N81's brightest stars. Just above them lies a dark knot of dust and gas where these massive stars probably originated.  The home galaxy of this stellar nursery is the Small Magellanic Cloud (SMC) located about 200,000 light-years away.
Impact on Jupiter (1998-07-28)
In 1993, a strange string of comet pieces was discovered near the planet Jupiter. So unusual a sight, Comet Shoemaker-Levy 9 (SL9) quickly became the object of much scientific curiosity.  Studies showed that the Sun would soon perturb the orbit of SL9 so that it would actually strike Jupiter in July 1994.  The studies were right. The above picture shows the impact site of SL9's fragment G on Jupiter's cloud-tops.  The size of the dark outer ring is roughly the size of the Earth.  Since Jupiter is mostly gas, the comet melted and evaporated before plunging too far into Jupiter's atmosphere.
The High Energy Heart Of The Milky Way (1998-07-29)
These high resolution false color pictures of the Galactic center region in high energy X-ray and gamma-ray light result from a very long exposure of roughly 3,000 hours performed from 1990 to 1997 by the French SIGMA telescope onboard the Russian GRANAT spacecraft. Each image covers a 14x14 degree field which includes most of the central bulge of our Milky Way Galaxy. The X-ray picture (left) reveals a cluster of sources releasing enormous amounts of energy. They are probably binary star systems where matter accretes onto a collapsed object, either a neutron star or a black hole. But according to recent theories, only those binary systems with black holes can radiate above X-ray energies -- in the gamma-ray regime. In that case, the SIGMA sources also shining in the gamma-ray picture (right) betray the presence of accreting stellar black holes! Surprisingly, no high energy source seems to coincide exactly with the Galactic center itself, located near the brightest source at the bottom of both pictures. This indicates that the large black hole thought to be lurking there is unexpectedly quiet at these energies.
Volcanos on Mars: Elysium Region (1998-07-30)
This "synthetic color" image swath of the Elysium Volcanic Region of Mars was recorded by Mars Global Surveyor's wide angle camera on July 2. North is up and the sun illuminates the scene from the lower right. Bright clouds hover near the northern most dome-shaped volcano Hecates Tholus. The shield volcano Elysium Mons lies about 250 miles south near the image center, and farther south lies another dome-shaped volcano, Albor Tholus, with a broad summit basin or caldera. Even though Mars is just half the size of planet Earth, it is known for its volcanos - the largest of which dwarf their terrestrial counterparts.
IRAS Orion (1998-07-31)
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 InfraRed Astronomical Satellite (IRAS). It combines information recorded at three different invisible infrared wavelengths in a red, green, and blue color scheme 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 purplish dot just above center. Immediately to the right of Betelgeuse and prominent in the IRAS skyview, expanding debris from a stellar explosion, a supernova remnant, is seen as a large bright ring-shaped feature. The famous gas clouds in Orion's sword glow brightly as the yellow regions at the lower right. No longer operational, IRAS used a telescope cooled by liquid helium to detect celestial infrared radiation.
A String Of Pearls (1998-08-01)
Comet Shoemaker-Levy 9, named after its co-discoverers, was often referred to as the "string of pearls" comet. It is famous for its suggestive appearance as well as its collision with the planet Jupiter! The comet's original single nucleus was torn to pieces by Jupiter's strong gravity during a close encounter with the solar system's largest planet in 1992. The pieces are seen in this composite of Hubble Space Telescope images to be "pearls" strung out along the comet's orbital path. In July of 1994 these pieces collided with Jupiter in a rare and spectacular series of events.
Galaxy Dwingeloo 1 Emerges (1998-08-02)
Sometimes you can't see the forest for the trees. But if you look closely at the center of the above photograph, you will see a whole spiral galaxy behind the field of stars. Named Dwingeloo 1, this nearby galaxy was only discovered recently (1994) because much of its light was obscured by dust, gas and bright stars of our own Milky Way Galaxy. In fact, all the individually discernible stars in the above photograph are in our Galaxy. Dwingeloo 1 turned out to be a large galaxy located only five times as distant as the closest major galaxy - M31.
M44: A Beehive of Stars (1998-08-03)
M44 is a prominent open cluster of stars. Nicknamed Praesepe and "The Beehive", it is one of the few open clusters visible to the unaided eye.  M44 was thought to be a nebula until Galileo used an early telescope to resolve the cluster's bright blue stars. These stars are visible in the above image. M44, which is thought to have formed about 400 million years ago, is larger and older than most other open clusters.  The Beehive Cluster lies about 580 light-years away, and spans about 10 light-years across.  When viewed with a powerful telescope, hundreds of stars become visible.
Jupiter Swallows Comet Shoemaker Levy 9 (1998-08-04)
What happens when a comet encounters a planet?  If the planet has a rocky surface, a huge impact feature will form.  A giant planet like Jupiter, however, is mostly gas.  When Comet Shoemaker-Levy 9 struck Jupiter in 1994, each piece was swallowed into the vast Jovian atmosphere.  Pictured above is a time-lapse sequence of the result of two fragments striking Jupiter. As the comet plunged in, it created large dark marks that gradually faded.  The high temperature of gas under Jupiter's cloud tops surely caused the comet fragment to melt before it plunged very far.  Because Jupiter is much more massive than any comet, the orbit of Jupiter around the Sun did not change noticeably.
Ganymede: Torn Comet - Crater Chain (1998-08-05)
This remarkable line of 13 closely spaced craters on Jupiter's moon Ganymede was photographed by the Galileo spacecraft in 1997. The picture covers an area about 120 miles wide and the chain of craters cuts across a sharp boundary between dark and light terrain. What caused this crater chain? During the exploration of the Solar System, crater chains like this one have been discovered in several places and were considered mysterious until a dramatic object lesson was offered by comet Shoemaker-Levy 9. In 1994 many denizens of planet Earth watched as huge pieces of this torn comet slammed into Jupiter itself in a spectacular series of sequential impacts. It is very likely that similar torn comets from the early history of the Solar System are responsible for this and other crater chains.
Infrared Horsehead (1998-08-06)
This famous cosmic dust cloud was imaged in infrared light by the European Space Agency's Infrared Space Observatory (ISO) satellite.  The false-color picture shows the bright infrared emission from dust and molecular gas in part of the Orion star forming region surrounding the Horsehead Nebula. In visible light, the horsehead-shaped dust cloud looks dark against a background of bright glowing gas. But in this image, the interstellar infrared glow engulfs much of the horse's head. Just above and to the right of center, only the top remains crowned by a bright, newborn star. The very bright object at the lower left is the reflection nebula NGC 2023, a dense concentration of interstellar gas and dust which is also associated with newly formed stars.
M65 Without Moth (1998-08-07)
Messier 65 (M65) is a bright spiral galaxy of stars only 35 million light-years away in the constellation Leo. With very tightly wound spiral arms, a large central bulge, and well defined dust lanes, this galaxy is a member of a group of galaxies known as the Leo triplet. The faint blue smudges along the spiral arms of M65 are large clusters of bright, newly formed stars within the distant galaxy while the bright individual stars are foreground objects in our own Milky Way galaxy. North is to the left in this composite of digital pictures taken using the large 4-meter (diameter) Mayall telescope at Kitt Peak National Observatory in the southwestern United States. The horizontal stripes are digital blemishes ... but the image has been adjusted to remove the blotch created by a moth which worked its way into the camera's filter wheel.
The Cygnus Loop (1998-08-08)
15,000 years ago a star in the constellation of Cygnus exploded -- the shockwave from this supernova explosion is still expanding into interstellar space! The collision of this fast moving wall of gas with a stationary cloud has heated it causing it to glow in visible as well as high energy radiation, producing the nebula known as the Cygnus Loop (NGC 6960/95). The nebula is located about 2500 light years away. The colors used here indicate emission from different kinds of atoms excited by the shock; oxygen-blue, sulfur-red, and hydrogen-green. This picture was taken with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope.
Shapley 1: An Annular Planetary Nebula (1998-08-09)
What happens when a star runs out of nuclear fuel? The center condenses into a white dwarf while the outer atmospheric layers are expelled into space and appear as a planetary nebula. This particular planetary nebula, designated Shapley 1 after the famous astronomer Harlow Shapley, has a very apparent annular ring like structure. Although some of these nebula appear like planets on the sky (hence their name), they actually surround stars far outside our Solar System.
Meteors Now and Again (1998-08-10)
The Perseid Meteor Shower, usually the best meteor shower of the year, will peak over the next two nights.  Over the course of an hour, a person watching a clear sky from a dark location might see as many as 100 meteors.  These meteors are actually specs of rock that have broken off Comet Swift-Tuttle and continue to orbit the Sun.  This year, however, the Perseids may only be second best.  In November the Earth is predicted to move through a denser stream of Comet Tempel-Tuttle debris, possibly causing greater than 10,000 meteors per hour visible at some locations.  Pictured above is the alpha-Monocerotid meteor outburst of 1995.  This is the last week to send your name to a comet with NASA's planned Stardust mission.
ERAST Pathfinder-Plus: Daedalus Defied (1998-08-12)
Daedalus warned Icarus that if he flew too high, the Sun would melt his wings.  Apparently, nobody gave the ERAST Pathfinder-Plus aircraft a similar warning.  Earlier this month, not only did Pathfinder-Plus fly higher than any previous propeller-driven aircraft - its wings converted sunlight into power. Pictured, Pathfinder-Plus is flying above Hawaii soon after soaring to a record height of 24,700 meters.  What's more, Pathfinder-Plus is only a prototype -- future aircraft in the ERAST program may fly higher. Pathfinder's wings spread nearly 30 meters, and its total mass is only about 270 kilograms.  NASA's Pathfinder-Plus is flown by remote control, and can stay aloft for weeks at a time.
The Moons Of Earth (1998-08-13)
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 its 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 orbits 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.
The Dunes Of Mars (1998-08-14)
The North Pole of Mars is ringed by a "sea of sand dunes". For Mars' Northern Hemisphere, Spring began in mid July and increased sunlight is now shrinking the polar cap revealing the wind-swept dunes to the cameras onboard the Mars Global Surveyor spacecraft. North is up in this recently released close-up which covers a region about 1.2 miles across at 77 degrees Northern Martian Latitude. These dunes have been formed by winds generally blowing from the Southwest and are still covered with scattered white patches of carbon dioxide frost. Near the end of January 1999 Summer will begin and offer even clearer views of Northern dunes of Mars.
The Perseus Cluster of Galaxies (1998-08-15)
Here is one of the largest objects that anyone will ever see on the sky. Each of the fuzzy blobs in the above picture is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. We view the cluster through the foreground of faint stars in our own Milky Way Galaxy. It takes light roughly 300 million years to get here from this region of the Universe, so we see this cluster as it existed before the age of the dinosaurs. Also known as Abell 426, the center of the Perseus Cluster is a prodigious source of X-ray radiation, and so helps astronomers explore how clusters formed and how gas and dark matter interact. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster of galaxies, which spans over 15 degrees and contains over 1000 galaxies.
Doomed Star Eta Carinae (1998-08-16)
Carinae may be about to explode. But no one knows when - it may be next year, it may be one million years from now.  Eta Carinae's mass - about 100 times greater than our Sun - makes it an excellent candidate for a full blown supernova. Historical records do show that about 150 years ago Eta Carinae underwent an unusual outburst that made it one of the brightest stars in the southern sky.  Eta Carinae, in the Keyhole Nebula, is the only star currently thought to emit natural LASER light. This image, taken in 1996, resulted from sophisticated image-processing procedures designed to bring out new details in the unusual nebula that surrounds this rogue star. Now clearly visible are two distinct lobes, a hot central region, and strange radial streaks. The lobes are filled with lanes of gas and dust which absorb the blue and ultraviolet light emitted near the center. The streaks remain unexplained. Will these clues tell us how the nebula was formed?  Will they better indicate when Eta Carinae will explode?
Comet Hyakutake and the Milky Way (1998-08-17)
Two years ago, the Great Comet of 1996, Comet Hyakutake, inched across our northern sky during its long orbit around the Sun. Visible above as the bright spot with the faint tail near the picture's center, Comet Hyakutake shares the stage with part of the central band of the Milky Way Galaxy, prominent in the picture's upper right. Also visible are Antares, the bright orange star in the upper right, Arcturus, the bright star on the lower left, and the Pipe Nebula, which is perhaps harder to find.  Comet Hyakutake's unusually close approach to the Earth allowed astronomers to learn many things, including that comets can emit much X-ray light.
APM 08279+5255: The Brightest Object Yet Known (1998-08-18)
It shines with the brightness of 100 billion Suns.  Is it a mirage? The recently discovered quasar labeled APM 08279+5255 has set a new record as being the brightest continuously emitting object yet known.  APM 08279+5255's great distance, though, makes it only appear as bright as magnitude 15.2, an object which can be seen with a moderate sized telescope.  It is the quasar's extreme redshift of 3.87 that places it far across our universe, and implies a truly impressive energy output.  One possible explanation of APM 08279+5255's record luminosity is that it is partly a mirage: its light is highly magnified by an intervening galaxy that acts as a  gravitational lens. Alternatively, APM 08279+5255 might be the most active known center of an intriguing class of colliding galaxies rich in gas and dust.
M13: The Great Globular Cluster in Hercules (1998-08-19)
M13 is one of the most prominent and best known globular clusters.  Visible with binoculars in the constellation of Hercules, M13 is frequently one of the first steps beyond the ordinary visible to the casual sky gazer.  M13 is a colossal home to over 100,000 stars, spans over 150 light years across, lies over 20,000 light years distant, and is over 12 billion years old.  At the 1974 dedication of Arecibo Observatory, a radio message about Earth was sent in the direction of M13.  The reason for the low abundance of unusual blue straggler stars in M13 is currently unknown.
SOHO Composite: Coronal Mass Ejection (1998-08-20)
This complex composite image of an ominous and spectacular event - an expanding storm of energetic particles from the Sun - was constructed using data recorded by the SOHO spacecraft on November 6, 1997. Four images from two SOHO (Solar Orbiting Heliospheric Observatory) instruments have been nested to show the ultraviolet Sun at center and a large eruption of material from the right-hand solar limb. Known as a Coronal Mass Ejection or CME, the expanding cloud has become relatively cool and dark in the middle with bright edges still connected to the solar surface. High energy protons have peppered the SOHO detectors causing the crazed streaks and blemishes. The picture covers a region extending about 13.5 million miles from the Sun (32 Solar Radii).  On June 25, after successfully completing its planned mission, contact with SOHO was lost -- but has recently been re-established! Hopefully SOHO will soon be able to continue operating in an extended mission phase.
A Massive Cluster In A Young Universe (1998-08-21)
Conventional theories suggest that this cluster of galaxies should not exist. Each fuzzy spot in this false-color Hubble Space Telescope image of the central regions of a newly discovered galaxy cluster is a galaxy similar in mass to our own Milky Way. The cluster is one of the most massive known, contains thousands of galaxies, and is a few million light-years across. But it is also 8 billion light-years distant and so formed when the Universe was only about half its present age. Ironically, if the total mass of the Universe is large, modern theories predict that clusters of galaxies as massive as nearby clusters should not have existed at such early times and great distances. One explanation for this cluster's presence is that the Universe we live in is not massive enough to eventually halt its expansion - contradicting some current standard views of cosmology.
Twistin' by the Lagoon (1998-08-22)
The awesome spectacle of starbirth produces extreme stellar winds and intense energetic starlight -- bombarding dusty molecular clouds inside the Lagoon Nebula (M8).  At least two long funnel shaped clouds, each roughly half a light-year long, have apparently been formed by this activity. They extend from the upper left of this close-up of the bright area of the Lagoon known as 'the Hour Glass'. Are these interstellar funnel clouds actually swirling, twisting analogs to Earthly tornados? It's possible. As energy from nearby young hot stars, like the one at lower right, pours into the cool dust and gas, large temperature differences in adjoining regions can be created generating shearing winds. This picture is a reprocessed HST image made in 1995 as researchers explored this nearby (5,000 light-year distant) starforming region which lies in the direction of Sagittarius.
Vega (1998-08-23)
Vega is a bright blue star 25 light years away. Vega is the brightest star in the Summer Triangle, a group of stars easily visible summer evenings in the northern hemisphere. The name Vega derives from Arabic origins, and means "stone eagle."  4,000 years ago, however, Vega was known by some as "Ma'at" - one example of ancient human astronomical knowledge and language.  14,000 years ago, Vega, not Polaris, was the north star. Vega is the fifth brightest star in the night sky, and has a diameter almost three times that of our Sun.  Life bearing planets, rich in liquid water, could possibly exist around Vega. The above picture, taken in January 1997, finds Vega, the Summer Triangle, and Comet Hale-Bopp high above Victoria, British Columbia, Canada.