juliensimon/nasa-apod huggingface dataset:
A Dangerous Sunrise on Gliese 876d (2012-04-29)

On planet Gliese 876d, sunrises might be dangerous. Although nobody really knows what conditions are like on this close-in planet orbiting variable red dwarf star Gliese 876, the above artistic illustration gives one impression. With an orbit well inside Mercury and a mass several times that of Earth, Gliese 876d might rotate so slowly that dramatic differences exist between night and day.  Gliese 876d is imagined above showing significant volcanism, possibly caused by gravitational tides flexing and internally heating the planet, and possibly more volatile during the day.  The rising red dwarf star shows expected stellar magnetic activity which includes dramatic and violent prominences. In the sky above, a hypothetical moon has its thin atmosphere blown away by the red dwarf's stellar wind. Gliese 876d excites the imagination partly because it is one of the few extrasolar planets known to be in or near to the habitable zone of its parent star.

Image credit: Inga Nielsen (Hamburg Obs.,
Gate to Nowhere)
Aurora Over Raufarh�fn (2012-04-30)

It was all lined up even without the colorful aurora exploding overhead. If you follow the apex line of the recently deployed monuments of Arctic Henge in Raufarh�fn in northern Iceland from this vantage point, you will see that they point due north. A good way to tell is to follow their apex line to the line connecting the end stars of the Big Dipper, Merak and Dubhe, toward Polaris, the bright star near the north spin axis of the Earth projected onto the sky.  By design, from this vantage point, this same apex line will also point directly at the midnight sun at its highest point in the sky just during the summer solstice of Earth's northern hemisphere. In other words, the Sun will not set at Arctic Henge during the summer solstice in late June, and at its highest point in the sky it will appear just above the aligned vertices of this modern monument. The above image was taken in late March during a beautiful auroral storm.

Image credit: Stephane Vetter
(Nuits sacrees)
Higgs Boson Explained by Cartoon (2012-05-01)

What is all this fuss about the Higgs boson? The physics community is abuzz that a fundamental particle expected by the largely successful Standard Model of particle physics may soon be found by the huge Large Hadron Collider (LHC) at CERN in Europe. The term boson refers to a type of fundamental particle with similarities to the photon, while Higgs refers to Peter Higgs, a physicist who among others published research predicting the mechanism through which such a particle might act. The above animated cartoon explains in humorous but impressive detail why the Higgs boson is expected, and one method that the Large Hadron Collider is using to find it. Although some rumors hint that preliminary traces of the Higgs boson are already being found, even not finding this unusual particle would open the door to a new fundamental understanding of how our universe works.

Image credit: Jorge Cham,
PHD Comics
Saturn's Moon Helene in Color (2012-05-02)

Although its colors may be subtle, Saturn's moon Helene is an enigma in any light. The moon was imaged in unprecedented detail last June as the robotic Cassini spacecraft orbiting Saturn swooped to within a single Earth diameter of the diminutive moon. Although conventional craters and hills appear, the above image also shows terrain that appears unusually smooth and streaked. Planetary astronomers are inspecting these detailed images of Helene to glean clues about the origin and evolution of the 30-km across floating iceberg. Helene is also unusual because it circles Saturn just ahead of the large moon Dione, making it one of only four known Saturnian moons to occupy a gravitational well known as a stable Lagrange point.   Dark Mysteries: Astronomy Seminar of the Week
M106 Close Up (2012-05-03)

Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial wonder was discovered in 1781 by the metric French astronomer Pierre Mechain. Later, it was added to the catalog of his friend and colleague Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe: a spiral galaxy around 30 thousand light-years across located only about 21 million light-years beyond the stars of the Milky Way. Along with prominent dust lanes and a bright central core, this colorful composite image highlights youthful blue star clusters and reddish stellar nurseries that trace the galaxy's spiral arms. The high resolution galaxy portrait is a mosaic of data from Hubble's sharp ACS camera combined with groundbased color image data. M106 (aka NGC 4258) is a nearby example of the Seyfert class of active galaxies, seen across the spectrum from radio to X-rays. Energetic active galaxies are powered by matter falling into a massive central black hole.
Fermi Epicycles: The Vela Pulsar's Path (2012-05-04)

ring the cosmos at extreme energies, the Fermi Gamma-ray Space Telescope orbits planet Earth every 95 minutes. By design, it rocks to the north and then to the south on alternate orbits in order to survey the sky with its Large Area Telescope (LAT). The spacecraft also rolls so that solar panels are kept pointed at the Sun for power, and the axis of its orbit precesses like a top, making a complete rotation once every 54 days. As a result of these multiple cycles the paths of gamma-ray sources trace out complex patterns from the spacecraft's perspective, like this mesmerising plot of the path of the Vela Pulsar. Centered on the LAT instrument's field of view, the plot spans 180 degrees and follows Vela's position from August 2008 through August 2010. The concentration near the center shows that Vela was in the sensitive region of the LAT field during much of that period. Born in the death explosion of a massive star within our Milky Way galaxy, the Vela Pulsar is a neutron star spinning 11 times a second, seen as the brightest persistent source in the gamma-ray sky.
Full Moonrise (2012-05-05)

Rising as the Sun sets, tonight's Full Moon could be hard to miss. Remarkably, its exact full phase (May 6 03:36 UT) will occur less than two minutes after it reaches perigee, the closest point to Earth in the Moon's orbit, making it the largest Full Moon of 2012. The Full Perigee Moon will appear to be some 14 percent larger and 30 percent brighter than a Full Moon near apogee, the most distant point in the elliptical lunar orbit. In comparison, though, it will appear less than 1 percent larger and almost as bright as April's Full Moon, captured in this telephoto image rising over suburban Fort Collins, Colorado, USA. For that lunation, Full Moon and perigee were about 21 hours apart. Of course, if you manage to miss May's Full Perigee Moon, make a note on your calendar. Your next chance to see a Full Moon close to perigee, will be next year on June 23.

Image credit: Robert Arn
In the Center of the Omega Nebula (2012-05-06)

In the depths of the dark clouds of dust and molecular gas known as the Omega Nebula, stars continue to form. The above image from the Hubble Space Telescope's Advanced Camera for Surveys shows exquisite detail in the famous star-forming region. The dark dust filaments that lace the center of Omega Nebula were created in the atmospheres of cool giant stars and in the debris from supernova explosions. The red and blue hues arise from glowing gas heated by the radiation of massive nearby stars. The points of light are the young stars themselves, some brighter than 100 Suns. Dark globules mark even younger systems, clouds of gas and dust just now condensing to form stars and planets. The Omega Nebula lies about 5000 light years away toward the constellation of Sagittarius. The region shown spans about 3000 times the diameter of our Solar System.   Gallery: Supermoon 2012
Supermoon Over Paris (2012-05-07)

Did you see that full Moon Saturday night? Dubbed a supermoon, the latest fully illuminated moon appeared slightly larger than usual because it occurred unusually near the closest point in its orbit to Earth. Pictured above, the supermoon was captured Saturday night rising behind the top of the Eiffel Tower in Paris, France. Of course, the angular extent of the moon in comparison to foreground objects can be adjusted just by changing the observer's distance to the foreground object. When compared to nearby objects the moon may appear tiny, but when compared to distant objects -- the moon may appear huge. Next month yet another full moon is expected, this one appearing about one percent smaller.   Browse:  Supermoon Image Gallery

Image credit: VegaStar Carpentier
The Light of Stars (2012-05-08)

What's moving? Time lapse videos of the sky can be quite spectacular when they last long enough for stars, planets, aurora, and clouds to appear to move in just a few seconds. Pictured above, however, astrovideographer Daniel L�pez not only treats us to several inspiring time lapse videos of the night sky, but shows us how he used sliders and motorized cranes to move the imaging cameras themselves, creating a thrilling three-dimensional sense of depth. The video sequences were taken from Tenerife on the Canary Islands of Spain over the past two months, and show scenes including sunset shadows approaching Observatorio del Teide, the Milky Way shifting as the sky rotates, bright planets Venus and trailing Jupiter setting, a reddened Moon rising through differing layers of atmospheric refraction, the MAGIC gamma-ray telescopes slewing to observe a new source, and unusual foreground objects including conic Echium wildpretii plants, unusual rock formations, and a spider moving about its web.  The video concludes by showing the Belt of Venus descending on Mt. Teide as the morning sun rises.   New Mirror: APOD is now available in Indonesian from Indonesia.

Image credit: Daniel L�pez
(El Cielo de Canarias);
 Music:  La Busqueda de Ianna (Epic Soul Factory)
Shuttle Enterprise Over New York (2012-05-09)

What's that in the background? Two famous New York City icons stand tall in the above photo taken last week. On the left looms the Statue of Liberty, a universal symbol of freedom, while on the right rises the Empire State Building, now the second largest building in the city. What's unique about this once-in-a-lifetime photograph, though, is the third icon that appears to Lady Liberty's left. High in the air and far in the background flies the space shuttle Enterprise -- perched atop a 747 jet --  on the way to its new home. New Yorkers and visitors to the Big Apple can visit the test space shuttle at the Intrepid Sea, Air & Space Museum on the West Side of Manhattan starting July 19.   Neptune & Vulcan Astronomy Seminar of the Week
Green Flash and Super Moon (2012-05-10)

It was really not about superheroes as on May 6 the much touted Super Moon, the largest Full Moon of 2012, rose over this otherwise peaceful harbor. And no supervillains were present either as boats gently rocked at their moorings near the checkerboard La Perdrix lighthouse on the coast of Brittany, France. But the rise of the Super Moon was preceded by a Green Flash, captured in the first frame of this timelapse video recorded that night. The cropped image of the frame, a two second long exposure, shows the strongly colored flash left of the lighted buoy near picture center. While the Super Moon was enjoyed at locations all around the world, the circumstances that produced the Green Flash were more restrictive. Green flashes for both Sun and Moon are caused by atmospheric refraction enhanced by long, low, sight lines and strong atmospheric temperature gradients often favored by a sea horizon.

Image credit: Laurent Laveder
Sun vs. Super Moon (2012-05-11)

The Super Moon wins, by just a little, when its apparent size is compared to the Sun in this ingenious composite picture. To make it, the Full Moon on May 6 was photographed with the same camera and telescope used to image the Sun (with a dense solar filter!) on the following day. Of course, on May 6 the Moon was at perigee, the closest point to Earth in its eliptical orbit, making it the largest Full Moon of 2012. Two weeks later, on May 20, the Moon will be near apogee, the most distant point in its orbit, so by then it will be nearly at its smallest apparent size. It will also be a dark New Moon on that date. And for some the New Moon will be surprisingly easy to compare to the Sun, because on May 20 the first solar eclipse of 2012 will be visible from much of Asia, the Pacific, and North America. Along a path 240 to 300 kilometers wide, the eclipse will be annular. Near apogee the smaller silhouetted Moon will fit just inside the bright solar disk.

Image credit: Charlie Szabototh
The Hydra Cluster of Galaxies (2012-05-12)

Two stars within our own Milky Way galaxy anchor the foreground of this cosmic snapshot. Beyond them lie the galaxies of the Hydra Cluster. In fact, while the spiky foreground stars are hundreds of light-years distant, the Hydra Cluster galaxies are over 100 million light-years away. Three large galaxies near the cluster center, two yellow ellipticals (NGC 3311, NGC 3309) and one prominent blue spiral (NGC 3312), are the dominant galaxies, each about 150,000 light-years in diameter. An intriguing overlapping galaxy pair cataloged as NGC 3314 is just above and left of NGC 3312. Also known as Abell 1060, the Hydra galaxy cluster is one of three large galaxy clusters within 200 million light-years of the Milky Way. In the nearby universe, galaxies are gravitationally bound into clusters which themselves are loosely bound into superclusters that in turn are seen to align over even larger scales. At a distance of 100 million light-years this picture would be about 1.3 million light-years across.

Image credit: Angus Lau
Spiral Galaxy NGC 1672 from Hubble (2012-05-13)

Many spiral galaxies have bars across their centers.  Even our own Milky Way Galaxy is thought to have a modest central bar. Prominently barred spiral galaxy NGC 1672, pictured above, was captured in spectacular detail in image taken by the orbiting Hubble Space Telescope. Visible are dark filamentary dust lanes, young clusters of bright blue stars, red emission nebulas of glowing hydrogen gas, a long bright bar of stars across the center, and a bright active nucleus that likely houses a supermassive black hole.  Light takes about 60 million years to reach us from NGC 1672, which spans about 75,000 light years across. NGC 1672, which appears toward the constellation of the Dolphinfish (Dorado), is being studied to find out how a spiral bar contributes to star formation in a galaxy's central regions.    Follow APOD: On Facebook or Google+
Virtual Flight Over Asteroid Vesta (2012-05-14)

What would it be like to fly over the asteroid Vesta? Animators from the German Aerospace Center recently took actual images and height data from NASA's Dawn mission currently visiting Vesta to generate such a virtual movie. The above video begins with a sequence above Divalia Fossa, an unusual pair of troughs running parallel over heavily cratered terrain. Next, the virtual spaceship explores Vesta's 60-km Marcia Crater, showing numerous vivid details. Last, Dawn images were digitally recast with exaggerated height to better reveal Vesta's 5-km high mountain Aricia Tholus. Currently, Dawn is rising away from Vesta after being close enough to obtain the  most detailed surface images and gravity measurements of the Solar System's second largest asteroid. In August, Dawn is scheduled to blast away from Vesta and head toward Ceres, the Solar System's largest asteroid.   Help Evaluate APOD: Do the pictures (or videos) on APOD make you more interested in reading the text?
All the Water on Planet Earth (2012-05-15)

How much of planet Earth is made of water? Very little, actually. Although oceans of water cover about 70 percent of Earth's surface, these oceans are shallow compared to the Earth's radius. The above illustration shows what would happen if all of the water on or near the surface of the Earth were bunched up into a ball. The radius of this ball would be only about 700 kilometers, less than half the radius of the Earth's Moon, but slightly larger than Saturn's moon Rhea which, like many moons in our outer Solar System, is mostly water ice. How even this much water came to be on the Earth and whether any significant amount is trapped far beneath Earth's surface remain topics of research.   Poll: Have you seen today's APOD image before?

Image credit: Woods Hole Oceanographic Institution
Star Formation in the Tarantula Nebula (2012-05-16)

The largest, most violent star forming region known in the whole Local Group of galaxies lies in our neighboring galaxy the Large Magellanic Cloud (LMC).  Were the Tarantula Nebula at the distance of the Orion Nebula -- a local star forming region -- it would take up fully half the sky.  Also called 30 Doradus, the red and pink gas indicates a massive emission nebula, although supernova remnants and dark nebula also exist there.  The bright knot of stars left of center is called R136 and contains many of the most massive, hottest, and brightest stars known.  The above image is one of the largest mosaics ever created by observations of the Hubble Space Telescope and has revealed unprecedented details of this enigmatic star forming region.  The image is being released to celebrate the 22nd anniversary of Hubble's launch.   Astronomy Seminar of the Week: The Great Debate, Part I
Herschel's Cygnus X (2012-05-17)

The Herschel Space Observatory's infrared view of Cygnus X spans some 6x2 degrees across one of the closest, massive star forming regions in the plane of our Milky Way galaxy. In fact, the rich stellar nursery already holds the massive star cluster known as the Cygnus OB2 association. But those stars are more evident by the region cleared by their energetic winds and radiation near the bottom center of this field, and are not detected by Herschel instruments operating at long infrared wavelengths. Herschel does reveal the region's complex filaments of cool gas and dust that lead to dense locations where new massive stars are forming. Cygnus X lies some 4500 light-years away toward the heart of the northern constellation of the Swan. At that distance this picture would be almost 500 light-years wide.
GALEX: The Andromeda Galaxy (2012-05-18)

A mere 2.5 million light-years away, the Andromeda Galaxy really is just next door as large galaxies go. So close, and spanning some 260,000 light-years, it took 11 different image fields from the Galaxy Evolution Explorer (GALEX) satellite's telescope to produce this gorgeous portrait of the spiral galaxy in ultraviolet light. While its spiral arms stand out in visible light images of Andromeda (also known as M31), the arms look more like rings in the GALEX ultraviolet view, dominated by hot, young, massive stars. As sites of intense star formation, the rings have been interpreted as evidence Andromeda collided with its smaller neighboring elliptical galaxy M32 more than 200 million years ago. The large Andromeda galaxy and our own Milky Way are the dominant members of the local galaxy group.
Annular Solar Eclipse (2012-05-19)

Tomorrow, May 20, the Moon's shadow will race across planet Earth. Observers within the 240-300 kilometer wide shadow track will be able to witness an annular solar eclipse as the Moon's apparent size is presently too small to completely cover the Sun. Heading east over a period of 3.5 hours, the shadow path will begin in southern China, cross the northern Pacific, and reach well into North America, crossing the US west coast in southern Oregon and northern California. Along the route, Tokyo residents will be just 10 kilometers north of the path's center line. Of course a partial eclipse will be visible from a much larger area within North America, the Pacific, and eastern Asia. This safely filtered telescopic picture was taken during the annular eclipse of January 15, 2010 from the city of Kanyakumari at the southern tip of India.

Image credit: Mikael
Svalgaard
A Partial Eclipse Over Manila Bay (2012-05-20)

What's happened to the setting Sun?  An eclipse! In early 2009, the Moon eclipsed part of the Sun as visible from parts of Africa, Australia, and Asia.  In particular the above image, taken from the Mall of Asia seawall, caught a partially eclipsed Sun setting over Manila Bay in the Philippines.  Piers are visible in silhouette in the foreground.  Eclipse chasers and well placed sky enthusiasts captured many other interesting and artistic images of the year's only annular solar eclipse, including movies, eclipse shadow arrays, and rings of fire. Today parts of the Sun again will become briefly blocked by the Moon, again visible to some as a partial eclipse of a setting Sun. A small swath of Earth, however, will be exposed to the unusual ring of fire effect when the Moon is completely surrounded by the glowing light of the slightly larger Sun.   APOD Collection: Images of Past Partial Solar Eclipses  Gallery: Images of Today's Eclipse

Image credit: Armando Lee
(Astron. League Philippines), F. Naelga Jr.,
100 Hours of Astronomy
(IYA2009)
A Close Pass of Saturn's Moon Dione (2012-05-21)

What's that past Dione? When making its closest pass yet of Saturn's moon Dione late last year, the robotic Cassini spacecraft snapped this far-ranging picture featuring Dione, Saturn's rings, and the two small moons Epimetheus and Prometheus. The above image captures part of the heavily cratered snow-white surface of the 1,100 kilometer wide Dione, the thinness of Saturn's rings, and the comparative darkness of the smaller moon Epimetheus.  The image was taken when Cassini was only about 100,000 kilometers from the large icy moon. Future events in Cassini's continuing exploration of Saturn and its moons include tomorrow's flyby of Titan and imaging the distant Earth passing behind Saturn in June.   Gallery: Images of Yesterday's Eclipse
A Partial Solar Eclipse over Texas (2012-05-22)

It was a typical Texas sunset except that most of the Sun was missing.  The location of the missing piece of the Sun was not a mystery -- it was behind the Moon.  Sunday night's partial eclipse of the Sun by the Moon turned into one of the best photographed astronomical events in history.  Gallery after online gallery is posting just one amazing eclipse image after another. Pictured above is possibly one of the more interesting posted images -- a partially eclipsed Sun setting in a reddened sky behind brush and a windmill. The image was taken Sunday night from about 20 miles west of Sundown, Texas, USA, just after the ring of fire effect was broken by the Moon moving away from the center of the Sun. Coming early next month is an astronomical event that holds promise to be even more photographed -- the last partial eclipse of the Sun by Venus until the year 2117.   New Image Feeds: APOD River on Google Plus and APOD Sky on Facebook

Image credit: Jimmy Westlake 
(Colorado Mountain College) & Linda Westlake
SpaceX Falcon 9 Launches to the Space Station (2012-05-23)

This fire-breathing Dragon can fly. Pictured above yesterday, SpaceX Corporation's Falcon 9 rocket capped with a Dragon spacecraft   lifted off from Cape Canaveral, Florida, USA. The successful launch was significant not only because it demonstrated that a private company has the ability to re-supply the International Space Station (ISS), but also that spaceflight has taken a significant step away from being an endeavor that only big governments can do with public money. If all continues as planned, the robotic Dragon will dock with the ISS this weekend. Over the next two weeks, the ISS Expedition 31 crew will then unload Dragon and refill it with used scientific equipment. In about three weeks, the ISS's robotic arm will then undock Dragon and move it to where it can fire its rockets.  Soon thereafter the Dragon capsule is expected to reenter the Earth's atmosphere, deploy its parachutes, splash down in the Pacific Ocean off the coast of California, and be recovered.   Now 444 Codes:  The Astrophysics Source Code Library