juliensimon/nasa-apod huggingface dataset:
Walking in Space (1996-06-15)

Pictured above is the first american astronaut to walk in space: Edward White. White is seen floating outside the Gemini 4 capsule in 1965. The term "spacewalk" is deceiving since astronauts do not actually walk - they float - usually without their feet touching anything solid. White was connected to the spaceship only by a thick tether. He carried a Hand-Held Self-Maneuvering Unit which expelled gas allowing him to move around. A maneuvering device is necessary in the free-fall of space since there is nothing (besides the spacecraft) to push off of to guide movements.
APOD is One Year Old Today (1996-06-16)

The first Astronomy Picture of the Day (APOD) appeared one year ago today. Pictured above are Robert Nemiroff (left) and Jerry Bonnell (right), engaged in creating the APOD web pages. APOD started over speculative conversations on the ultimate value of the World Wide Web. In our (current) view, the WWW is the closest thing yet to an "Encyclopedia of Humanity," and we think it's important to contribute. We are proud to say that APOD has now annotated most of the famous astronomical pictures of our time and has made them available to the general public in an indexed and searchable archive. During it's first year, APOD's main daily picture page has been served over one million times. But APOD's mission continues. As space science progresses more pictures, fresh insights, and new educative links become available. Therefore, so long as public interest and NASA support continue, APOD will continue. We thank all whose gracious e-mail are continually a source of encouragement.
The United States at Night (1996-06-17)

This is what the United States of America looks like at night! Can you find your favorite US city on this image? Surprisingly, city lights make this task quite possible. The above picture is actually a composite of over 200 images made by satellites orbiting the Earth. Scans were made by the USAF Defense Meteorological Satellite Program (DMSP) Operational Linescan System. The DMSP satellites continue to help in the understanding and prediction of weather phenomena as well as provide key information about population patterns, city light levels, and even rural forest fires.

Image credit: NOAA/
NGDC
DMSP 
Digital Archive
Seven Sisters Versus California (1996-06-18)

In the lower left corner, dressed in blue, is the Pleiades.  Also known as the Seven Sisters and M45, the Pleiades is one of the brightest and most easily visible open clusters on the sky. The Pleiades contains over 3000 stars, is about 400 light years away, and only 13 light years across. Surrounding the stars is a spectacular blue reflection nebula made of fine dust.  A common legend is that one of the brighter stars faded since the cluster was named. In the upper right corner, dressed in red, the California Nebula.  Named for its shape, the California Nebula is much dimmer and hence harder to see than the Pleiades. Also known as NGC 1499, this mass of red glowing hydrogen gas is about 1500 light years away.

Image credit: Dominique
Dierick and Dirk De la Marche
Aurora: Curtains in the Sky (1996-06-19)

Looking out over Lake Superior at dusk you see Venus (lower left) and ... curtains? Like an ant looking up at window curtains, aurora frequently appear as huge flowing light displays. These colorful, often spectacular phenomena are most frequently visible from locations near the Earth's poles. Aurora are caused by electrons from the solar wind funneling to Earth along magnetic field lines, and striking atoms and molecules in our atmosphere.  Auroral color is determined by which atmospheric ions are struck and recombine to form neutral atoms. Hourly updates of auroral sightings are posted to the WWW. It is still controversial whether aurora make any sound audible from the ground. If you think you have "heard an aurora," please report it!

Image credit: Michael Dolan 
(Michigan Tech.)
Apollo Sunrise (1996-06-20)

In November of 1969, homeward bound aboard the "Yankee Clipper" command module, the Apollo 12 astronauts took this dramatic photograph of the Sun emerging from behind the Earth.  From this distant perspective, part of the solar disk peers over the Earth's limb, its direct light producing the jewel like glint while sunlight scattered by the atmosphere creates the thin bright crescent. Today at 10:24 pm Eastern Daylight Time is the Summer Solstice. From an earthbound perspective, the solar disk will climb to its greatest northern declination marking the Northern Hemisphere's first day of Summer and creating the longest day -- with over 15 hours of daylight near latitude +40 degrees.
A Very Large Array of Radio Telescopes (1996-06-21)

Pictured above is one of the world's premiere radio astronomical observatories: The Very Large Array (VLA). Each antenna dish is as big as a house (25 meters across) and mounted on railroad tracks. The VLA consists of 27 dishes - together capable of spanning the size of a city (35 kilometers).  The VLA is the most sensitive  radio telescope ever, and, through interferometry, can resolve a golf ball-sized radio source 150 kilometers away (0.04 arcsec). The VLA is continually making new discoveries, including determining the composition of galaxies, passing comets, quasars, HII regions, and clusters of galaxies. The VLA is also used to receive the weak radio signals broadcast from interplanetary spacecraft. The VLA is located in New Mexico, USA. A significant upgrade of VLA's capabilities is planned.

Image credit: Sarah 
Winfrey
(U. Michigan), 
NRAO
North to the Moon's Pole (1996-06-22)

This image is from the voyage of the intrepid Galileo spacecraft as it passed above the Moon's north pole on its long journey to Jupiter. It was made over 60 years after Admiral Byrd became the first to fly over the Earth's north pole. Within a superposed frame of lattitude and longitude lines much of the Moon's familiar face, dominated by smooth dark mare, is brightly lit. Near the pole itself, the harsh shadows reveal a rugged, cratered lunarscape.
Tycho's Supernova Remnant in X-ray (1996-06-23)

How often do stars explode? By looking at external galaxies, astronomers can guess that these events, known as a supernovae, should occur about once every 30 years in a typical spiral galaxy like our MilkyWay. However, the obscuring gas and dust in the disk of our galaxy probably prevents us from seeing many galactic supernovae -- making observations of these events in our own galaxy relatively rare. In fact, in 1572, the revered Danish astronomer, Tycho Brahe, witnessed one of the last to be seen. The remnant of this explosion is still visible today as the shockwave it generated continues to expand into the gas and dust between the stars. Above is an image of the X-rays emitted by this shockwave made by a telescope onboard the ROSAT spacecraft. The nebula is known as Tycho's Supernova Remnant.
A View from Venus: Rift Valley (1996-06-24)

Color information from the Soviet Venera landers and radar data from the Magellan spacecraft were used to construct this striking perspective view of the Venusian landscape. (In this computer generated image, the vertical scale has been exagerated.) In the foreground is the edge of a rift valley created by faulting in the crust of Venus. The valley runs all the way to the base of Gula Mons, a 2 mile high volcano seen here on the right, some 450 miles in the distance. On the left is another volcano, Sif Mons. Using radar to pierce the dense clouds continuously shrouding the Face of Venus, Magellan was able to explore over 98% of the Venusian surface, revealing a a diverse and tantalizing topography.
A Star Forming Region in the LMC (1996-06-25)

Stars sometimes form in colorful ways.  Pictured above is a small region in the nearby LMC galaxy where stars are forming. After a star is born, it may do several things to energize its immediate neighborhood. It may develop a strong wind which pushes away nearby gas; it may be so hot and intense that emitted light boils away nearby dust and gas, and it may be so massive that it soon goes supernova and catapults its elements back to the interstellar medium. Astronomers study regions like this - named DEM192 - to better understand how these and other processes proceed. This picture is a composite of three separate photographs, each sensitive to only one specific color of light - a color that distinguishes a specific chemical element.
Happy Birthday Charles Messier: M1 (1996-06-26)

French astronomer Charles Messier was born on June 26, 1730. Inspired by childhood sightings of comets and a solar eclipse visible from his home town of Badonvillier, he became an astronomer and comet hunter who kept careful records of his observations. While hunting for comets in the skies above France he made a now famous list of the positions of about 100 fuzzy, diffuse looking objects which appeared at fixed positions in the sky. Although these objects looked like comets, Messier knew that since they did not move with respect to the background stars they could not be the comets he was searching for. These objects are now well known to modern astronomers to be among the brightest and most striking nebulae, star clusters, and galaxies. Objects on Messier's list are still referred to by their "Messier number". The first object in his catalog, M1 pictured above - also known as the Crab Nebula, was recorded during his search for the return of comet Halley in 1758. Messier died in his home in Paris in 1817.
Voyager's Preview of Galileo at Ganymede (1996-06-27)

NASA's robot spacecraft Galileo began its long voyage to Jupiter in October of 1989. In December of last year it arrived in the Jovian system, beginning its unprecedented, detailed exploration by dropping a probe into the gas giant's atmosphere. By early this morning it will have accomplished another milestone in its ambitious mission. Now in orbit around Jupiter, Galileo will make its first close flyby of Ganymede, Jupiter's (and the solar system's) largest moon at 2:29 a.m. EDT. As planned, approaching to within 524 miles, it will make a series of high resolution images of the surface which will reveal features as small as 33 feet across. This close-up color image from the Voyager 2 flyby in 1979 previews sights Galileo will see in greater detail. Showing features as small as 3 miles across, it reveals a variety of terrain on Ganymede's icy surface, including impact craters with bright rays and long strips of light grooved structures suggesting large scale motions of the frozen crust. Galileo's flyby images will be stored onboard for playback and should be available during the week of July 10.
A Distant Galaxy in the Deep Field (1996-06-28)

Researchers believe that the faint reddish smudge indicated by the arrow in the image above is a candidate for the most distant known galaxy which may have existed only a few hundred million years after the Big Bang. The image is part of the Hubble Deep Field, the Hubble Space Telescope's deepest yet picture of the Universe. Made in December 1995 by staring for ten consecutive days with the Hubble, astronomers have been intently studying the resulting deep field image filled with remote galaxies for clues to what galaxies and the Universe looked like in the distant past. While nearby galaxies are easily detected in the image - some seen here have visible elliptical and even spiral structures - the most distant (and therefore oldest) galaxies must be identified by examining their appearance in different wavelengths of light. Based on this technique, six of the most distant galaxies in the Deep Field appear to be farther away than even quasars.
The Voyagers' Message in a Bottle (1996-06-29)

Launched in the summer of 1977, NASA's Voyager 1 and 2 spacecraft are now over 4.5 billion miles from the Sun. Still operational, the Voyagers are being tracked and commanded through the Deep Space Network. Having traveled beyond the outer planets, these remarkable spacecraft are only the third and fourth human built artifacts to escape our solar system, following in the footsteps of Pioneer 10 and 11. A 12-inch gold plated copper disk (pictured) containing recorded sounds and images representing human cultures and life on Earth, is affixed to each Voyager - a message in a bottle cast into the cosmic sea. The recorded material was selected by a committee chaired by Carl Sagan of Cornell University. The disks are intended to be played like a phonograph record at 16 and 2/3 revolutions per second. Cartridge and needle are supplied, along with some simple diagrams (visible above) which represent symbolically the spacecraft's origin and instructions for playing the disk. The exotic construction of the disks should provide them with a long lifetime as they coast through interstellar space. The two spacecraft will not make a close approach to another planetary system for at least 40,000 years.
Greetings from the Pioneers (1996-06-30)

Launched in the early 1970s Pioneer 10 and 11 were appropriately named - becoming the first spacecraft to travel through the asteroid belt, first to fly by Jupiter and Saturn, and the first human artifacts to venture beyond the solar system. Now coasting through interstellar space, they carry with them greetings in the form of a gold anodized plaque with symbolic drawings as illustrated above. The male and female figures are drawn to the same scale as the Pioneer spacecraft shown behind them. Immediately to the left is a map of the position of the sun with respect to nearby pulsars and the center of the galaxy while below is a drawing of the solar system indicating the planet of origin. In the upper left is a schematic of two fundamental states of the hydrogen atom. These diagrams along with other details of the plaque were designed by Carl Sagan of Cornell University and are intended to be decipherable by spacefaring extraterrestrial civilizations.
Worlds of a Distant Sun: 47 Ursae Majoris b (1996-07-01)

Within the last few years, observational astronomy has given humanity evidence of the existence of worlds beyond the solar system. Indeed, solar-type stars are now inferred to harbor planets of approximately Jupiter mass - some residing in temperature zones which could conceivably support liquid water and therefore life! Above is a hypothetical scene near one such planet whose sun, 47 Ursae Majoris (47 UMa), is a yellow dwarf star (spectral class G0 V) very similar to our own. In our sky, it appears as a faint, inconspicuous star below the cup of the northern hemisphere asterism, "the Big Dipper". (Our own sun would be equally inconspicuous when viewed from 47 UMa ...) Astronomer's G. Marcy and P. Butler announced the discovery of a planet associated with this star in 1996 and reported it to have a mass of about 2.4 Jupiters or more with an orbital period of 3 years. This artist's vision pictures the detected planet, referred to as 47 UMa b, as a gas giant surrounded by a ring of material - analogous to our own gas giant Saturn. In the foreground lies a hypothetical moon of 47 UMa b.  Could such a moon support life? 47 UMa is only 44 light years distant, fairly close by astronomical standards - yet there is evidence for planetary systems which are closer still. NASA plans to explore nearby planetary systems using spaceborne observatories.   APOD News: RJN to MTU

Image credit: John Whatmough,
Extrasolar Visions
NASA's Latest Rockets: X-33 (1996-07-02)

What will NASA rockets look like in the future?  Today's announcement gave one indication. Today Vice- President Al Gore announced that the Lockheed Martin Corporation will work with NASA to produce a reusable rocket with a remote pilot. Currently designated the X-33 program, the flight demonstration rocket design will utilize only a single stage, cost relatively little per launch, and be ready for re-launch within days. It is expected that an X-33 type rocket will be in use by NASA by the the year 2000. Pictured above is an artistic depiction of the candidate vehicle.    APOD News: RJN to MTU
Superbubbles in the LMC (1996-07-03)

Why is there a hole in the center of this nebula? A leading explanation is that it is caused by the stellar winds from the stars that live there. Stars - including the Sun - expel electrons, protons, and other charged ions in a steady stream - the stellar wind. The wind ions push out the normal hydrogen and helium gas found glowing in the nebula. This star forming region is located in the Large Magellanic Cloud. This picture is a composite of three separate photographs, each sensitive to only one specific color of light - a color that distinguishes a specific chemical element.  It is currently not known why stars emit a stellar wind.

Image credit: C. Smith
(U. Michigan), 
Curtis 
Schmidt Telescope, 
CTIO, 
Chile
The Cat's Eye Nebula (Revisited) (1996-07-04)

Three thousand light years away, a dying star throws off shells of glowing gas. This image from the Hubble Space Telescope reveals "The Cat's Eye Nebula" to be one of the most complex planetary nebulae known. In fact, the features seen in this image are so complex that astronomers suspect the bright central object may actually be a binary star system. The term planetary nebula, used to describe this general class of objects, is misleading. Although these objects may appear round and planet-like in small telescopes, high resolution images reveal them to be stars surrounded by cocoons of gas blown off in the late stages of stellar evolution.   APOD News: Policy on Re-Running Pictures
The Mysterious Rings of Supernova 1987a (1996-07-05)

What's causing those odd rings in supernova 1987a?  In 1987, the brightest supernova in recent history occurred in the Large Magellanic Clouds. At the center of the picture is an object central to the remains of the violent stellar explosion. When the Hubble Space Telescope was pointed at the supernova remnant in 1994, however, curious rings were discovered. The origins of these rings still remains a mystery. Speculation into the cause of the rings includes  beamed jets emanating from a dense star left over from the supernova, and a superposition of two stellar winds ionized by the supernova explosion.
Edmond Halley's Greatest Discoveries (1996-07-06)

Sir Edmond Halley was quite a discoverer.  Born in 1656, he computed in 1705 that a bright comet was periodic and would make another appearance in 1758. The comet appeared as predicted and is now known as Comet Halley. Unfortunately, Halley died in 1742 and never saw his prediction come true. In 1716  Halley proposed two types of diving bells that would enable people to explore the deep sea.  Halley pioneered our understanding of trade winds, tides, cartography, naval navigation, mortality tables, and stellar proper motions.  Halley (incorrectly) proposed that the Earth was made of concentric spheres the size of the inner planets each of which might contain life. Perhaps Halley's greatest discovery, however, was that his contemporary Isaac Newton had discovered a powerful mathematical formulation of gravity.
Isaac Newton Explains the Solar System (1996-07-07)

Sir Isaac Newton changed the world. Born in 1643, Newton was only an above-average student. But he went home from Cambridge one summer in 1665, thought a lot about the physical nature of the world, and came back two years later with a revolutionary understanding of mathematics, gravitation, and optics. A Professor of his, upon understanding what Newton had done, resigned his own position at Cambridge so Newton could have it. Newton's calculus provided a new mathematical framework for the rapid solution of whole classes of physical problems.  Newton's law of gravitation explained in one simple formula how apples fall and planets move.  Newton's insights proved to be so overwhelmingly powerful he was the first scientist ever knighted.
M33: The Triangulum Galaxy (1996-07-08)

The spiral galaxy M33 is a mid-sized member of our Local Group of galaxies. M33 is also called the Triangulum Galaxy for the constellation in which it resides. About four times smaller (in radius) than our Milky Way Galaxy and the Andromeda Galaxy (M31), it is much larger than the many of the local dwarf spheroidal galaxies. M33's proximity to M31 causes it to be thought by some to be a satellite galaxy of this more massive galaxy. M33's proximity to our Milky Way galaxy causes it to appear more than twice the angular size of the full moon, and visible with a good pair of binoculars.  In the above picture, visible light is shown in red and ultraviolet light superposed in blue.  Stars in M33 are the most distant ever to be studied spectroscopically.
M74: A Grand Design Spiral Galaxy (1996-07-09)

M74 is about the same size as our own Milky Way Galaxy. Like our Milky Way, M74 is classified a spiral galaxy. M74's sweeping lanes of stars and dust combined with its small nucleus make it a classic Grand Design Spiral. On the Hubble Sequence of Galaxies, M74 is listed as "Sc". In the above picture, visible light is shown in red and ultraviolet light superposed in blue. In general, older stars are more red and younger stars are blue. Studies with the Ultraviolet Imaging Telescope show that the disk of M74 has undergone significant star formation in just the past 500 million years.
Galileo Photographs Ganymede (1996-07-10)

Ganymede's surface is slowly being pulled apart. This photo of Ganymede was released earlier today by the Galileo team at NASA. The Galileo Spacecraft arrived at Jupiter in December 1995. In late June, the spacecraft passed within 10,000 kilometers of Ganymede's icy surface, and took pictures showing complex surface details for the first time. The line-like features in this photo are sunlit ridges rising above Ganymede's ice-plains.  The circular features are impact craters. Ganymede is the largest moon of Jupiter and hence the largest of the four Galilean satellites: Io, Europa, Ganymede, and Callisto.   APOD's Archive of Galileo at Ganymede
Ganymede: A Really Groovy Moon (1996-07-11)

Ganymede's surface is a wrinkled mess. As large ice-sheets shift on the moon's surface, parts of the surface buckle causing high ridges, deep furrows, and parallel grooves. This photo, taken by the Galileo spacecraft currently orbiting Jupiter, was released yesterday. The large circular feature near the picture bottom is a large impact crater. The impact that caused this large crater also caused the strange dark ejecta seen to the crater's right. The Sun illuminates the scene from the lower left. The Galileo spacecraft has also just discovered that Ganymede has a region of orbiting charged particles called a magnetosphere - a first for any moon. How Ganymede is able to generate a magnetosphere is a mystery.   APOD's Archive of Galileo at Ganymede
Ancient Cratered Plains on Ganymede (1996-07-12)

The largest moon in the Solar System shows regions that are ancient and battered. The high density of craters demonstrate that patches of Ganymede are indeed billions of years old. This photo is one of a series released by NASA two days ago from the Galileo spacecraft orbiting Jupiter. The large impact crater on the left is 19 kilometers across, while dark indentations in Ganymede's crusty surface-ice run diagonally.  Ganymede is composed of half rock and half water-ice. The Galileo spacecraft will continue to orbit Jupiter over the next 16 months and send back data about Jupiter and its four largest moons: Io, Europa, Ganymede, and Callisto.   APOD's Archive of Galileo at Ganymede