Astronomy Picture of the Day (General/Chat)

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  • Astronomy Picture of the Day -- 62 Kilometers above Comet Churyumov-Gerasimenko

    09/14/2014 10:40:53 PM PDT · by SunkenCiv · 15 replies
    NASA ^ | September 15, 2014 | (see photo credit)
    Explanation: 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...
  • Astronomy Picture of the Day -- M27: The Dumbbell Nebula

    09/13/2014 9:28:43 PM PDT · by SunkenCiv · 16 replies
    NASA ^ | September 14, 2014 | (see photo credit)
    Explanation: 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...
  • Astronomy Picture of the Day -- Median Mashup: Hubble's Top 100

    09/13/2014 12:42:32 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | September 13, 2014 | (see photo credit)
    Explanation: Now, as you sip your cosmic latte you can view 100 Hubble Space Telescope images at the same time. The popular scenes of the cosmos as captured from low Earth orbit are all combined into this single digital presentation. To make it, Hubble's top 100 images were downloaded and resized to identical pixel dimensions. At each point the 100 pixel values were arranged from lowest to highest, and the middle or median value was chosen for the final image. The combined image results in a visual abstraction - light from across the Universe surrounded by darkness.
  • Astronomy Picture of the Day -- Supernova Remnant Puppis A

    09/13/2014 12:40:55 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | September 12, 2014 | (see photo credit)
    Explanation: Driven by the explosion of a massive star, supernova remnant Puppis A is blasting into the surrounding interstellar medium about 7,000 light-years away. At that distance, this remarkable false-color exploration of its complex expansion is about 180 light-years wide. It is based on the most complete X-ray data set so far from the Chandra and XMM/Newton observations, and infrared data from the Spitzer Space Telescope. In blue hues, the filamentary X-ray glow is from gas heated by the supernova's shock wave, while the infrared emission shown in red and green is from warm dust. The bright pastel tones trace...
  • Astronomy Picture of the Day -- Zodiacal Light before Dawn

    09/13/2014 12:36:34 PM PDT · by SunkenCiv · 7 replies
    NASA ^ | September 11, 2014 | (see photo credit)
    Explanation: You might not guess it, but sunrise was still hours away when this nightscape was taken, a view along the eastern horizon from a remote location in Chile's Atacama desert. Stretching high into the otherwise dark, starry sky the unusually bright conical glow is sunlight though, scattered by dust along the solar system's ecliptic plane . Known as Zodiacal light, the apparition is also nicknamed the "false dawn". Near center, bright star Aldebaran and the Pleiades star cluster seem immersed in the Zodiacal light, with Orion toward the right edge of the frame. Reddish emission from NGC 1499, the...
  • Astronomy Picture of the Day -- Laniakea: Our Home Supercluster of Galaxies

    09/13/2014 12:33:34 PM PDT · by SunkenCiv · 10 replies
    NASA ^ | September 10, 2014 | (see photo credit)
    Explanation: It is not only one of the largest structures known -- it is our home. The just-identified Laniakea Supercluster of galaxies contains thousands of galaxies that includes our Milky Way Galaxy, the Local Group of galaxies, and the entire nearby Virgo Cluster of Galaxies. The colossal supercluster is shown in the above computer-generated visualization, where green areas are rich with white-dot galaxies and white lines indicate motion towards the supercluster center. An outline of Laniakea is given in orange, while the blue dot shows our location. Outside the orange line, galaxies flow into other galatic concentrations. The Laniakea Supercluster...
  • Astronomy Picture of the Day -- An Aurora Cupcake with a Milky Way Topping

    09/13/2014 12:30:58 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | September 09, 2014 | (see photo credit)
    Explanation: This sky looked delicious. Double auroral ovals were captured above the town lights of Östersund, Sweden, last week. Pictured above, the green ovals occurred lower to the ground than violet aurora rays above, making the whole display look a bit like a cupcake. To top it off, far in the distance, the central band or our Milky Way Galaxy slants down from the upper left. The auroras were caused by our Sun ejecting plasma clouds into the Solar System just a few days before, ionized particles that subsequently impacted the magnetosphere of the Earth. Aurora displays may continue this...
  • Astronomy Picture of the Day -- Super Moon vs. Micro Moon

    09/13/2014 12:28:18 PM PDT · by SunkenCiv · 13 replies
    NASA ^ | September 08, 2014 | (see photo credit)
    Explanation: What is so super about tomorrow's supermoon? Tomorrow, a full moon will occur that appears slightly larger and brighter than usual. The reason is that the Moon's fully illuminated phase occurs within a short time from perigee - when the Moon is its closest to the Earth in its elliptical orbit. Although the precise conditions that define a supermoon vary, given one definition, tomorrow's will be the third supermoon of the year -- and the third consecutive month that a supermoon occurs. One reason supermoons are popular is because they are so easy to see -- just go outside...
  • Astronomy Picture of the Day -- Full Moon Silhouettes

    09/06/2014 10:10:29 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | September 07, 2014 | (see photo credit)
    Explanation: Have you ever watched the Moon rise? The slow rise of a nearly full moon over a clear horizon can be an impressive sight. One impressive moonrise was imaged in early 2013 over Mount Victoria Lookout in Wellington, New Zealand. With detailed planning, an industrious astrophotographer placed a camera about two kilometers away and pointed it across the lookout to where the Moon would surely soon be making its nightly debut. The above single shot sequence is unedited and shown in real time -- it is not a time lapse. People on Mount Victoria Lookout can be seen in...
  • Astronomy Picture of the Day -- Moonbow Beach

    09/06/2014 4:52:36 AM PDT · by SunkenCiv · 6 replies
    NASA ^ | September 06, 2014 | (see photo credit)
    Explanation: Like a rainbow at night, a beautiful moonbow shines above the western horizon in this deserted beach scene from Molokai Island, Hawaii, USA, planet Earth. Captured last June 17 in early morning hours, the lights along the horizon are from Honolulu and cities on the island of Oahu some 30 miles away. So where was the Moon? A rainbow is produced by sunlight internally reflected in rain drops from the direction opposite the Sun back toward the observer. As the light passes from air to water and back to air again, longer wavelengths are refracted (bent) less than shorter...
  • Astronomy Picture of the Day -- A Sagittarius Starscape

    09/06/2014 4:49:49 AM PDT · by SunkenCiv · 3 replies
    NASA ^ | September 05, 2014 | (see photo credit)
    Explanation: This rich starscape spans nearly 7 degrees on the sky, toward the Sagittarius spiral arm and the center of our Milky Way galaxy. A telescopic mosaic, it features well-known bright nebulae and star clusters cataloged by 18th century cosmic tourist Charles Messier. Still popular stops for skygazers M16, the Eagle (far right), and M17, the Swan (near center) nebulae are the brightest star-forming emission regions. With wingspans of 100 light-years or so, they shine with the telltale reddish glow of hydrogen atoms from over 5,000 light-years away. Colorful open star cluster M25 near the upper left edge of the...
  • Astronomy Picture of the Day -- Cloud, Clusters and

    09/04/2014 4:37:42 AM PDT · by SunkenCiv · 6 replies
    NASA ^ | September 04, 2014 | (see photo credit)
    Explanation: On October 19th, a good place to watch Comet Siding Spring will be from Mars. Then, this inbound visitor (C/2013 A1) to the inner solar system, discovered in January 2013 by Robert McNaught at Australia's Siding Spring Observatory, will pass within 132,000 kilometers of the Red Planet. That's a near miss, equivalent to just over 1/3 the Earth-Moon distance. Great views of the comet for denizens of planet Earth's southern hemisphere are possible now, though. This telescopic snapshot from August 29 captured the comet's whitish coma and arcing dust tail sweeping through southern skies. The fabulous field of view...
  • Astronomy Picture of the Day -- M6: The Butterfly Cluster

    09/04/2014 4:33:28 AM PDT · by SunkenCiv · 2 replies
    NASA ^ | September 03, 2014 | (see photo credit)
    Explanation: To some, the outline of the open cluster of stars M6 resembles a butterfly. M6, also known as NGC 6405, spans about 20 light-years and lies about 2,000 light years distant. M6, pictured above, can best be seen in a dark sky with binoculars towards the constellation of the Scorpion (Scorpius), coving about as much of the sky as the full moon. Like other open clusters, M6 is composed predominantly of young blue stars, although the brightest star is nearly orange. M6 is estimated to be about 100 million years old. Determining the distance to clusters like M6 helps...
  • Astronomy Picture of the Day -- Holometer: A Microscope into Space and Time

    09/04/2014 4:29:41 AM PDT · by SunkenCiv · 4 replies
    NASA ^ | September 02, 2014 | (see photo credit)
    Explanation: How different are space and time at very small scales? To explore the unfamiliar domain of the miniscule Planck scale -- where normally unnoticeable quantum effects might become dominant -- a newly developed instrument called the Fermilab Holometer has begun operating at the Fermi National Accelerator Laboratory (Fermilab) near Chicago, Illinois, USA. The instrument seeks to determine if slight but simultaneous jiggles of a mirror in two directions expose a fundamental type of holographic noise that always exceeds a minimum amount. Pictured above is one of the end mirrors of a Holometer prototype. Although the discovery of holographic noise...
  • Astronomy Picture of the Day -- Airglow Ripples over Tibet

    09/01/2014 12:50:51 PM PDT · by SunkenCiv · 8 replies
    NASA ^ | September 01, 2014 | (see photo credit)
    Explanation: Why would the sky look like a giant target? Airglow. Following a giant thunderstorm over Bangladesh in late April, giant circular ripples of glowing air appeared over Tibet, China, as pictured above. The unusual pattern is created by atmospheric gravity waves, waves of alternating air pressure that can grow with height as the air thins, in this case about 90 kilometers up. Unlike auroras powered by collisions with energetic charged particles and seen at high latitudes, airglow is due to chemiluminescence, the production of light in a chemical reaction. More typically seen near the horizon, airglow keeps the night...
  • Astronomy Picture of the Day -- Space Shuttle and Space Station Photographed Together

    08/30/2014 11:05:59 PM PDT · by SunkenCiv · 25 replies
    NASA ^ | August 31, 2014 | (see photo credit)
    Explanation: How was this picture taken? Usually, pictures of the shuttle, taken from space, are snapped from the space station. Commonly, pictures of the space station are snapped from the shuttle. How, then, can there be a picture of both the shuttle and the station together, taken from space? The answer is that during the Space Shuttle Endeavour's last trip to the International Space Station in 2011 May, a supply ship departed the station with astronauts that captured a series of rare views. The supply ship was the Russian Soyuz TMA-20 which landed in Kazakhstan later that day. The above...
  • Astronomy Picture of the Day -- The Starry Sky under Hollow Hill

    08/30/2014 12:02:41 PM PDT · by SunkenCiv · 7 replies
    NASA ^ | August 30, 2014 | (see photo credit)
    Explanation: Look up in New Zealand's Hollow Hill Cave and you might think you see a familiar starry sky. And that's exactly what Arachnocampa luminosa are counting on. Captured in this long exposure, the New Zealand glowworms scattered across the cave ceiling give it the inviting and open appearance of a clear, dark night sky filled with stars. Unsuspecting insects fooled into flying too far upwards get trapped in sticky snares the glowworms create and hang down to catch food. Of course professional astronomers wouldn't be so easily fooled, although that does look a lot like the Coalsack Nebula and...
  • Astronomy Picture of the Day -- The Wizard Nebula

    08/28/2014 10:03:52 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | August 29, 2014 | (see photo credit)
    Explanation: Open star cluster NGC 7380 is still embedded in its natal cloud of interstellar gas and dust popularly known as the Wizard Nebula. Seen with foreground and background stars along the plane of our Milky Way galaxy it lies some 8,000 light-years distant, toward the constellation Cepheus. A full moon would easily fit inside this telescopic view of the 4 million year young cluster and associated nebula, normally much too faint to be seen by eye. Made with telescope and camera firmly planted on Earth, the image reveals multi light-year sized shapes and structures within the Wizard in a...
  • Astronomy Picture of the Day -- Messier 20 and 21

    08/28/2014 7:32:17 PM PDT · by SunkenCiv · 3 replies
    NASA ^ | August 28, 2014 | (see photo credit)
    Explanation: The beautiful Trifid Nebula, also known as Messier 20, is easy to find with a small telescope in the nebula rich constellation Sagittarius. About 5,000 light-years away, the colorful study in cosmic contrasts shares this well-composed, nearly 1 degree wide field with open star cluster Messier 21 (top right). Trisected by dust lanes the Trifid itself is about 40 light-years across and a mere 300,000 years old. That makes it one of the youngest star forming regions in our sky, with newborn and embryonic stars embedded in its natal dust and gas clouds. Estimates of the distance to open...
  • Astronomy Picture of the Day -- Milky Way over Yellowstone

    08/28/2014 7:20:51 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | August 27, 2014 | (see photo credit)
    Explanation: The Milky Way was not created by an evaporating lake. The colorful pool of water, about 10 meters across, is known as Silex Spring and is located in Yellowstone National Park in Wyoming, USA. Illuminated artificially, the colors are caused by layers of bacteria that grow in the hot spring. Steam rises off the spring, heated by a magma chamber deep underneath known as the Yellowstone hotspot. Unrelated and far in the distance, the central band of our Milky Way Galaxy arches high overhead, a band lit by billions of stars. The above picture is a 16-image panorama taken...
  • Astronomy Picture of the Day -- Flying Past Neptune's Moon Triton

    08/28/2014 6:55:04 PM PDT · by SunkenCiv · 14 replies
    NASA ^ | August 26, 2014 | (see photo credit)
    Explanation: What would it look like to fly past Triton, the largest moon of planet Neptune? Only one spacecraft has ever done this -- and now, for the first time, images of this dramatic encounter have been gathered into a movie. On 1989 August 25, the Voyager 2 spacecraft shot through the Neptune system with cameras blazing. Triton is slightly smaller than Earth's Moon but has ice volcanoes and a surface rich in frozen nitrogen. The first sequence in the video shows Voyager's approach to Triton, which, despite its unusual green tint, appears in approximately true color. The mysterious terrain...
  • Astronomy Picture of the Day -- Arp 188 and the Tadpole's Tail

    08/24/2014 9:23:44 PM PDT · by SunkenCiv · 11 replies
    NASA ^ | August 25, 2014 | (see photo credit)
    Explanation: Why does this galaxy have such a long tail? In this stunning vista, based on image data from the Hubble Legacy Archive, distant galaxies form a dramatic backdrop for disrupted spiral galaxy Arp 188, the Tadpole Galaxy. The cosmic tadpole is a mere 420 million light-years distant toward the northern constellation Draco. Its eye-catching tail is about 280 thousand light-years long and features massive, bright blue star clusters. One story goes that a more compact intruder galaxy crossed in front of Arp 188 - from right to left in this view - and was slung around behind the Tadpole...
  • Astronomy Picture of the Day -- Mercury's Transit: An Unusual Spot on the Sun

    08/24/2014 1:39:14 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | August 24, 2014 | (see photo credit)
    Explanation: What's that dot on the Sun? If you look closely, it is almost perfectly round. The dot is the result of an unusual type of solar eclipse that occurred in 2006. Usually it is the Earth's Moon that eclipses the Sun. This time, the planet Mercury took a turn. Like the approach to New Moon before a solar eclipse, the phase of Mercury became a continually thinner crescent as the planet progressed toward an alignment with the Sun. Eventually the phase of Mercury dropped to zero and the dark spot of Mercury crossed our parent star. The situation could...
  • Astronomy Picture of the Day -- The Spectre of Veszprem

    08/23/2014 8:24:37 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | August 23, 2014 | (see photo credit)
    Explanation: The city of Veszprem, Hungary was only briefly haunted by this mysterious spectre. On the morning of August 11, its monstrous form hovered in the mist above municipal buildings near the town center. A clue to its true identity is offered by the photographer, though, who reports he took the picture from the top of a twenty story building with the rising Sun directly at his back. That special geometry suggests this is an example of an atmospheric phenomenon called the Glory or sometimes "the Spectre of the Brocken". Also seen from mountain tops and airplanes when looking opposite...
  • Astronomy Picture of the Day -- Comet Jacques, Heart and Soul

    08/23/2014 8:13:44 PM PDT · by SunkenCiv · 7 replies
    NASA ^ | August 22, 2014 | (see photo credit)
    Explanation: On July 13th, a good place to watch Comet Jacques was from Venus. Then, the recently discovered visitor (C/2014 E2) to the inner solar system passed within about 14.5 million kilometers of our sister planet. But the outbound comet will pass only 84 million kilometers from our fair planet on August 28 and is already a fine target for telescopes and binoculars. Two days ago Jacques' greenish coma and straight and narrow ion tail were captured in this telescopic snapshot, a single 2 minute long exposure with a modified digital camera. The comet is flanked by IC 1805 and...
  • Astronomy Picture of the Day -- Venus and Jupiter at Dawn

    08/23/2014 8:06:08 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | August 21, 2014 | (see photo credit)
    Explanation: On Monday morning, Venus and Jupiter gathered close in dawn skies, for some separated by about half the width of a full moon. It was their closest conjunction since 2000, captured here above the eastern horizon before sunrise. The serene and colorful view is from Istia beach near the city of Capoliveri on the island of Elba. Distant lights and rolling hills are along Italy's Tuscan coast. Of course, the celestial pair soon wandered apart. Brighter Venus headed lower, toward the eastern horizon and the glare of the Sun, while Jupiter continues to rise a little higher now in...
  • Astronomy Picture of the Day -- In the Center of the Lagoon Nebula

    08/23/2014 8:02:31 PM PDT · by SunkenCiv · 1 replies
    NASA ^ | August 20, 2014 | (see photo credit)
    Explanation: The center of the Lagoon Nebula is a whirlwind of spectacular star formation. Visible near the image center, at least two long funnel-shaped clouds, each roughly half a light-year long, have been formed by extreme stellar winds and intense energetic starlight. The tremendously bright nearby star, Herschel 36, lights the area. Walls of dust hide and redden other hot young stars. As energy from these stars pours into the cool dust and gas, large temperature differences in adjoining regions can be created generating shearing winds which may cause the funnels. This picture, spanning about 5 light years, combines images...
  • Astronomy Picture of the Day -- Contrasting Terrains on Comet Churyumov-Gerasimenko

    08/23/2014 7:58:55 PM PDT · by SunkenCiv · 21 replies
    NASA ^ | August 19, 2014 | (see photo credit)
    Explanation: Where should Philae land? As ESA's robotic spacecraft Rosetta circles toward Comet 67P/ Churyumov-Gerasimenko, a decision must eventually be made as to where its mechanical lander should attempt to touch-down. Reaching the comet earlier this month, Rosetta is sending back detailed pictures of the comet's unusual nucleus from which a smooth landing site will be selected. Pictured above, near the image top, the head of the comet's nucleus shows rugged grooves, while near the image bottom, the body shows a patch-work of areas sometimes separated by jagged hills. Some of the patch-work areas apparent on both the head and...
  • Astronomy Picture of the Day -- Star Trails Over Indonesia

    08/18/2014 7:00:19 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | August 18, 2014 | (see photo credit)
    Explanation: Both land and sky were restless. The unsettled land included erupting Mount Semeru in the distance, the caldera of steaming Mount Bromo on the left, flowing fog, and the lights of moving cars along roads that thread between hills and volcanoes in Bromo Tengger Semeru National Park in East Java, Indonesia. The stirring sky included stars circling the South Celestial Pole and a meteor streaking across the image right. The above 270-image composite was taken from King Kong Hill in mid-June over two hours, with a rising Moon lighting the landscape.
  • Astronomy Picture of the Day -- Jupiter and Venus from Earth

    08/17/2014 6:27:19 AM PDT · by SunkenCiv · 36 replies
    NASA ^ | August 17, 2014 | (see photo credit)
    Explanation: It was visible around the world. The sunset conjunction of Jupiter and Venus in 2012 was visible almost no matter where you lived on Earth. Anyone on the planet with a clear western horizon at sunset could see them. Pictured above in 2012, a creative photographer traveled away from the town lights of Szubin, Poland to image a near closest approach of the two planets. The bright planets were separated only by three degrees and his daughter striking a humorous pose. A faint red sunset still glowed in the background. Early tomorrow (Monday) morning, the two planets will pass...
  • Astronomy Picture of the Day -- No X-rays from SN 2014J

    08/16/2014 4:53:24 AM PDT · by SunkenCiv · 8 replies
    NASA ^ | August 16, 2014 | (see photo credit)
    Explanation: Last January, telescopes in observatories around planet Earth were eagerly used to watch the rise of SN 2014J, a bright supernova in nearby galaxy M82. Still, the most important observations may have been from orbit where the Chandra X-ray Observatory saw nothing. Identified as a Type Ia supernova, the explosion of SN2014J was thought to be triggered by the buildup of mass on a white dwarf star steadily accreting material from a companion star. That model predicts X-rays would be generated when the supernova blastwave struck the material left surrounding the white dwarf. But no X-rays were seen from...
  • Astronomy Picture of the Day -- A Luminous Night

    08/15/2014 6:54:51 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | August 15, 2014 | (see photo credit)
    Explanation: What shines in the world at night? Just visible to the eye, a rare electric blue glow spread along the shores of Victoria Lake on January 16, 2013. Against reflections of a light near the horizon, this digitally stacked long exposure recorded the bioluminescence of Noctiluca scintillans, plankton stimulated by the lapping waves. Above, the night skies of the Gippsland Lakes region, Victoria, Australia shine with a fainter greenish airglow. Oxygen atoms in the upper atmosphere, initially excited by ultraviolet sunlight, produce the more widely seen fading atmospheric chemiluminescence. Washed out by the Earth's rotation, the faint band of...
  • Astronomy Picture of the Day -- Surreal Moon

    08/14/2014 8:11:00 PM PDT · by SunkenCiv · 15 replies
    NASA ^ | August 14, 2014 | (see photo credit)
    Explanation: Big, bright, and beautiful, a Full Moon near perigee, the closest point in its elliptical orbit around our fair planet, rose on August 10. This remarkable picture records the scene with a dreamlike quality from the east coast of the United States. The picture is actually a composite of 10 digital frames made with exposures from 1/500th second to 1 second long, preserving contrast and detail over a much wider than normal range of brightness. At a perigee distance of a mere 356,896 kilometers, August's Full Moon was the closest, and so the largest and most super, of the...
  • Astronomy Picture of the Day -- Rings Around the Ring Nebula

    08/14/2014 8:08:39 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | August 13, 2014 | (see photo credit)
    Explanation: It is a familiar sight to sky enthusiasts with even a small telescope. There is much more to the Ring Nebula (M57), however, than can be seen through a small telescope. The easily visible central ring is about one light-year across, but this remarkably deep exposure - a collaborative effort combining data from three different large telescopes - explores the looping filaments of glowing gas extending much farther from the nebula's central star. This remarkable composite image includes narrowband hydrogen image, visible light emission, and infrared light emission. Of course, in this well-studied example of a planetary nebula, the...
  • Astronomy Picture of the Day -- Collapse in Hebes Chasma on Mars

    08/11/2014 11:20:40 PM PDT · by SunkenCiv · 19 replies
    NASA ^ | August 12, 2014 | (see photo credit)
    Explanation: What's happened in Hebes Chasma on Mars? Hebes Chasma is a depression just north of the enormous Valles Marineris canyon. Since the depression is unconnected to other surface features, it is unclear where the internal material went. Inside Hebes Chasma is Hebes Mensa, a 5 kilometer high mesa that appears to have undergone an unusual partial collapse -- a collapse that might be providing clues. The above image, taken by the robotic Mars Express spacecraft currently orbiting Mars, shows great details of the chasm and the unusual horseshoe shaped indentation in the central mesa. Material from the mesa appears...
  • Astronomy Picture of the Day -- Rosetta Approaches Comet Churyumov-Gerasimenko

    08/11/2014 7:28:57 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | August 11, 2014 | (see photo credit)
    Explanation: What does it look like to approach a comet? Early this month humanity received a new rendition as the robotic Rosetta spacecraft went right up to -- and began orbiting -- the nucleus of Comet 67P/Churyumov-Gerasimenko. This approach turned out to be particularly fascinating because the comet nucleus first revealed itself to have an unexpected double structure, and later showed off an unusual and craggily surface. The above 101-frame time-lapse video details the approach of the spacecraft from August 1 through August 6. The icy comet's core is the size of a mountain and rotates every 12.7 hours. Rosetta's...
  • Astronomy Picture of the Day -- A Perseid Below

    08/09/2014 10:33:02 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | August 10, 2014 | (see photo credit)
    Explanation: Denizens of planet Earth typically watch meteor showers by looking up. But this remarkable view, captured on August 13, 2011 by astronaut Ron Garan, caught a Perseid meteor by looking down. From Garan's perspective onboard the International Space Station orbiting at an altitude of about 380 kilometers, the Perseid meteors streak below, swept up dust left from comet Swift-Tuttle heated to incandescence. The glowing comet dust grains are traveling at about 60 kilometers per second through the denser atmosphere around 100 kilometers above Earth's surface. In this case, the foreshortened meteor flash is right of frame center, below the...
  • Astronomy Picture of the Day -- A Luminous Night

    08/09/2014 2:38:00 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | August 09, 2014 | (see photo credit)
    Explanation: What shines in the world at night? Just visible to the eye, a rare electric blue glow spread along the shores of Victoria Lake on January 16, 2013. Against reflections of a light near the horizon, this digitally stacked long exposure recorded the bioluminescence of noctiluca scintillans, plankton stimulated by the lapping waves. Above, the night skies of the Gippsland Lakes region, Victoria, Australia shine with a fainter greenish airglow. Oxygen atoms in the upper atmosphere, initially excited by ultraviolet sunlight, produce the more widely seen fading atmospheric chemiluminescence. Washed out by the Earth's rotation, the faint band of...
  • Astronomy Picture of the Day -- Spiral Galaxy NGC 6744

    08/09/2014 2:35:15 PM PDT · by SunkenCiv · 2 replies
    NASA ^ | August 08, 2014 | (see photo credit)
    Explanation: Big, beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo. We see the disk of the nearby island universe tilted towards our line of sight. Orientation and composition give a strong sense of depth to this colorful galaxy portrait that covers an area about the angular size of the full moon. This giant galaxy's yellowish core is dominated by the light from old, cool stars. Beyond the core, spiral arms filled with young blue star clusters and pinkish star forming...
  • Astronomy Picture of the Day -- Rosetta's Rendezvous

    08/09/2014 2:32:21 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | August 07, 2014 | (see photo credit)
    Explanation: On August 3rd, the Rosetta spacecraft's narrow angle camera captured this stunning image of the nucleus of Comet 67P/Churyumov-Gerasimenko. After 10 years and 6.5 billion kilometers of travel along gravity assist trajectories looping through interplanetary space, Rosetta had approached to within 285 kilometers of its target. The curious double-lobed shape of the nucleus is revealed in amazing detail at an image resolution of 5.3 meters per pixel. About 4 kilometers across, the comet nucleus is presently just over 400 million kilometers from Earth, between the orbits of Jupiter and Mars. Now the first spacecraft to achieve a delicate orbit...
  • Astronomy Picture of the Day -- Saturn's Swirling Cloudscape

    08/09/2014 2:29:27 PM PDT · by SunkenCiv · 6 replies
    NASA ^ | August 06, 2014 | (see photo credit)
    Explanation: Acquiring its first sunlit views of far northern Saturn in late 2012, the Cassini spacecraft's wide-angle camera recorded this stunning, false-color image of the ringed planet's north pole. The composite of near-infrared image data results in red hues for low clouds and green for high ones, giving the Saturnian cloudscape a vivid appearance. Enormous by terrestrial standards, Saturn's north polar hurricane-like storm is deep, red, and about 2,000 kilometers wide. Clouds at its outer edge travel at over 500 kilometers per hour. Other atmospheric vortices also swirl inside the large, yellowish green, six-sided jet stream known as the hexagon....
  • Astronomy Picture of the Day -- Four Billion BCE: Battered Earth

    08/09/2014 2:26:38 PM PDT · by SunkenCiv · 20 replies
    NASA ^ | August 05, 2014 | (see photo credit)
    Explanation: No place on Earth was safe. Four billion years ago, during the Hadean eon, our Solar System was a dangerous shooting gallery of large and dangerous rocks and ice chunks. Recent examination of lunar and Earth bombardment data indicate that the entire surface of the Earth underwent piecemeal upheavals, hiding our globe's ancient geologic history, and creating a battered world with no remaining familiar land masses. The rain of devastation made it difficult for any life to survive, although bacteria that could endure high temperatures had the best chance. Oceans thought to have formed during this epoch would boil...
  • Astronomy Picture of the Day -- Shadows and Plumes Across Enceladus

    08/08/2014 4:40:10 PM PDT · by SunkenCiv · 9 replies
    NASA ^ | August 04, 2014 | (see photo credit)
    Explanation: Why does Enceladus have ice plumes? The discovery of jets spewing water vapor and ice was detected by the Saturn-orbiting Cassini spacecraft in 2005. The origin of the water feeding the jets, however, remained a topic of research. A leading hypothesis held that the source might originate from a deep underground sea, but another hypothesis indicated that it might just be ice melted off walls of deep rifts by the moon's tidal flexing and heating. Pictured above, the textured surface of Enceladus is visible in the foreground, while rows of plumes rise from ice fractures in the distance. These...
  • Astronomy Picture of the Day -- Dark Shuttle Approaching

    08/03/2014 9:08:12 AM PDT · by SunkenCiv · 12 replies
    NASA ^ | August 03, 2014 | (see photo credit)
    Explanation: What's that approaching? Astronauts on board the International Space Station first saw it in early 2010 far in the distance. Soon it enlarged to become a dark silhouette. As it came even closer, the silhouette appeared to be a spaceship. Finally, the object revealed itself to be the Space Shuttle Endeavour, and it soon docked as expected with the Earth-orbiting space station. Pictured above, Endeavour was imaged near Earth's horizon as it approached, where several layers of the Earth's atmosphere were visible. Directly behind the shuttle is the mesosphere, which appears blue. The atmospheric layer that appears white is...
  • Astronomy Picture of the Day -- NGC 7023: The Iris Nebula

    08/01/2014 10:40:14 PM PDT · by SunkenCiv · 7 replies
    NASA ^ | August 02, 2014 | (see photo credit)
    Explanation: These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula, NGC 7023 is not the only nebula in the sky to evoke the imagery of flowers, though. Still, this deep telescopic view shows off the Iris Nebula's range of colors and symmetries in impressive detail. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the dusty clouds glow with a faint reddish...
  • Astronomy Picture of the Day -- Tetons and Snake River, Planet Earth

    07/31/2014 10:57:05 PM PDT · by SunkenCiv · 11 replies
    NASA ^ | August 01, 2014 | (see photo credit)
    Explanation: An alluring night skyscape, this scene looks west across the Grand Teton National Park, Wyoming, USA, Planet Earth. The Snake River glides through the foreground, while above the Tetons' rugged mountain peaks the starry sky is laced with exceptionally strong red and green airglow. That night, the luminous atmospheric glow was just faintly visible to the eye, its color and wavey structure captured only by a sensitive digital camera. In fact, this contemporary digital photograph matches the location and perspective of a well-known photograph from 1942 - The Tetons and The Snake River , by Ansel Adams, renown photographer...
  • Astronomy Picture of the Day -- Veins of Heaven

    07/31/2014 10:53:41 PM PDT · by SunkenCiv · 4 replies
    NASA ^ | July 31, 2014 | (see photo credit)
    Explanation: Transfusing sunlight through a still dark sky, this exceptional display of noctilucent clouds was captured earlier this month above the island of Gotland, Sweden. From the edge of space, about 80 kilometers above Earth's surface, the icy clouds reflect sunlight even though the Sun itself is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months the night shining clouds made a strong showing this July. Also known as polar mesopheric clouds they are understood to form as water vapor driven into the cold upper atmosphere condenses on the fine dust particles supplied...
  • Astronomy Picture of the Day -- M31: The Andromeda Galaxy

    07/31/2014 10:49:52 PM PDT · by SunkenCiv · 7 replies
    NASA ^ | July 30, 2014 | (see photo credit)
    Explanation: Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are well in front of the background object. Andromeda is frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about two...
  • Astronomy Picture of the Day -- A Sky Portal in New Zealand

    07/31/2014 10:44:57 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | July 29, 2014 | (see photo credit)
    Explanation: To some, it may look like a portal into the distant universe. To others, it may appear as the eye of a giant. Given poetic license, both are correct. Pictured above is a standard fisheye view of the sky -- but with an unusual projection. The view is from a perch in New Zealand called Te Mata Peak, a name that translates from the Maori language as "Sleeping Giant". The wondrous panorama shows the band of our Milky Way Galaxy right down the center of the sky, with the Large and Small Magellanic Clouds visible to the right. The...
  • Astronomy Picture of the Day -- The Horsehead Nebula from Blue to Infrared

    07/31/2014 10:39:56 PM PDT · by SunkenCiv · 5 replies
    NASA ^ | July 28, 2014 | (see photo credit)
    Explanation: One of the most identifiable nebulae in the sky, the Horsehead Nebula in Orion, is part of a large, dark, molecular cloud. Also known as Barnard 33, the unusual shape was first discovered on a photographic plate in the late 1800s. The red glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick dust, although the lower part of the Horsehead's neck casts a shadow to the left. Streams of gas leaving the nebula are funneled by a strong magnetic field. Bright...