juliensimon/nasa-apod huggingface dataset:
A String Of Pearls (1995-07-13)

July 13, 1995    A String Of Pearls  Picture Credit: NASA, Hubble Space Telescope (courtesy of H. Weaver)  Explanation:  Comet Shoemaker-Levy 9, named after its co-discoverers, was often referred to as the "string of pearls" comet. It is famous for its unusual 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 unique and spectacular series of events.  For more information about the picture see the Split Comet Studies Page.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
Comet Impacts on Jupiter (1995-07-14)

July 14, 1995    Comet Impacts on Jupiter  Picture Credit: NASA, Hubble Space Telescope  Explanation:  In July of 1994, pieces of Comet Shoemaker-Levy 9, also known as the "string of pearls" comet, collided with the planet Jupiter. As the comet fragments smashed in to Jupiter, the resulting explosions scattered large quantities of dusty cometary debris into the Jovian atmosphere. The clouds of debris created the multiple dark smudges visible in this picture. Jupiter's rotation causes the successive impact sites to be strung out along the cloud bands while the strong winds cause the appearance of the smudges to change with time. Jupiter's famous red spot is also visible to the left of center.  For more information about the picture see comments by the Hubble Space Telescope Comet Team.   We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
The Crater Chain (1995-07-15)

July 15, 1995    The Crater Chain  Picture Credit: NASA, Voyager Team  Explanation:  NASA's robot spaceprobe Voyager 1, took this closeup image of the surface of Jupiter's crater scarred moon Callisto in 1979. A mysterious chain of craters is seen to extend diagonally across the image (upper left to lower right). What could cause the craters to line up in such a regular fashion? Scientists were at a loss to explain this crater chain along with several other chain like features observed on Callisto's surface. Fifteen years later, with the discovery of Comet Shoemaker-Levy 9, also known as the "string of pearls" comet, the mystery was solved. Comets whose orbits stray too close to Jupiter are torn apart by the strong gravity. When the individual pieces, strung out along the orbital path of the comet hit an object like Callisto, the sequence of impacts produces a crater chain.  For more information about the picture see the Split Comet Studies Page.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
The Exploration of Mars (1995-07-16)

July 16, 1995    The Exploration of Mars  Picture Credit: NASA,Viking Project, USGS  Explanation:  Thirty years ago NASA's exploration of Mars began. In July of 1965 the Mariner 4 spacecraft flew within 6,000 miles of Mars and returned 21 pictures of the mysterious red planet. NASA's continued exploration of Mars has produced detailed views of the red tinged Martian surface like the one shown above which is a composite of 102 images from the Viking missions to Mars . The composite was constructed by the  US Geological Survey. For more information about the picture see the NSSDC Photo Gallery of Mars. The exploration of Mars is chronicled by the Center For Mars Exploration.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
Barsoom (1995-07-17)

July 17, 1995    Barsoom  Picture Credit: NASA,Viking Project  Explanation:  "Yes, I have been to Barsoom again ..." begins John Carter in Edgar Rice Burroughs' 1913 science fiction classic "The Gods of Mars". In Burroughs' novels describing Carter's adventures on Mars, "Barsoom" is the local name for the red planet. Long after Burroughs' stories were published, Mars has continued to capture the imagination of science fiction writers as a popular location for extraterrestrial adventures. This dramatic picture of a crescent Mars was taken by NASA's Viking 2 spacecraft in 1976.  For more information about Earth dwellers' efforts to explore Mars, see The Martian Chronicle.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
Cygnus Loop Supernova Shockwave (1995-07-18)

July 18, 1995    Cygnus Loop Supernova Shockwave  Credit: NASA, HST, WFPC2, Jeff Hester  Explanation:  15,000 years ago a star in the constellation of Cygnus exploded. This picture shows a portion of a shockwave from this  supernova explosion still expanding past nearby stars. The collision of this gaseous shockwave with a stationary gas cloud has heated the gas causing it to glow in a spectacular array of colors, known as the Cygnus Loop.  This picture was taken with the Wide Field and Planetary Camera 2 on board the  Hubble Space Telescope. For more information see the NASA Hubble Space Telescope  press release.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
The Mountains of Mars (1995-07-19)

July 19, 1995    The Mountains of Mars  Picture Credit: NASA,Viking Project  Explanation:  Volcanic activity on Mars has produced towering mountains. The largest one, Olympus Mons, is pictured here in this Viking Orbiter image. Olympus Mons is a shield volcano nearly 15 miles high and over 300 miles wide at its base. By comparison, Earth's largest volcano, Mauna Loa in Hawaii, is just over 5 miles high and about 12 miles wide.  For more information about volcanic mountains on Mars see Calvin J. Hamilton's Mars page. The exploration of Mars is chronicled by the Center For Mars Exploration.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
The Grand Canyon of Mars (1995-07-20)

July 20, 1995    The Grand Canyon of Mars  Picture Credit: NASA,Viking Project,USGS  Explanation:  The Mariner Valley, also known as the Valles Marineris canyon system, appears in this mosaic of images from NASA's Viking spacecraft as a huge gouge across the red planet. This "Grand Canyon" of Mars is about 2500 miles long and up to 4 miles deep. By comparison, the Earth's Grand Canyon is less than 500 miles long and 1 mile deep.  For more information about Mars see Calvin J. Hamilton's Mars Page.  The exploration of Mars is chronicled by the Center For Mars Exploration.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
The Search for Life on Mars (1995-07-21)

July 21, 1995    The Search for Life on Mars  Picture Credit: NASA,Viking Project,  Explanation:  Although images of Mars taken from space revealed the planet to have a barren and cratered surface, scientists did not give up the search for martian life. In 1976 NASA's Viking project succeeded in landing two robot probes on the surface of Mars. These landers were able to carry out sophisticated chemical experiments to look for signs of microscopic life in the martian soil. However, the experiments failed to produce any convincing evidence for life on Mars. Cameras onboard the Viking Landers also returned spectacular photos of the rocky martian landscape, like the one above, which showed no sign of martian animal or plant life.   For more information about the picture see The NSSDC Mars Photo Gallery. The exploration of Mars is chronicled by the Center For Mars Exploration.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
The Face on Mars (1995-07-22)

July 22, 1995    The Face on Mars  Picture Credit: NASA,Viking Project,  Explanation:  This image, showing what looks to be a human face sculpted on the martian surface, was produced using data from NASA's Viking 1 orbiter in 1976. Described in a press release as a "face-like hill" it caused some to offer the sensational speculation that it was an artificial construct built by an intelligent civilization on Mars! As a result, this image was splashed across the covers of many grocery store tabloids at the time. A detailed analysis of multiple images of this feature reveals a natural looking martian hill whose illusory face-like appearance depends on viewing angle and angle of illumination.  For more information about the picture see the NSSDC Photo Gallery of Mars. For a detailed discussion of the "Face on Mars" see Calvin J. Hamilton's Face on Mars page.  We keep an archive of Astronomy Pictures of the Day.   Astronomy Picture of the Day is brought to you by  Robert Nemiroff and  Jerry Bonnell . Original material on this page is copyrighted to Robert J. Nemiroff and Jerry T. Bonnell.
M20: The Trifid Nebula (1995-07-23)

July 23, 1995    M20: The Trifid Nebula  Credit: Hopkins Observatory, Karen Gloria   Explanation:  The vivid blue and violet colors present in the Trifid Nebula result from the abundance of young stars there. The light from young massive stars is quite blue and has the ability to remove electrons from surrounding gas. When these electrons re-combine with the gas, radiation rich in blue and violet light is emitted. Some of the nebula's light also results from the reflection of star light off of extremely small carbon specks known as 'dust'.  This object is known to astronomers as M20 - the twentieth object on Charles Messier's list of diffuse sky objects.  This image was taken with a 6-inch refracting telescope.  For more information on M20 see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
M31: The Andromeda Galaxy (1995-07-24)

July 24, 1995    M31: The Andromeda Galaxy  Credit: The Electronic Universe Project   Explanation:  Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image  are actually stars in our Galaxy that are well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about 2 million years for light to reach us from there.  For more information on M31 see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
M1: The Crab Nebula (1995-07-25)

July 25, 1995    M1: The Crab Nebula  Credit: The Electronic Universe Project   Explanation:  In the year 1054 a star in the constellation of Taurus exploded in a spectacular supernova so bright it appeared to dominate the sky except for the Sun and Moon for many days.  It left behind one of the most brilliant nebulae, listed first in Charles Messier's list of nebulous sky objects. Today we know that the center of the nebula houses the remnant of the explosion: a spinning neutron star called a pulsar.  The Crab pulsar is visible in almost every part of the electromagnetic spectrum, and has been a useful astronomical tool. It is still unclear how the the pulsar emits the light that we see.   For more information on M1 see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
M15: A Great Globular Cluster (1995-07-26)

July 26, 1995    M15: A Great Globular Cluster  Credit: The Electronic Universe Project   Explanation:  A globular cluster is a system of about one million stars that together orbit a galaxy. One of the brightest globular clusters in our Milky Way galaxy is the pictured M15, the fifteenth object on Messier's list of diffuse objects on our sky. Most stars in globular clusters are older and redder than our Sun, which is about 5 billion years old.  For more information on M15 see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
M57: The Ring Nebula (1995-07-27)

July 27, 1995    M57: The Ring Nebula  Credit: The Electronic Universe Project, Nelson Caldwell  Explanation:  A star with mass similar to that of our Sun will throw off its outer gasses after fusion has stopped in its core. Possibly the most visually spectacular of these planetary nebula is the pictured Ring Nebula. The appearance as a ring is really an illusion of projection - the nebula is actually a spherical shell. At the center a blue dot is visible which is the old core of the star, known as a white dwarf. It is still not known exactly how the star throws off the gas that becomes the nebula.   For more information on the Ring Nebula see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
M82: An Irregular Galaxy (1995-07-28)

July 28, 1995    M82: An Irregular Galaxy  Credit: The Electronic Universe Project  Explanation:  Not all galaxies have spiral structure like our Milky Way. Many have smooth elliptical shapes, but also many have irregular shapes such as the bright sky object M82, the 82nd object on Messier's list. The strange structure of this galaxy is thought to be caused by young stars ejecting gas in energetic bubbles, and by lanes of absorbing dust. For more information on M82 see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
M27: The Dumbbell Nebula (1995-07-29)

July 29, 1995    M27: The Dumbbell Nebula  Credit: The Electronic Universe Project, Karen Gloria  Explanation:  The Dumbbell Nebula is a beautiful red and blue planetary nebula in the constellation of Vulpecula. It is the 27th object on Charles Messier's list of diffuse sky objects, and so is referred to as M27.  Its high surface brightness makes it a good target for small telescopes. 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, astronomers have determined them to be stars surrounded by cocoons of gas blown off in the late stages of evolution.   For more information on M27 see The Electronic Universe Project's  write-up. Many images of Messier objects can be found in The Electronic Universe Project's The Galaxy Gallery: Messier Objects.
The Rings of Saturn (1995-07-30)

July 30, 1995    The Rings of Saturn  Credit: NASA, Jet Propulsion Laboratory, Voyager Project  Explanation:  Saturn's spectacular system of bright rings has been the subject of study and wonder since Galileo first turned his telescope on the ringed planet in 1610. To Galileo, the blurry image produced by his small telescope was confusing. Saturn appeared to him to have "ear-like" appendages which he thought might be large moons. Eventually, larger telescopes revealed the incredible truth - Saturn was surrounded by bright rings. The image above, made by NASA's Voyager 2 spacecraft, further reveals the intricate structure of the ring system. The image has been computer enhanced and color coded to bring out the subtle details. For more information about the picture see the NASA, JPL press release .
Exploring Saturn's Rings (1995-07-31)

July 31, 1995    Exploring Saturn's Rings  Credit: NASA, Jet Propulsion Laboratory, Voyager Project  Explanation:  By watching a star flicker and fade as it passed behind Saturn's rings, NASA's Voyager 2 spacecraft was able explore the ring system in amazing detail. Data produced by Voyager's instruments as the star Delta Scorpii was occulted by some of the outer rings was used to reconstruct this image which shows details almost 1000 times smaller than normally possible with Voyager's cameras.  For more information about the picture see the NASA, JPL press release .
Crossing The Ring Plane (1995-08-01)

August 1, 1995    Crossing The Ring Plane  Credit: NASA, Hubble Space Telescope  Explanation:  "I do not know what to say in a case so surprising, so unlooked for and so novel." announced Galileo when Saturn's rings appeared to vanish in 1612. In fact, every 15 years Saturn's rings seem to almost disappear as viewed from the Earth. This happens just as the orbiting Earth crosses the plane of Saturn's rings. The edge on perspective temporarily robs astronomers of a spectacular sight, however, the ring plane crossing affords them the opportunity to measure the rings' thickness and search for undiscovered moons. In this image of Saturn, produced on May 22, 1995 by NASA's Hubble Space Telescope, two of Saturn's known moons are visible as star like objects to the left of the planet.  For more information about the ring plane crossing see the Saturn Ring Plane Crossing web page .
Jupiter's Rings (1995-08-02)

August 2, 1995    Jupiter's Rings  Credit: NASA, Voyager Project  Explanation:  Astronomers using NASA's Voyager spacecraft to search for a ring system around Jupiter discovered these faint rings in 1979. Unlike Saturn's bright rings which are composed of chunks of rock and ice, Jupiter's rings appear to consist of fine particles of dust. One possibility is that the dust is produced by impacts with Jupiter's inner moons. This false color image has been computer enhanced. The gas giant planets, Jupiter, Saturn, Uranus, and Neptune are all known to have rings. For more information about planetary ring systems see the Planetary Rings Node.
Io: A Volcanic Moon (1995-08-03)

August 3, 1995    Io: A Volcanic Moon  Credit: NASA, Voyager Project  Explanation:  In 1610, Galileo turned his telescope to the heavens and discovered that the planet Jupiter had four bright moons. The innermost of these Galilean moons, Io, turned out to be one of the most exotic objects in the solar system. About the size of the earth's moon, Io is covered with volcanoes, many of which are currently active. The material expelled in the volcanic eruptions may contain compounds of Sulfur which take on a variety of colors and could account for its mottled, "pizza-like" appearance. For a report of a recent eruption of an Io volcano, see the NASA Infrared Telescope Facility press release and photo .
Closeup of an Io Volcano (1995-08-04)

August 4, 1995    Closeup of an Io Volcano  Credit: NASA, Voyager Project, Copyright Calvin J. Hamilton  Explanation:  In 1979, one of NASA's Voyager spacecraft made a spectacular and unexpected discovery. Io, the innermost Galilean moon of Jupiter, was covered with volcanoes and some of them were erupting! In all, Voyager 1 observed nine volcanic eruptions during its encounter with the moon. When Voyager 2 flew past four months later it was able to confirm that at least six of them were still erupting. This Voyager image of Ra Patera, a large shield volcano, shows colorful flows up to about 200 miles long emanating from the dark central volcanic vent. For more information about volcanism on Io, see Calvin J. Hamilton's Io page
Geysers on Triton (1995-08-05)

August 5, 1995    Geysers on Triton  Credit: NASA, Voyager Project, Copyright Calvin J. Hamilton  Explanation:  In August of 1989 NASA's Voyager 2 spacecraft passed by Neptune, the most distant of the solar system's gas giant planets. Its encounter with Neptune climaxed with its closest approach to Neptune's largest moon Triton. From a distance of about 24,000 miles the robot space probe surveyed Triton's surface, whose temperature averages nearly -400 degrees Fahrenheit, and discovered surprising evidence of a complex and active world. For example, the prominent dark streaks in this image seem to come from small volcanoes and may consist of nitrogen frost mixed with organic compounds ejected during geyser-like eruptions.  For more information about Triton, see Calvin J. Hamilton's Triton page .
Liftoff of Space Shuttle Columbia (1995-08-06)

August 6, 1995    Liftoff of Space Shuttle Columbia  Credit: NASA, Kennedy Space Center   Explanation:  On April 12, 1981, space flight entered a new era with the  first launch of  Space Shuttle Columbia, shown above. NASA's Space Shuttles land like a normal plane, carry a heavy cargo, carry a large crew,  make use of cheap solid fuel, and are reusable. Previous to this flight, no manned orbiting space ship had ever landed on a runway. Space Shuttles now are the flagships and the workhorses of  NASA's space going rockets.   For more information about NASA's Space Shuttle missions, see the  NASA Space Shuttle Launches page.
Night Launch of Endeavour (1995-08-07)

August 7, 1995    Night Launch of Endeavour  Credit: NASA, Kennedy Space Center Explanation:  Space Shuttle Endeavour thunders off into orbit in a rare night launch. This March 1995  mission is most famous for operating the set of astronomical telescopes known as  Astro-2. Astro-2's telescopes observed the universe in ultraviolet light - light so blue humans by themselves can't see it. Astro-2 measured the amount of ultraviolet light emitted by several interesting stars, galaxies, planets, and QSOs. Analysis of data from this NASA mission has yielded the first clear detection of helium created during the beginning of the universe.   For more information about NASA's Space Shuttle missions, see the  NASA Space Shuttle Launches page.
Columbia Waits, Discovery Launches (1995-08-08)

August 8, 1995    Columbia Waits, Discovery Launches  Credit: NASA, Kennedy Space Center Explanation:  Space Shuttle Discovery launches while the Space Shuttle Columbia is readied for a future mission. Space shuttles are launched from the Kennedy Space Center in Florida. At this date there are four operating space shuttles: Atlantis,  Columbia,  Discovery, and  Endeavour. This  mission is most famous for carrying the  Hubble Space Telescope into orbit. The Hubble Space Telescope is the largest public optical telescope ever to operate in orbit, and because it is above Earth's atmosphere it's photographs are more clear than any ground based telescope. Hubble continues to make fundamental discoveries about planets, stars, galaxies, comets, QSOs, and the universe we live in.