juliensimon/nasa-apod huggingface dataset:
M27: The Dumbbell Nebula (2014-09-14)

The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core. M27 is one of the brightest planetary nebulae on the sky, and can be seen toward the constellation of the Fox (Vulpecula) with binoculars. It takes light about 1000 years to reach us from M27,  shown above in colors emitted by hydrogen and oxygen. Understanding the physics and significance of M27 was well beyond 18th century science. Even today, many things remain mysterious about bipolar planetary nebula like M27, including the physical mechanism that expels a low-mass star's gaseous outer-envelope, leaving an X-ray hot white dwarf.

Image credit: Bill Snyder
(Bill
Snyder Photography)
62 Kilometers above Comet Churyumov-Gerasimenko (2014-09-15)

Spacecraft Rosetta continues to approach, circle, and map Comet Churyumov-Gerasimenko. Crossing the inner Solar System for ten years to reach the vicinity of the comet last month, the robotic spacecraft continues to image the unusual double-lobed comet nucleus. The reconstructed-color image featured, taken about 10 days ago, indicates how dark this comet nucleus is.  On the average, the comet's surface reflects only about four percent of impinging visible light, making it as dark as coal.  Comet 67P/Churyumov�Gerasimenko spans about four kilometers in length and has a surface gravity so low that an astronaut could jump off of it.  In about two months, Rosetta is scheduled to release the first probe ever to attempt a controlled landing on a comet's nucleus.   Astronomers: Has an APOD image ever helped your research?

Image credit: Elisabetta Bonora & Marco Faccin 
(Alive Universe Images)
Milky Way above Atacama Salt Lagoon (2014-09-16)

Galaxies, stars, and a serene reflecting pool combine to create this memorable land and skyscape. The featured panorama is a 12-image mosaic taken last month from the Salar de Atacama salt flat in northern Chile. The calm water is Laguna Cejar, a salty lagoon featuring a large central sinkhole.  On the image left, the astrophotographer's fiancee is seen capturing the same photogenic scene. The night sky is lit up with countless stars, the Large and Small Magellanic Cloud galaxies on the left, and the band of our Milky Way galaxy running diagonally up the right. The Milky Way may appear to be causing havoc at the horizon, but those are just the normal lights of a nearby town.   Follow APOD on: Facebook,  Google Plus, or Twitter

Image credit: Alex Tudorica
(AIfA, U. Bonn)
Aurora over Maine (2014-09-17)

It has been a good week for auroras. Earlier this month active sunspot region 2158 rotated into view and unleashed a series of flares and plasma ejections into the Solar System during its journey across the Sun's disk. In particular, a pair of Coronal Mass Ejections (CMEs) impacted the Earth's magnetosphere toward the end of last week, creating the most intense geomagnetic storm so far this year.  Although power outages were feared by some, the most dramatic effects of these impacting plasma clouds were auroras seen as far south as Wisconsin, USA. In the featured image taken last Friday night, rays and sheets of multicolored auroras were captured over Acadia National Park, in Maine, USA.  Since another CME plasma cloud is currently approaching the Earth, tonight offers another good chance to see an impressive auroral display.   Almost Hyperspace: Random APOD Generator

Image credit: Jeremy P. Gray
Cocoon Nebula Wide Field (2014-09-18)

In this crowded starfield covering over 2 degrees within the high flying constellation Cygnus, the eye is drawn to the Cocoon Nebula. A compact star forming region, the cosmic Cocoon punctuates a long trail of obscuring interstellar dust clouds. Cataloged as IC 5146, the nebula is nearly 15 light-years wide, located some 4,000 light years away. Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by the young, hot stars and blue, dust-reflected starlight at the edge of an otherwise invisible molecular cloud. In fact, the bright star near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it clears out a cavity in the molecular cloud's star forming dust and gas. But the long dusty filaments that appear dark in this visible light image are themselves hiding stars in the process of formation that can be seen seen at infrared wavelengths.

Image credit: Federico Pelliccia
Potentially Habitable Moons (2014-09-19)

For astrobiologists, these may be the four most tantalizing moons in our Solar System. Shown at the same scale, their exploration by interplanetary spacecraft has launched the idea that moons, not just planets, could have environments supporting life. The Galileo mission to Jupiter discovered Europa's global subsurface ocean of liquid water and indications of Ganymede's interior seas. At Saturn, the Cassini probe detected erupting fountains of water ice from Enceladus indicating warmer subsurface water on even that small moon, while finding surface lakes of frigid but still liquid hydrocarbons beneath the dense atmosphere of large moon Titan. Now looking beyond the Solar System, new research suggests that sizable exomoons, could actually outnumber exoplanets in stellar habitable zones. That would make moons the most common type of habitable world in the Universe.
Shoreline of the Universe (2014-09-20)

Against dark rifts of interstellar dust, the ebb and flow of starlight along the Milky Way looks like waves breaking on a cosmic shore in this night skyscape. Taken with a digital camera from the dunes of Hatteras Island, North Carolina, planet Earth, the monochrome image is reminiscent of the time when sensitive black and white film was a popular choice for dimly lit night- and astro-photography. Looking south, the bright stars of Sagittarius and Scorpius are near the center of the frame. Wandering Mars, Saturn, and Zubenelgenubi (Alpha Librae) form the compact triangle of bright celestial beacons farther right of the galaxy's central bulge. Of course, the evocative black and white beach scene could also be from that vintage 1950s scifi movie you never saw, "It Came From Beyond the Dunes."

Image credit: Bill Dickinson
Saturn at Equinox (2014-09-21)

How would Saturn look if its ring plane pointed right at the Sun? Before August 2009, nobody knew.  Every 15 years, as seen from Earth, Saturn's rings point toward the Earth and appear to disappear. The disappearing rings are no longer a mystery -- Saturn's rings are known to be so thin and the Earth is so near the Sun that when the rings point toward the Sun, they also point nearly edge-on at the Earth. Fortunately, in this third millennium, humanity is advanced enough to have a spacecraft that can see the rings during equinox from the side. In August 2009, that Saturn-orbiting spacecraft, Cassini, was able to snap a series of unprecedented pictures of Saturn's rings during equinox. A digital composite of 75 such images is shown above. The rings appear unusually dark, and a very thin ring shadow line can be made out on Saturn's cloud-tops.  Objects sticking out of the ring plane are brightly illuminated and cast long shadows.  Inspection of these images is helping humanity to understand the specific sizes of Saturn's ring particles and the general dynamics of orbital motion. This week, Earth undergoes an equinox.   APOD Wall Calendar: Moons and Planets
Earth at Equinox (2014-09-22)

rth is at equinox. Over the next 24 hours, day and night have nearly equal duration all over planet Earth. Technically, equinox transpires at 2:29 am Universal Time tomorrow, but this occurs today in North and South America. This September equinox signal that winter is approaching in the northern hemisphere, and summer is approaching in the south. At equinox, the dividing line between the sunlit half of Earth and the nighttime half of Earth temporarily passes through Earth's north and south spin poles. This dividing line is shown in clear detail in the featured video, taken by the Russian meteorological satellite Elektro-L during last year's September equinox.  The Elektro-L satellite is in geostationary orbit over one spot on Earth's equator and always points directly toward the Earth.  The featured video shows a time lapse for an entire day surrounding the equinox, with a new image taken every 30 minutes. Cloud motions are visible as well as the reflection of the Sun are visible as the equinox day progressed. The next Earth equinox is scheduled for March.   Almost Hyperspace: Random APOD Generator
Aurora and Volcanic Light Pillar (2014-09-23)

That's no sunset. And that thin red line just above it -- that's not a sun pillar. The red glow on the horizon originates from a volcanic eruption, and the red line is the eruption's reflection from fluttering atmospheric ice crystals. This unusual volcanic light pillar was captured over Iceland earlier this month. The featured scene looks north from J�kuls�rl�n toward the erupting volcano B�r�arbunga in the Holuhraun lava field. Even the foreground sky is picturesque, with textured grey clouds in the lower atmosphere, shimmering green aurora in the upper atmosphere, and bright stars far in the distance. Although the last eruption from Holuhraun was in 1797, the present volcanic activity continues.   APOD Wall Calendar: Land and Skyscapes

Image credit: Stéphane Vetter
(Nuits sacrées)
The Lagoon Nebula in Stars Dust and Gas (2014-09-24)

The large majestic Lagoon Nebula is home for many young stars and hot gas. Spanning 100 light years across while lying only about 5000 light years distant, the Lagoon Nebula is so big and bright that it can be seen without a telescope toward the constellation of Sagittarius.  Many bright stars are visible from NGC 6530, an open cluster that formed in the nebula only several million years ago. The greater nebula, also known as M8 and NGC 6523, is named "Lagoon" for the band of dust seen to the left of the open cluster's center. A bright knot of gas and dust in the nebula's center is known as the Hourglass Nebula. The featured picture is a newly processed panorama of M8, capturing five times the diameter of the Moon. Star formation continues in the Lagoon Nebula as witnessed by the many globules that exist there.   APOD Wall Calendar: Nebulas and Star Clusters

Image credit: Remus Chua
(Celestial Portraits)
NGC 206 and the Star Clouds of Andromeda (2014-09-25)

The large stellar association cataloged as NGC 206 is nestled within the dusty arms of the neighboring Andromeda galaxy. Also known as M31, the spiral galaxy is a mere 2.5 million light-years away. NGC 206 is near top center in this gorgeous close-up of the southwestern extent of Andromeda's disk, a remarkable composite of data from space and ground-based observatories. The bright, blue stars of NGC 206 indicate its youth. In fact, its youngest massive stars are less than 10 million years old. Much larger than the open or galactic clusters of young stars in the disk of our Milky Way galaxy, NGC 206 spans about 4,000 light-years. That's comparable in size to the giant stellar nurseries NGC 604 in nearby spiral M33 and the Tarantula Nebula, in the Large Magellanic Cloud. Star forming sites within Andromeda are revealed by the telltale reddish emission from clouds of ionized hydrogen gas.

Image credit: Subaru
Telescope  (NAOJ), 


Hubble Space
Telescope,


Local Group Galaxy Survey (Phil Massey, PI), Mayall 4-meter

,

Robert
Gendler
MAVEN at Mars (2014-09-26)

Launched on November 18, 2013, the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft completed its interplanetary voyage September 21, captured into a wide, elliptical orbit around Mars. MAVEN's imaging ultraviolet spectrograph has already begun its planned exploration of the Red Planet's upper atmosphere, acquiring this image data from an altitude of 36,500 kilometers. In false color, the three ultraviolet wavelength bands show light reflected from atomic hydrogen (in blue), atomic oxygen (in green) and the planet's surface (in red). Low mass atomic hydrogen is seen to extend thousands of kilometers into space, with the cloud of more massive oxygen atoms held closer by Mars' gravity. Both are by products of the breakdown of water and carbon dioxide in Mars' atmosphere and the MAVEN data can be used to determine the rate of water loss over time. In fact, MAVEN is the first mission dedicated to exploring Mars' tenuous upper atmosphere, ionosphere and interactions with the Sun and solar wind. But the most recent addition to the fleet of spacecraft from planet Earth now in martian orbit is MOM.
A Launch and a Landing (2014-09-27)

Taken from an Atlantic beach, Cape Canaveral, planet Earth, four identically framed digital images are combined in this night skyscape. Slightly shifted short star trails dot the sky, but the exposure times were adjusted to follow the flight of a Falcon 9 rocket. The September 21 launch delivered a Dragon X capsule filled with supplies to the International Space Station. Above the bright flare seen just after launch, the rocket's first stage firing trails upward from the left. After separation, the second stage burn begins near center with the vehicle climbing toward low Earth orbit. At the horizon, the flare near center records the re-ignition and controlled descent of the Falcon 9's first stage to a soft splashdown off the coast.

Image credit: Mike Killian
Two Black Holes Dancing in 3C 75 (2014-09-28)

What's happening at the center of active galaxy 3C 75?  The two bright sources at the center of this composite x-ray (blue)/ radio (pink) image are co-orbiting supermassive black holes powering the giant radio source 3C 75. Surrounded by multimillion degree x-ray emitting gas, and blasting out jets of relativistic particles the supermassive black holes are separated by 25,000 light-years. At the cores of two merging galaxies in the Abell 400 galaxy cluster they are some 300 million light-years away. Astronomers conclude that these two supermassive black holes are bound together by gravity in a binary system in part because the jets' consistent swept back appearance is most likely due to their common motion as they speed through the hot cluster gas at 1200 kilometers per second. Such spectacular cosmic mergers are thought to be common in crowded galaxy cluster environments in the distant universe. In their final stages the mergers are expected to be intense sources of gravitational waves.    APOD Wall Calendar: Galaxies
Unusual Rocks near Pahrump Hills on Mars (2014-09-29)

How did these Martian rocks form? As the robotic Curiosity rover has approached Pahrump Hills on Mars, it has seen an interesting and textured landscape dotted by some unusual rocks. The featured image shows a curiously round rock spanning about two centimeters across. Seemingly a larger version of numerous spherules dubbed blueberries found by the Opportunity rover on Mars in 2004, what caused this roundness remains unknown. Possibilities include frequent tumbling in flowing water, sprayed molten rock in a volcanic eruption, or a concretion mechanism. The inset image, taken a few days later, shows another small but unusually shaped rock structure. As Curiosity rolls around and up Mount Sharp, different layers of the landscape will be imaged and studied to better understand the ancient history of the region and to investigate whether Mars could once have harbored life.   APOD Wall Calendar: Moons and Planets
A Full Circle Rainbow over Australia (2014-09-30)

Have you ever seen an entire rainbow? From the ground, typically, only the top portion of a rainbow is visible because directions toward the ground have fewer raindrops. From the air, though, the entire 360 degree circle of a rainbow is more commonly visible. Pictured here, a full circle rainbow was captured over Cottesloe Beach near Perth, Australia last year by a helicopter flying between a setting sun and a downpour. An observer-dependent phenomenon primarily caused by the internal reflection of sunlight by raindrops, the 84-degree diameter rainbow followed the helicopter, intact, for about 5 kilometers. As a bonus, a second rainbow that was more faint and color-reversed was visible outside the first.   APOD Astrophotographers: Has your work ever been used for scientific discovery?

Image credit: Colin Leonhardt 
(Birdseye View Photography)
The Butterfly Nebula from Hubble (2014-10-01)

The bright clusters and nebulae of planet Earth's night sky are often named for flowers or insects. Though its wingspan covers over 3 light-years, NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the dying central star of this particular planetary nebula has become exceptionally hot, shining brightly in ultraviolet light but hidden from direct view by a dense torus of dust.  This sharp close-up of the dying star's nebula was recorded in 2009 by the Hubble Space Telescope's Wide Field Camera 3, and is presented here in reprocessed colors.  Cutting across a bright cavity of ionized gas, the dust torus surrounding the central star is near the center of this view, almost edge-on to the line-of-sight. Molecular hydrogen has been detected in the hot star's dusty cosmic shroud. NGC 6302 lies about 4,000 light-years away in the arachnologically correct constellation of the Scorpion (Scorpius).    APOD Wall Calendar: Nebulas and Star Clusters

Image credit: Francesco Antonucci
The Bubble Nebula (2014-10-02)

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. Below and left of the Bubble's center is a hot, O star, several hundred thousand times more luminous and around 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 and associated cloud complex lie a mere 11,000 light-years away toward the boastful constellation Cassiopeia. This tantalizing view of the cosmic bubble is composed from narrowband image data, recording emission from the region's ionized hydrogen and oxygen atoms. To create the three color image, hydrogen and oxygen emission were used for red and blue and combined to create the green channel.

Image credit: Bernard Michaud
Aurora and Milky Way in a Little Sky (2014-10-03)

Stepping stones seem to lead to the Milky Way as it stretches across this little sky. Of course, the scene is really the northern hemisphere's autumnal equinox night. Water and sky are inverted by a top to bottom, around the horizon stereographic projection centered on the zenith above Lake Storsjön in Jämtland, Sweden. In the north the Milky Way arcs from east to west overhead as fall begins, but the season is also a good time for viewing aurora. Geomagnetic storms increase in frequency near the equinox and produce remarkable displays of northern lights at high latitudes, like the eerie greenish glow reflected in this watery cosmos.

Image credit: Göran Strand
Mars, Antares, Moon and Saturn (2014-10-04)

Mars, Antares, Moon, and Saturn are the brightest celestial beacons in this serene sky. The Sun's golden light is still scattered along the southwestern horizon though, captured after sunset on September 28. The evening gathering of wandering planets and Moon along with the bright star viewed as an equal to Mars and the Scorpion's Heart was enjoyed around planet Earth. But from the photographer's perspective looking across the calm waters of Lake Balaton, Hungary, they were joined by a more terrestrial sailboat mast light. Mast light, bright star, planets and Moon are all posing near the plane of the ecliptic.

Image credit: Tamas Ladanyi
A Total Lunar Eclipse Over Tajikistan (2014-10-05)

If the full Moon suddenly faded, what would you see? The answer during the total lunar eclipse of 2011 June was recorded in a dramatic time lapse video from Tajikistan. During a total lunar eclipse, the Earth moves between the Moon and the Sun, causing the moon to fade dramatically. The Moon never gets completely dark, though, since the Earth's atmosphere refracts some light. As the above video begins, the scene may appear to be daytime and sunlit, but actually it is a nighttime and lit by the glow of the full Moon. As the moon becomes eclipsed and fades, the wind dies down and background stars can be seen reflected in foreground lake. Most spectacularly, the sky surrounding the eclipsed moon suddenly appears to be full of stars and highlighted by the busy plane of our Milky Way Galaxy. The sequence repeats with a closer view, and the final image shows the placement of the eclipsed Moon near the Eagle, Swan, Trifid, and Lagoon nebulas. Nearly two hours after the eclipse started, the moon emerged from the Earth's shadow and its bright full glare again dominated the sky.  The next total lunar eclipse will occur this Wednesday.    APOD Wall Calendar: Moons and Planets

Image credit: Jean-Luc Dauvergne
(Ciel et Espace);
 Music:  Val�re Leroy &  Sophie Huet
(Space-Music)
Space Station Detector Finds Unexplained Positron Excess (2014-10-06)

Where did all these high energy positrons come from? The Alpha Magnetic Spectrometer (AMS-02) onboard the International Space Station (ISS) has been meticulously recording how often it is struck by both high energy electrons and positrons since 2011. After accumulating years of data, it has now become clear that there are significantly more positrons than expected at the highest energies detected.  The excess may have a very exciting and profound origin -- the annihilation of distant but previously undetected dark matter particles.  However, it is also possible that astronomical sources such as pulsars are creating the unexplained discrepancy. The topic remains a very active area of research.  Pictured here, the AMS is visible on the ISS just after being installed, with a US Space Shuttle docked on the far right, a Russian Soyuz capsule docked on the far left, and the blue Earth that houses all nations visible across the background.    Follow APOD on: Facebook,  Google Plus, or Twitter
From the Temple of the Sun to the Temple of the Moon (2014-10-07)

What connects the Sun to the Moon? Many answers have been given throughout history, but in the case of today's featured image, it appears to be the plane of our Milky Way Galaxy. The 16-image panorama was taken in Capitol Reef National Park, Utah, USA where two sandstone monoliths -- the Temple of the Moon on the right and the Temple of the Sun on the left -- rise dramatically from the desert. Each natural monument stands about 100 meters tall and survives from the Jurassic period 160 million years ago. Even older are many of the stars and nebulas that dot the celestial background, including the Andromeda Galaxy. Tomorrow the Earth will connect the Sun to the Moon by way of its shadow: a total lunar eclipse will be visible from many locations around the globe.   New: Follow APOD on Ello

Image credit: Dave Lane