omnianasa/nasa-apod-metadata huggingface dataset:
Leonids from Leo (2002-11-17)
Is Leo leaking? Leo, the famous sky constellation visible on the left of the above all-sky photograph, appears to be the source of all the meteors seen in last year's Leonids Meteor Shower.  That Leonids point back to Leo is not a surprise - it is the reason that this November meteor shower is called the Leonids.  Sand-sized debris expelled from Comet Tempel-Tuttle follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the constellation Leo.  Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Leo.  Over 100 bright meteors can be seen in the above half-hour exposure.  The intensity of the Leonid Meteor Shower in 2002 is uncertain but may approach one per second for some locations on November 18 and 19.
The Car, the Hole, and the Peekskill Meteorite (2002-11-18)
Tomorrow's picture: 2002 Leonids  < | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >  Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Technical Rep.: Jay Norris. Specific rights apply. A service of: LHEA at NASA / GSFC & NASA SEU Edu. Forum & Michigan Tech. U.
A Kitt Peak Leonid at 1026 UT (2002-11-19)
Reports of the 2002 Leonid Meteor Shower are coming in from across the world.  Preliminary indications have the shower as less active than last year but with an impressive peak seen through 1030 and 1100 Universal Time visible from much of North America.  Observers reported many meteors at the peak arriving in groups.  Pictured above is one such meteor from the peak caught earlier today by the Night Sky Live continuous camera at Kitt Peak National Observatory in Arizona, USA.  A memorable event of the 2002 Leonids was when the town of Mitzpe Ramon in Israel dimmed its lights to allow better imaging of Leonid meteors from Wise Observatory.
Leonids vs. The Moon (2002-11-20)
Beautiful and bright, the 2002 Leonid meteors battled against glaring moonlight. This winning example, from Tuesday morning skies above Laughlin, Nevada, USA, finds an undaunted Leonid streaking between the familiar constellation of Orion (left) and an overexposed full Moon. As anticipated, the Leonid shower packed a double punch on November 19 with planet Earth plunging through two dense clouds of meteroids, dusty debris left by the passage of comet Tempel-Tuttle. Some European observers reported 10 or so meteors a minute during the first peak near 4:00 Universal Time while North American skygazers witnessed slightly lower rates near the second peak around 10:30 UT. Overall, observed rates were much lower than last year's Leonid meteor storm, but for many the sky was still filled with a rewarding spectacle of bright meteors. And that performance may be a fond farewell for years to come. The annual Leonid meteor shower will not likely approach even these rates again until the end of this century.
Starburst Galaxy M94 (2002-11-21)
What could cause the center of M94 to be so bright?  Spiral galaxy M94 has a ring of newly formed stars surrounding its nucleus, giving it not only an unusual appearance but also a strong interior glow.  A leading progenitor hypothesis holds that an elongated knot of stars known as a bar rotates in M94 and has generated a burst of star formation in the form of an outward moving ring.  M94, pictured above digitally sharpened, spans about 30,000 light years, lies about 15 million light years away, and can be seen with a small telescope toward the constellation of Canes Venatici.
Full Moon, Lake, and Leonids Indeed (2002-11-22)
Full of itself moon - EVERYONE SHOULD LOOK AT ME. What's 33 years?  And for those who need a story ... photographer Blake Suddeth took over a hundred digital pictures early Tuesday morning in order to capture this single, gorgeous 10 second exposure of a "Leonid of the Lake" meteor flashing by a very full of itself moon. The dreamlike foreground lake and fog are courtesy of Greenwood, South Carolina, USA.
Mare Orientale (2002-11-23)
Like a target ring bull's-eye, the Mare Orientale is one of the most striking large scale lunar features. Located on the Moon's extreme western edge, this impact basin is unfortunately difficult to see from an earthbound perspective. It is over 3 billion years old, about 600 miles across and was formed by the impact of an asteroid sized object. The collision caused ripples in the lunar crust resulting in the three concentric circular features visible in this 1967 photograph made by NASA's Lunar Orbiter 4. Molten lava from the Moon's interior flooded the impact site through the fractured crust creating a mare. Dark, smooth regions on the moon are called mare (Latin for sea), because early astronomers thought these areas might be oceans.
Hubble Floats Free (2002-11-24)
Why put observatories in space?  Most telescopes are on the ground.  On the ground, you can deploy a heavier telescope and fix it more easily.  The trouble is that Earth-bound telescopes must look through the Earth's atmosphere. First, the Earth's atmosphere blocks out a broad range of the electromagnetic spectrum, allowing a narrow band of visible light to reach the surface. Telescopes which explore the Universe using light beyond the visible spectrum, such as those onboard the Chandra X-ray Observatory need to be carried above the absorbing atmosphere. Second, the Earth's atmosphere blurs the light it lets through.  The blurring is caused by varying density and continual motion of air.  By orbiting above the Earth's atmosphere, the Hubble Space Telescope, pictured above, can get clearer images. In fact, even though HST has a mirror 15 times smaller than large Earth-bound telescopes, it can still resolve finer details. A future large optical telescope in space is planned.
The Earth's Magnetic Field (2002-11-25)
Why does the Earth have a magnetic field?  The electrical conductivity of the molten plasma of the Earth's core should be able to damp the current magnetic field in only thousands of years.  Yet our five billion year old Earth clearly causes magnets to point to (defined) north.  The mystery is still being studied but recently thought related to motions in the Earth's liquid outer core.  Specifically, as portions of the outer core cool and fall inward, oceans of the liquid iron-rich magma rise outward, forced into a helical motion by the spin of the Earth.  This motion, many geologists now believe, regenerates Earth's magnetism.  Pictured above, a computer simulation shows the resulting magnetic field lines out to two Earth radii, with blue lines directed inward and yellow lines directed outward.
Name This Martian Robot (2002-11-26)
NASA will launch two robots to Mars next year and you can help name them. The Mars Exploration Rovers are scheduled for launch on or near this coming June, when Mars and Earth are relatively close in their orbits.  The landing craft are expected to touch down on Mars in January 2004 and deploy the robot rovers shortly thereafter.  Rovers have the capability to crawl about 100 meters each day of their planned 90-day mission.  The mission's scientific purpose is to seek out and  inspect interesting rocks and terrain that could give clues to the past of Mars. Suggestions for names should be sent here, accompanied by a short essay, by 2003 January 31.  (Eds. Note: The contest is only open to school children in grades K-12.)
Leonids and Leica (2002-11-27)
Tomorrow's picture: when galaxies collide  < | Archive | Index | Search | Calendar | Glossary | Education | About APOD | >  Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Technical Rep.: Jay Norris. Specific rights apply. A service of: LHEA at NASA / GSFC & NASA SEU Edu. Forum & Michigan Tech. U.
The Supermassive Black Holes of NGC 6240 (2002-11-28)
The Hubble optical image on the left shows NGC 6240 in the throes of a titanic galaxy - galaxy collision 400 million light-years away. As the cosmic catastrophe plays out, the merging galaxies spew forth distorted tidal tails of stars, gas, and dust and undergo frantic bursts of star formation. Using the orbiting Chandra Observatory's x-ray vision to peer within the bright central regions of NGC 6240 astronomers believe they have uncovered, for the first time, not one but two enormous orbiting black holes, by detecting the characteristic x-ray radiation from the interstellar debris swirling toward them. In the false-color close-up view at right, the x-ray data clearly show the black hole sources (shaded blue) separated by about 3,000 light-years. Einstein's theory of gravity predicts that such a pair of black holes must spiral closer together, and ultimately coalesce into a single, even more massive black hole after several hundred million years. In the final moments the merging supermassive black holes will produce an extremely powerful burst of gravitational radiation.
Open Star Clusters M35 and NGC 2158 (2002-11-29)
Open clusters of stars can be near or far, young or old, and diffuse or compact.  Open clusters may contain from 100 to 10,000 stars, all of which formed at nearly the same time.  Bright blue stars frequently distinguish younger open clusters.  M35, pictured above on the upper left, is a relatively nearby at 2800 light years distant, relatively young at 150 million years old, and relatively diffuse, with about 2500 stars spread out over a volume 30 light years across.  An older and more compact open cluster, NGC 2158, is visible above on the lower right.  NGC 2158 is four times more distant that M35, over 10 times older, and much more compact as it contains many more stars in roughly the same volume of space.  NGC 2158's bright blue stars have self-destructed, leaving cluster light to be dominated by older and yellower stars.  Both clusters are visible toward the constellation of Gemini -- M35 with binoculars and NGC 2158 with a small telescope.
Surveyor Hops (2002-11-30)
This panorama of the cratered lunar surface was constructed from images returned by the US Surveyor 6 lander. Surveyor 6 was not the first spacecraft to accomplish a soft landing on the Moon ... but it was the first to land and then lift off again! After the spacecraft touched down near the center of the Moon's nearside in November of 1967, NASA controllers commanded it to hop. Briefly firing its rocket engine and lifting itself some 4 meters above the surface, the Surveyor moved about 2.5 meters to one side before setting down again. The hopping success of Surveyor 6 essentially marked the completion of the Surveyor series main mission - to determine if the lunar terrain was safe for the planned Apollo landings.
The Pleiades Star Cluster (2002-12-01)
It is the most famous star cluster on the sky. The Pleiades can be seen without binoculars from even the depths of a light-polluted city.  Also known as the Seven Sisters and M45, the Pleiades is one of the brightest and closest open clusters.   The Pleiades contains over 3000 stars, is about 400 light years away, and only 13 light years across.  Quite evident in the above photograph are the blue reflection nebulae that surround the bright cluster stars.  Low mass, faint, brown dwarfs have recently been found in the Pleiades.
Nearby Spiral M33 (2002-12-02)
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 be visible with a good pair of binoculars. The above high-resolution image from the 0.90-m telescope at Kitt Peak National Observatory is a four-color composite.
Eclipse Over Acacia (2002-12-03)
On December 4th, for the second time in as many years, the Moon's shadow will track across southern Africa bringing a total solar eclipse to African skies. Reaching Africa just before 6:00 Universal Time, the narrow path of totality - corresponding to the path of the Moon's umbra or dark central shadow - will run eastward through Angola, Namibia (Caprivi Strip), Botswana, Zimbabwe, South Africa's Kruger National Park, and Mozambique. Moving out across the Indian Ocean it will ultimately cross onto the Australian continent at sunset (around 9:10 UT). Observers directly in this path could catch at most a minute or so of the eclipse at its total phase, but at least a partial eclipse will be visible over much of Africa, Australia, some parts of Indonesia, and eastern Antarctica. While watching last year's June 21 eclipse, astronomer Fred Espenak recorded a series of exposures used to construct this dramatic composite image. The sequence follows the 2001 geocentric celestial event from start to finish above a thorny acacia tree near Chisamba, Zambia.
Moon, Mars, Venus, and Spica (2002-12-04)
Gliding toward today's total eclipse of the Sun, the crescent Moon has been rising early, just before dawn. And as a prelude to its close solar alignment, the Moon also completed a lovely celestial triangle, closing with bright planets Mars and Venus on the morning of December 1. While the total solar eclipse can only be seen from a narrow corridor, skygazers around the globe could appreciate this lunar-planetary conjunction. This view is from near Nashville Tennessee, USA, and finds brilliant Venus at the lowest corner of the triangle with a much fainter Mars immediately to the right of the Moon. The Moon's sunlit crescent is overexposed, but details of the lunar night side are revealed by earthshine. Above and to the right of the trio is Spica, brightest star in the constellation Virgo.
NGC 2359: Thor's Helmet (2002-12-05)
NGC 2359 is a striking emission nebula with an impressive popular name - Thor's Helmet. Sure, its suggestive winged appearance might lead some to refer to it as the "duck nebula", but if you were a nebula which name would you choose? By any name NGC 2359 is a bubble-like nebula some 30 light-years across, blown by energetic winds from an extremely hot star seen near the center and classified as a Wolf-Rayet star. Wolf-Rayet stars are rare massive blue giants which develop stellar winds with speeds of millions of kilometers per hour. Interactions with a nearby large molecular cloud are thought to have contributed to this nebula's more complex shape and curved bow-shock structures. NGC 2359 is about 15,000 light-years distant toward the constellation Canis Major.
Zimbabwe Solar Eclipse (2002-12-06)
Normally hiding from view in the glare of the Sun, the shy solar corona came out to play Wednesday as a total solar eclipse graced morning skies over southern Africa. This telescopic image of the Sun's corona or outer atmosphere shimmering around the silhouetted Moon was recorded near the centreline of the total eclipse path, 10 kilometers north of Beitbridge, Zimbabwe. At that location, near the Zimbabwe - South Africa border, the total phase pictured here lasted a leisurely one minute and 23 seconds. Zimbabwean photographer Murray Alexander reported that fortunately no clouds interfered but few people were present, while many watching from the South Africa side were clouded out. Still, if you missed this geocentric celestial event, just wait until next year. Two solar eclipses and two lunar eclipses are on planet Earth's schedule for 2003, along with a transit of Mercury.
Jupiter, Io and Shadow (2002-12-07)
Pictured above is the innermost of Jupiter's Galilean satellites, Io, superposed in front of the gas giant planet. To the left of Io is a dark spot that is Io's own shadow.  A solar eclipse would be seen from within the shadow spot on Jupiter. Viewed from planet Earth, similar shadows of Jupiter's large moons can often be seen crossing the giant planet's disk. But during the next several months, the Galilean moons can also be seen crossing in front of each other as, for a while, their orbits lie nearly edge-on when viewed by earthbound observers. This true-color contrast-enhanced image was taken two years ago by the robot spacecraft Cassini, as it passed Jupiter on its way to Saturn in 2004.
The International Space Station Expands Yet Again (2002-12-08)
The developing International Space Station (ISS) has changed its appearance yet again.  Earlier this month the Space Shuttle Endeavor visited the ISS and installed the fourth of eleven pieces that will compose the Integrated Truss Structure.  The new P-1 Truss is visible on the left, below the extended solar panels.  The world's foremost space outpost can be seen developing over the past few years by comparing the above image to past images.  Also visible above are many different types of modules, a robotic arm, several wing-like solar panels, and a supply ship.  Construction began on the ISS in 1998 and the core structure should be in place before 2005.
Moon Shadow Moves Over Africa (2002-12-09)
When the Moon's shadow reached out and touched the Earth last week, the result was a solar eclipse. Such an eclipse is total only for observers located along a narrow path corresponding to the ground track of the shadow's dark central portion or umbra.  For this eclipse, racing along at nearly 2000 kilometers per hour, the Moon's umbra obligingly crossed over land along regions of Africa and Australia. Totality lasted for about two minutes or less at a given location.  Many nearby regions fell within the lighter but much wider outer shadow region, the penumbra, and witnessed a partial solar eclipse.  The above movie follows the Moon's shadow as it crossed Africa during a similar eclipse in June 2001. Each frame is separated in time by about 20 minutes. The movie was created from frames taken by the orbiting European satellite MeteoSat-6.
M17: Omega Nebula Star Factory (2002-12-10)
In the depths of the dark clouds of dust and molecular gas known as M17, stars continue to form.  The similarity to the Greek letter capital Omega gives the molecular cloud its popular name, but the nebula is also known as the Swan Nebula, the Horseshoe Nebula, and M17.  The darkness of these molecular clouds results from background starlight being absorbed by thick carbon-based smoke-sized dust.  As bright massive stars form, they produce intense and energetic light that slowly boils away the dark shroud.  M17, pictured above, is visible with binoculars towards the constellation of Sagittarius, lies 5000 light-years away, and spans 20 light-years across.
Meteors Between Stars and Clouds (2002-12-11)
Streaking high above diffuse clouds -- but well in front of distant stars -- are sand-sized bits of an ancient comet: meteors.  These bits flaked off Comet Tempel-Tuttle during its pass through the inner Solar System about 150 years ago.  Far in the background are stars toward the constellation of Ursa Major. The above image is digital combination of 12 exposures taken on the morning of November 19 from Florida, USA.  Observers there reported a strong peak in faint meteors between 5:30 and 6:00 EST, with a particularly strong minute coming at 5:46 EST when 22 Leonid meteors were counted.  The likely less impressive Geminid meteor shower will peak over the next three nights.
Apollo 17: Last on the Moon (2002-12-12)
In December of 1972, Apollo 17 astronauts Eugene Cernan and Harrison Schmitt spent about 75 hours on the Moon, in the Taurus-Littrow valley, while colleague Ronald Evans orbited overhead. Near the beginning of their third and final excursion across the lunar surface, Schmitt took this picture of Cernan flanked by an American flag and their lunar rover's umbrella-shaped high-gain antenna. The prominent Sculptured Hills lie in the background while Schmitt's reflection can just be made out in Cernan's helmet. The Apollo 17 crew returned with 110 kilograms of rock and soil samples, more than from any of the other lunar landing sites. And after thirty years, Cernan and Schmitt are still the last to walk on the Moon.
The Crown of the Sun (2002-12-13)
During a total solar eclipse, the Sun's extensive outer atmosphere or corona is an awesome and inspirational sight. Yet the subtle shades and shimmering features of the corona that engage the eye span a brightness range of over 10,000 to 1, making them notoriously difficult to capture in a photograph. Still, this single five second exposure comes very close to revealing the crown of the Sun in all its glory. The color picture was taken with a specially built coronal camera and telescope during the December 4th total eclipse from Messina, South Africa. The camera's design incorporates a precisely made filter whose density, or ability to block light, decreases markedly with distance from the filter center, compensating for the difference between the brighter inner portion of the corona at the Sun's edge and the much fainter outer regions. The central spot in the image corresponds to a calibration window centered on the eclipsed Sun.
IC 418: The Spirograph Nebula (2002-12-14)
What is creating the strange texture of IC 418?  Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood.  Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours.  By contrast, evidence indicates that only a few million years ago, IC 418 was probably a well-understood star similar to our Sun.  Only a few thousand years ago, IC 418 was probably a common red giant star.  Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white-dwarf star, visible in the image center.  The light from the central core excites surrounding atoms in the nebula causing them to glow.  IC 418 lies about 2000 light-years away and spans 0.3 light-years across.  This false-color image taken from the Hubble Space Telescope reveals the unusual details.
A Network of Microlensing Caustics (2002-12-15)
A virtual sky map like this would be of interest to astronomers studying gravitational microlensing. In microlensing, the gravity of stars near the line of sight can act to magnify the light of background objects such as distant stars, or quasars. Nowhere is this magnification greater than near a gravitational lensing caustic. In the above computer simulated map, caustics are discernible as the sharp bright curved lines. When a background quasar moves across a microlensing caustic, it can appear dramatically brighter. Many astronomers thought microlensing events practically immeasurable even twenty years ago, but within the past five years now hundreds have been found. Precise measurements of microlensing are now providing unique information about the composition and distribution of matter in galaxies and the universe. Some astronomers now predict that future microlensing searches might even isolate planets orbiting distant stars.
Night and Day in Melas Chasma on Mars (2002-12-16)
What types of terrain are found on Mars?  Part of the answer comes from thermal imaging by the robot spacecraft 2001 Mars Odyssey currently orbiting Mars.  The above picture is a superposition of two infrared images, a black and white image taken during Martian daylight and a false-color image taken at night.  For the daytime image, dark colors mean cool temperatures, dropping from about -5 degrees Celsius to low as -35 degrees Celsius.  Shadowed regions appear particularly dark, while grooved structure on the floor of Melas Chasma indicates successively overlapping landslides.  In the nighttime swath, blue areas have cooled relatively quickly, indicating a composition of fine-grained dust and sand.