juliensimon/nasa-apod huggingface dataset:
Meteors Over Quebec (2010-08-16)

Meteors streaked through the sky above many of Earth's cities last week, but nobody was hurt, and no damage has been reported. The assault from space appeared to originate from someplace in the constellation of Perseus, and included millions of small projectiles hurtling toward Earth at over 200,000 kilometers per hour.  Pictured above, people gathered at ASTROLab du Mont-Megantic in southern Quebec, Canada gazed helplessly toward the sky during a similar event last year as they themselves were unable to stop the meteor onslaughts. Fortunately, Earth's defense, consisting of a planet-wide blanket of air over 100-kilometers thick, obliterated the attacking projectiles by using friction generated by their own speed to heat them into disintegration. The large triangle in the foreground, although impressive in appearance, was not part of the Earth's meteor defense system. The space attack was expected as part of the annual Perseids meteor shower as the Earth passed through sand-sized debris left over from the sun-orbiting Comet Swift-Tuttle.

Image credit: R�mi Boucher
NGC 4755: A Jewel Box of Stars (2010-08-17)

The great variety of star colors in this open cluster underlies its name: The Jewel Box.  One of the bright central stars is a red supergiant, in contrast to the many blue stars that surround it.  The cluster, also known as Kappa Crucis contains just over 100 stars, and is about 10 million years old.  Open clusters are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters.  This Jewel Box lies about 6,400 light-years away, so the light that we see today was emitted from the cluster before even the Great Pyramids in Egypt were built.  The Jewel Box, pictured above, spans about 20 light-years, and can be seen with binoculars towards the southern constellation of the cross (Crux).

Image credit: Dieter Willasch
(Astro-Cabinet)
Crescent Moon and Planets Over Portugal (2010-08-18)

Sometimes, it's fun to share the sky. Although it might appear that the two sky enthusiasts on the ridge are sharing only  a crescent moon between them, three bright planets also stand before them. The brightest point in the sky is the planet Venus, while reddish Mars floats above it, and Saturn shines off to its right. In the foreground are picturesque clumps of sand of the beach at Costa da Caparica, before the reflecting waters of the Atlantic Ocean. The evening picked to planet gaze was a particularly good one as the  Perseids meteor shower was also reaching its peak. Fortunately, this evening sky was not unique to Almada, Portugal last Thursday, but visible to sky enthusiasts the world over last week. These planets will all remain visible at sunset this week, although Venus will sink to the horizon as it closes in on the setting Sun.

Image credit: Miguel Claro
Pelican Nebula Close-up (2010-08-19)

The prominent ridge of emission featured in this vivid skyscape is designated IC 5067. Part of a larger emission nebula with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years and follows the curve of the cosmic pelican's head and neck. Fantastic, dark shapes inhabiting the view are clouds of cool gas and dust sculpted by energetic radiation from hot, massive stars. But stars are also forming within the dark shapes. In fact, twin jets emerging from the tip of the central, dark tendril are the telltale signs of an embedded protostar cataloged as Herbig-Haro 555. The Pelican Nebula itself, also known as IC 5070, is about 2,000 light-years away. To find it, look northeast of bright star Deneb in the high flying constellation Cygnus.

Image credit: Tony Hallas
NGC 1365: Majestic Island Universe (2010-08-20)

Barred spiral galaxy NGC 1365 is truly a majestic island universe some 200,000 light-years across. Located a mere 60 million light-years away toward the chemical constellation Fornax, NGC 1365 is a dominant member of the well-studied Fornax galaxy cluster. This impressively sharp color image shows intense star forming regions at the ends of the bar and along the spiral arms, and details of dust lanes cutting across the galaxy's bright core. At the core lies a supermassive black hole. Astronomers think NGC 1365's prominent bar plays a crucial role in the galaxy's evolution, drawing gas and dust into a star-forming maelstrom and ultimately feeding material into the central black hole.

Image credit: Martin Pugh
Perseid Storm (2010-08-21)

Storms on the distant horizon and comet dust raining through the heavens above are combined in this alluring nightscape. The scene was recorded in the early hours of August 13 from the Keota Star Party site on the Pawnee National Grasslands of northeastern Colorado, USA. Looking east across the prairie, the composite of 8 consecutive exposures each 30 seconds long captures the flash of lightning and a bright Perseid meteor. On the right, even the clouds can't block the light from brilliant planet Jupiter, whose mythological namesake knew how to handle both lightning bolts and meteors. Of course, this meteor's streak points back toward the shower's radiant in the heroic constellation Perseus, sharing a starry background that includes the Pleiades star cluster poised above the storm clouds. Just above the bright meteor lies the faint Andromeda Galaxy.

Image credit: Robert Arn
Hoag's Object: A Strange Ring Galaxy (2010-08-22)

Is this one galaxy or two?  This question came to light in 1950 when astronomer Art Hoag chanced upon this unusual extragalactic object.  On the outside is a ring dominated by bright blue stars, while near the center lies a ball of much redder stars that are likely much older.  Between the two is a gap that appears almost completely dark.  How Hoag's Object formed remains unknown, although similar objects have now been identified and collectively labeled as a form of ring galaxy.  Genesis hypotheses include a galaxy collision billions of years ago and the gravitational effect of a central bar that has since vanished.  The above photo taken by the Hubble Space Telescope in July 2001 reveals unprecedented details of Hoag's Object and may yield a better understanding.   Hoag's Object spans about 100,000 light years and lies about 600 million light years away toward the constellation of the Snake (Serpens).  Coincidentally, visible in the gap (at about one o'clock) is yet another ring galaxy that likely lies far in the distance.
A Milky Way Shadow at Loch Ard Gorge (2010-08-23)

Have you ever seen the Milky Way's glow create shadows? To do so, conditions need to be just right. First and foremost, the sky must be relatively clear of clouds so that the long band of the Milky Way's central disk can be seen. The surroundings must be very near to completely dark, with no bright artificial lights visible anywhere.  Next, the Moon cannot be anywhere above the horizon, or its glow will dominate the landscape. Last, the shadows can best be caught on long camera exposures.  In the above image taken in Port Campbell National Park, Victoria, Australia, seven 15-second images of the ground and de-rotated sky were digitally added to bring up the needed light and detail.  In the foreground lies Loch Ard Gorge, named after a ship that tragically ran aground in 1878. The two rocks pictured are the remnants of a collapsed arch and are named Tom and Eva after the only two people who survived that Loch Ard ship wreck. A close inspection of the water just before the rocks will show reflections and shadows in light thrown by our Milky Way galaxy. Low clouds are visible moving through the serene scene in this movie.

Image credit: Alex Cherney
(Terrastro)
Galaxy Cluster Abell 1689 Magnifies the Dark Universe (2010-08-24)

What's the matter with this cluster of galaxies? To find out what forms matter takes in the Abell 1689 cluster requires not only deep images from telescopes like the Hubble Space Telescope, but detailed computer modeling as well. To start, almost every fuzzy yellow patch in the above image is an entire galaxy. A close inspection, however, shows that many background galaxies are strangely magnified and distorted into long curving arcs by the gravitational lens deflections of the cluster.  Computer analyses of the placement and smoothness of these arcs indicate that in addition to the matter in the galaxies you can see, the cluster must also contain a significant amount of dark matter such as the model digitally superposed in purple.  Now Abell 1689 remains enigmatic because the arcs are so numerous and diverse that no single dark matter model has emerged that can explain them all and still remain consistent with dark matter models needed to constrain their motion.  Still, the detailed information available from clusters of galaxies like Abell 1689 gives hope that one day full solutions will be found that will not only fully reveal the dark matter in clusters, but also reveal the amounts of dark energy in the universe needed to lie along the line of sight to the distant arcs.   Students and Teachers: Free video online Astro 101 course
HD 10180: Richest Yet Planetary System Discovered (2010-08-25)

Do other rich planetary systems exist? Our Solar System has the most planets of any known star, most probably because it is so hard to detect planets around other stars. Sensitive measurements, though, have now uncovered a slight but complex wobble of the Sun-like star HD 10180 indicating that it has at least five planets and possibly more, making it the richest extra-solar planetary system yet known. HD 10180's planets were discovered in years of data using the sensitive HARPS spectrograph attached to the ESO's 3.6-meter telescope in La Silla, Chile. The planetary system appears quite different than our Solar System, since all of HD 10180's discovered planets have Neptune-like masses but orbit inside the distance of Mars. An artist's depiction of flying into this system is shown in the above video. In the future, more sensitive data taken over longer time periods may extend the star-wobble detection technique into the realm of uncovering more distant and more Earth-like planets.
M27: Not a Comet (2010-08-26)

While hunting for comets in the skies above 18th century France, astronomer Charles Messier diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his now famous not-a-comet list. In fact, 21st century astronomers would identify it as a planetary nebula, but it's not a planet either, even though it may appear round and planet-like in a small telescope. Messier 27 (M27) is an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible ultraviolet light. Known by the popular name of the Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the constellation Vulpecula. This impressive color composite highlights details within the well-studied central region and fainter, seldom imaged features in the nebula's outer halo. It includes narrowband images recorded using filters sensitive to emission from oxygen atoms, shown in blue-green hues, and hydrogen atoms in red.

Image credit: Matthew T. Russell
Brighter Than Mars (2010-08-27)

ven though you may have just read an email claiming Mars will be incredibly bright tonight, the brightest star on the horizon is not Mars. From central Iran on August 24th, the brightest star in this twilight desert skyview is Venus, aka the Evening Star. But a bright Mars is in the picture, just above and right of more brilliant Venus. Despite claims in the internet's annually returning Mars Hoax that Mars will be as big and bright as the Full Moon, this celestial scenario is very similar to the western sky you can see tonight. Along with Mars, the still beautiful vista includes Spica, alpha star of the constellation Virgo, above and left of Venus. Farther right of Venus, Saturn peeks through the sunset's fading glow just above the clouds. Near the opposite horizon, the Full Moon illuminating the desert is about 400,000 times brighter than Mars.

Image credit: Babak Tafreshi
Hole in the Sun (2010-08-28)

This ominous, dark shape sprawling across the face of the Sun is a coronal hole -- a low density region extending above the surface where the solar magnetic field opens freely into interplanetary space. Studied extensively from space since the 1960s in ultraviolet and x-ray light, coronal holes are known to be the source of the high-speed solar wind, atoms and electrons which flow outward along the open magnetic field lines. During periods of low activity, coronal holes typically cover regions just above the Sun's poles. But this extensive coronal hole dominated the Sun's northern hemisphere earlier this week, captured here in extreme ultraviolet light by cameras onboard the Solar Dynamics Observatory. The solar wind streaming from this coronal hole triggered auroral displays on planet Earth.
The Local Fluff (2010-08-29)

The stars are not alone.  In the disk of our Milky Way Galaxy about 10 percent of visible matter is in the form of gas, called the interstellar medium (ISM).  The ISM is not uniform, and shows patchiness even near our Sun.  It can be quite difficult to detect the local ISM because it is so tenuous and emits so little light.  This mostly hydrogen gas, however, absorbs some very specific colors that can be detected in the light of the nearest stars.  A working map of the local ISM within 10 light-years based on recent observations is shown above.  These observations show that our Sun is moving through a Local Interstellar Cloud as this cloud flows outwards from the Scorpius-Centaurus Association star forming region.  Our Sun may exit the Local Interstellar Cloud, also called the Local Fluff, during the next 10,000 years.  Much remains unknown about the local ISM, including details of its distribution, its origin, and how it affects the Sun and the Earth.

Image credit: Linda Huff
(American Scientist),
Priscilla Frisch
(U. Chicago)
Comanche Outcrop on Mars Indicates Hospitable Past (2010-08-30)

Could life once have survived on Mars? Today, neither animal nor plant life from Earth could survive for very long on Mars because at least one key ingredient -- liquid water -- is essentially absent on the red planet's rusty surface. Although evidence from the martian rovers indicates that long ago Mars might once have had liquid water on its surface, that water might also have been too acidic for familiar life forms to thrive.  Recently, however, a newly detailed analysis of an unusual outcropping of rock and soil chanced upon in 2005 by the robotic Spirit rover has uncovered a clue indicating that not all of Mars was always so acidic. The mound in question, dubbed Comanche Outcrop and visible near the top of the above image, appears to contain unusually high concentrations of elements such as magnesium iron carbonate. The above image is shown in colors exaggerated to highlight the differences in composition. Since these carbonates dissolve in acid, the persistence of these mounds indicates that water perhaps less acidic and more favorable for life might have once flowed across Mars. More detailed analyses and searches for other signs will surely continue.
The Annotated Galactic Center (2010-08-31)

The sky toward the center of our Galaxy is filled with a wide variety of celestial wonders, many of which are visible from a dark location with common binoculars. Constellations near the Galactic Center include Sagittarius, Libra, Scorpius, Scutum, and Ophiuchus. Nebulas include Messier objects M8, M16, M20, as well as the Pipe and Cat's Paw nebulas. Visible open star clusters include M6, M7, M21, M23, M24, and M25, while globular star cluster M22 is also visible. A hole in the dust toward the Galactic Center reveals a bright region filled with distant stars known as Baade's Window, which is visible between M7 and M8.  Moving your cursor over the above image the will bring up an un-annotated version.

Image credit: Jaime Fernandez
Earth and Moon from MESSENGER (2010-09-01)

What does Earth look like from the planet Mercury? The robotic spacecraft MESSENGER found out as it looked toward the Earth during its closest approach to the Sun about three months ago.  The Earth and Moon are visible as the double spot on the lower left of the above image.  Now MESSENGER was not at Mercury when it took the above image, but at a location from which the view would be similar.  From Mercury, both the Earth and its comparatively large moon will always appear as small circles of reflected sunlight and will never show a crescent phase.  MESSENGER has zipped right by Mercury three times since being launched in 2004, and is scheduled to enter orbit around the innermost planet in March of 2011.
The Bubble Nebula (2010-09-02)

Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape. Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Above and right of the Bubble's center is a hot, O-type star, several hundred thousand times more luminous and approximately 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula lies a mere 11,000 light-years away toward the boastful constellation Cassiopeia. A false-color Hubble palette was used to create this sharp image and shows emission from sulfur, hydrogen, and oxygen atoms in red, green, and blue hues.  The image data was recorded using a small telescope under clear, steady skies, from Mount Wilson Observatory.

Image credit: Dave Jurasevich
The Small Cloud of Magellan (2010-09-03)

Portuguese navigator Ferdinand Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two celestial wonders easily visible for southern hemisphere skygazers are known as the Clouds of Magellan. These cosmic clouds are now understood to be dwarf irregular galaxies, satellites of our larger spiral Milky Way Galaxy. The Small Magellanic Cloud actually spans 15,000 light-years or so and contains several hundred million stars. About 210,000 light-years away in the constellation Tucana, it is more distant than other known Milky Way satellite galaxies, including the Canis Major and Sagittarius Dwarf galaxies and the Large Magellanic Cloud. This sharp image also includes two foreground globular star clusters NGC 362 (bottom right) and 47 Tucanae. Spectacular 47 Tucanae is a mere 13,000 light-years away and seen here to the left of the Small Magellanic Cloud.  Take a short survey about viewing astronomy images on mobile devices.

Image credit: Bogdan Jarzyna
Young Suns of NGC 7129 (2010-09-04)

Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only a few million years old, it is likely that our own Sun formed in a similar stellar nursery some five billion years ago. Most noticeable in the sharp, (zoomable) image are the lovely bluish dust clouds that reflect the youthful starlight, but the smaller, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color is characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. At the estimated distance of NGC 7129, this telescopic view spans about 40 light-years.  Take a short survey about viewing astronomy images on mobile devices.

Image credit: Ken Crawford
GRO J1655-40: Evidence for a Spinning Black Hole (2010-09-05)

In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole.  Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.  The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second.  Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly.  What physical mechanisms actually cause the flickering -- and a slower quasi-periodic oscillation (QPO) -- in accretion disks surrounding black holes and neutron stars remains a topic of much research.
A Laser Strike at the Galactic Center (2010-09-06)

Why are these people shooting a powerful laser into the center of our Galaxy?  Fortunately, this is not meant to be the first step in a Galactic war.  Rather, astronomers at the Very Large Telescope (VLT) site in Chile are trying to measure the distortions of Earth's ever changing atmosphere.  Constant imaging of high-altitude atoms excited by the laser -- which appear like an artificial star -- allow astronomers to instantly measure atmospheric blurring.  This information is fed back to a VLT telescope mirror which is then slightly deformed to minimize this blurring.  In this case, a VLT was observing our Galaxy's center, and so Earth's atmospheric blurring in that direction was needed.  As for inter-galaxy warfare, when viewed from our Galaxy's center, no casualties are expected.  In fact, the light from this powerful laser would combine with light from our Sun to together appear only as bright as a faint and distant star.
Space Shuttle Tribute Poster: Endeavour (2010-09-07)

They are some of the most complex machines ever built. From a standing start they can launch a school- bus sized object up so high and moving so fast that it won't fall back down. They have launched numerous revolutionary satellites that enable humans to communicate across the globe, to better understand Earth's atmosphere, and to peer into the distance universe. They are NASA's Space Shuttles, and NASA has recently released large digital posters to honor them. While the inaugural flight was in 1981, the shuttle fleet is aging and is now nearing retirement. Pictured above, the space shuttle Endeavour is shown rising to orbit, with patches for each of its missions shown in a spiral. Endeavour was named for the HMS Endeavour, a British research ship that explored the south Pacific Ocean in the 1700s, depicted on the lower right. On the upper left are panoramic windows delivered by Endeavour to the International Space Station earlier this year. In the background near the top is the NGC 602 nebula as imaged by the Hubble Space Telescope, which was serviced by Endeavour in 1993.  Posters for all of the shuttles, including Atlantis, Challenger, Columbia, Discovery, Endeavour are available.
NGC 4911: Spiral Diving into a Dense Cluster (2010-09-08)

Why are there faint rings around this spiral galaxy? Possibly because the galaxy, NGC 4911, is being pulled at by its neighbors as it falls into the enormous Coma Cluster of Galaxies. If NGC 4911 ends up like most of the galaxies in the central Coma cluster, it will become a yellowish elliptical galaxy, losing not only its outer layers, but dust, gas, and its cadre of surrounding satellite galaxies as well. Currently, however,  this process is just beginning. Visible in the above deep image from the Hubble Space Telescope are NGC 4911's bright nucleus, distorted spiral arms laced with dark dust, clusters of recently formed stars, unusual faint outer rings, dwarf companion galaxies, and even faint globular clusters of stars. Far in the distance many unassociated galaxies from the early universe are visible, some even through NGC 4911 itself. The Coma Cluster contains over 1,000 galaxies making it among the most massive objects known. NGC 4911 can be found to the lower left of the great cluster's center.