Astronomy Picture of the Day RSS Feed

Star Formation in the Tarantula Nebula

Wed, 16 May 2012 13:06:01 GMT

Star Formation in the Tarantula Nebula 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
Tomorrow's picture: Cygnus X

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.

All the Water on Planet Earth

Tue, 15 May 2012 13:06:01 GMT

All the Water on Planet Earth 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 is 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?
Tomorrow's picture: open space

Virtual Flight Over Asteroid Vesta

Mon, 14 May 2012 13:06:01 GMT

Virtual Flight Over Asteroid Vesta 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?
Tomorrow's picture: waterless earth

Spiral Galaxy NGC 1672 from Hubble

Sun, 13 May 2012 13:06:01 GMT

Spiral Galaxy NGC 1672 from Hubble 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+
Tomorrow's picture: fly over vesta

The Hydra Cluster of Galaxies

Sat, 12 May 2012 13:06:03 GMT

The Hydra Cluster of Galaxies 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.

Sun vs. Super Moon

Fri, 11 May 2012 13:06:02 GMT

Sun vs. Super Moon 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.

Green Flash and Super Moon

Thu, 10 May 2012 13:06:01 GMT

Green Flash and Super Moon 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.

Shuttle Enterprise Over New York

Wed, 09 May 2012 13:06:01 GMT

Shuttle Enterprise Over New York 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
Tomorrow's picture: open space

The Light of Stars

Tue, 08 May 2012 14:46:17 GMT

The Light of Stars 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 Lopez 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 de Tiede, 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.
Tomorrow's picture: flying background

Supermoon Over Paris

Mon, 07 May 2012 13:06:00 GMT

Supermoon Over Paris 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
Tomorrow's picture: on the move

In the Center of the Omega Nebula

Sun, 06 May 2012 13:06:01 GMT

In the Center of the Omega Nebula 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.

Dark Mysteries: Astronomy Seminar of the Week
Tomorrow's picture: moving pan

Full Moonrise

Sat, 05 May 2012 13:06:00 GMT

Full Moonrise 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.

Fermi Epicycles: The Vela Pulsar's Path

Fri, 04 May 2012 13:06:00 GMT

Fermi Epicycles: The Vela Pulsar's Path Exploring 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.

M106 Close Up

Thu, 03 May 2012 13:06:01 GMT

M106 Close Up 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.

Saturn's Moon Helene in Color

Wed, 02 May 2012 13:06:01 GMT

Saturn's Moon Helene in Color 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
Tomorrow's picture: realm of the nebulae

Higgs Boson Explained by Cartoon

Tue, 01 May 2012 13:06:02 GMT

Higgs Boson Explained by Cartoon 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 be 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.

Tomorrow's picture: open space

Aurora Over Raufarhofn

Mon, 30 Apr 2012 18:22:04 GMT

Aurora Over Raufarhofn 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 Raufarhofn 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.

Tomorrow's picture: cartoon higgs

A Dangerous Sunrise on Gliese 876d

Sun, 29 Apr 2012 13:06:01 GMT

A Dangerous Sunrise on Gliese 876d 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.

Tomorrow's picture: apex aurora

Sutter's Mill Meteorite

Sat, 28 Apr 2012 13:06:02 GMT

Sutter's Mill Meteorite Last Sunday's bright fireball meteor falling through skies over California and Nevada produced sonic booms over a broad area around 7:21 am. Estimates indicate the meteor was about the size of a minivan. Astronomer Peter Jenniskens subsequently recovered these fragments of a crushed 4 gram meteorite, the second find from this meteor fall, in the parking lot of the Henningsen-Lotus state park, not far from Sutter's Mill. This is now known as the Sutter's Mill Meteorite, the location famous for its association with the California Gold Rush. The meteorite may well be astronomer's gold too, thought to be a rare CM type carbonaceous chondrite, a type rich in organic compounds and similar to the Murchison Meteorite. To trace the meteor's orbit, details of its breakup, and aid in locating more fragements, scientists are also searching for video records. Security cameras across a wide area could have accidently captured the fireball event near 7:21 am PDT on April 22; e.g. California (SF Bay Area, Los Angeles, near Redding) and Nevada (Reno area, Tonopah), even in southern parts of Oregon and near Salt Lake City in Utah. If you have video footage of the event, please use the contact information here.

Jupiter and the Moons of Earth

Fri, 27 Apr 2012 13:06:01 GMT

Jupiter and the Moons of Earth Planet Earth has many moons. Its largest artifical moon, the International Space Station, streaks through this lovely skyview with clouds in silhouette against the fading light of a sunset. Captured from Stuttgart, Germany last Sunday, the frame also includes Earth's largest natural satellite 1.5 days after its New Moon phase. Just below and left of the young crescent is Jupiter, another bright celestial beacon hovering near the western horizon in early evening skies. Only briefly, as seen from the photographer's location, Jupiter and these moons of Earth formed the remarkably close triple conjunction. Of course, Jupiter has many moons too. In fact, close inspection of the photo will reveal tiny pin pricks of light near the bright planet, large natural satellites of Jupiter known as Galilean moons.

Morning, Moon, and Mercury

Thu, 26 Apr 2012 13:06:00 GMT

Morning, Moon, and Mercury Last week Mercury wandered far to the west of the Sun. As the solar system's innermost planet neared its greatest elongation or greatest angle from the Sun (for this apparition about 27 degrees) it was joined by an old crescent Moon. The conjunction was an engaging sight for early morning risers in the southern hemisphere. There the pair rose together in predawn skies, climbing high above the horizon along a steeply inclined ecliptic plane. This well composed sequence captures the rising Moon and Mercury above the city lights of Brisbane in Queensland, Australia. A stack of digital images, it consists of an exposure made every 3 minutes beginning at 4:15 am local time on April 19. Mercury's track is at the far right, separated from the Moon's path by about 8 degrees.

Meteor Over Crater Lake

Wed, 25 Apr 2012 13:06:02 GMT

Meteor Over Crater Lake Did you see it? One of the more common questions during a meteor shower occurs because the time it takes for a meteor to flash is typically less than the time it takes for a head to turn. Possibly, though, the glory of seeing bright meteors shoot across and knowing that they were once small pebbles on another world might make it all worthwhile, even if your observing partner(s) could not share in every particular experience. Peaking over the past few days, a dark moonless sky allowed the Lyrids meteor shower to exhibit as many as 30 visible meteors per hour from some locations. A bright Lyrid meteor streaks above picturesque Crater Lake in Oregon, USA, in the above composite of nine exposures taken last week. Snow covers the foreground, while the majestic central band of our home galaxy arches well behind the serene lake. Other meteor showers this year include the Perseids in mid-August and the Leonids in mid-November, both expected to also dodge the glare of a bright Moon in 2012.

Tomorrow's picture: open space