Astronomic Picture of Day

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elraro #31 Mar '16

Dark Sun over Ternate

A dark Sun hangs in the clearing sky over a volcanic planet in this morning sea and skycape. It was taken during this week's total solar eclipse, a dramatic snapshot from along the narrow path of totality in the dark shadow of a New Moon. Earth's Indonesian isle of Ternate, North Maluku lies in the foreground. The sky is still bright near the eastern horizon though, beyond the region's flattened volcanic peaks and outside the Moon's umbral shadow. In fact, near the equator the dark lunar umbra is rushing eastward across Earth's surface at about 1,700 kilometers (1,100 miles) per hour. Shining through the thin clouds, around the Sun's silhouette is the alluring glow of the solar corona, only easily seen during totality. An inspiring sight for eclipse watchers, this solar corona is the tenuous, hot outer atmosphere of the Sun.

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elraro #32 Mar '16

Lunar Shadow Transit

This snapshot from deep space captures planet Earth on March 9. The shadow of its large moon is falling on the planet's sunlit hemisphere. Tracking toward the east (left to right) across the ocean-covered world the moon shadow moved quickly in the direction of the planet's rotation. Of course, denizens of Earth located close to the shadow track centerline saw this lunar shadow transit as a brief, total eclipse of the Sun. From a spacebased perspective between Earth and Sun, the view of this shadow transit was provided by the Deep Space Climate Observatory (DSCOVR) spacecraft's Earth Polychromatic Imaging Camera (EPIC).

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elraro #33 Mar '16

The Flash Spectrum of the Sun

In a flash, the visible spectrum of the Sun changed from absorption to emission on March 9 during the total solar eclipse. That fleeting moment, at the beginning the total eclipse phase, is captured by telephoto lens and diffraction grating in this image from clearing skies over Ternate, Indonesia. At left, the overwhelming light from the Sun is just blocked by the lunar disk. The normally dominant absorption spectrum of the solar photosphere is hidden. What remains, spread by the diffraction grating into the spectrum of colors to the right of the eclipsed Sun, are individual eclipse images. The images appear at each wavelength of light emitted by atoms along the thin visible arc of the solar chromosphere and in an enormous prominence extending beyond the Sun's upper limb. The brightest images, or strongest chromospheric emission lines, are due to Hydrogen atoms that produce the red hydrogen alpha emission at the far right and blue hydrogen beta emission to the left. In between, the bright yellow emission image is caused by atoms of Helium, an element only first discovered in the flash spectrum of the Sun.

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elraro #34 Mar '16

Neon Saturn

If seen in the right light, Saturn glows like a neon sign. Although Saturn has comparatively little of the element neon, a composite image false-colored in three bands of infrared light highlights features of the giant ringed planet like a glowing sign. At the most blue band of the infrared light featured, false-colored blue in the above image, Saturn itself appears dark but Saturn's thin rings brightly reflect light from our Sun. Conversely, Saturn's B ring is so thick that little reflected light makes it through, creating a dark band between Saturn's A and C rings. At the most red band of the infrared, false-colored red above, Saturn emits a surprisingly detailed thermal glow, indicating planet-wide bands, huge hurricane-like storms, and a strange hexagon-shaped cloud system around the North Pole. In the middle infrared band, false-colored green, the sunlit side of Saturn's atmosphere reflects brightly. The above image was obtained in 2007 by the robotic Cassini spacecraft orbiting about 1.6 million kilometers out from Saturn. Follow APOD on: Facebook, Google Plus, Twitter, or Instagram

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elraro #35 Mar '16

Dark Nebulas across Taurus

Sometimes even the dark dust of interstellar space has a serene beauty. One such place occurs toward the constellation of Taurus. The filaments featured here can be found on the sky between the Pleiades star cluster and the California Nebula. This dust is not known not for its bright glow but for its absorption and opaqueness. Several bright stars are visible with their blue light seen reflecting off the brown dust. Other stars appear unusually red as their light barely peaks through a column of dark dust, with red the color that remains after the blue is scattered away. Yet other stars are behind dust pillars so thick they are not visible here. Although appearing serene, the scene is actually an ongoing loop of tumult and rebirth. This is because massive enough knots of gas and dust will gravitationally collapse to form new stars -- stars that both create new dust in their atmospheres and destroy old dust with their energetic light and winds.

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elraro #36 Mar '16

Cheering a Total Solar Eclipse

What would you do if you saw the Sun disappear? Quite possibly: cheer. That's what many exuberant sky watchers did across Indonesia during a total eclipse of the Sun last week. There and then, the land and sky went dark during the day as our Sun disappeared for a few minutes behind our Moon. Many people watching knew they were witnessing a rare event, and their joyous exclamations can be heard on the featured video. What a far cry this reaction is from centuries ago, when more typical eclipse reactions derived from fear and worry. The video shows first shows a Sun only partly eclipsed by the Moon as totality approached. From many locations, foreground clouds on our Earth either obscured the view or made the view more interesting. The total eclipse was only visible from a narrow swath of Earth that included several Indonesian islands. At the same time, in the opposite direction, NASA's EPIC camera aboard NOAA's DSCOVR satellite captured the shadow of the Moon moving across the Earth. APOD is also available in: Arabic, Bahasa Indonesian, Catalan, Chinese, Chinese, Croatian, Czech, Dutch, Farsi, Farsi, Galego, German, French, Hebrew, Japanese, Korean, Montenegrin, Polish, Romanian, Russian, Serbian, Slovenian, Spanish, and Turkish

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elraro #37 Mar '16

A Phoenix Aurora over Iceland

All of the other aurora watchers had gone home. By 3:30 am in Iceland, on a quiet night last September, much of that night's auroras had died down. Suddenly though, a new burst of particles streamed down from space, lighting up the Earth's atmosphere once again. This time, unexpectedly, pareidoliacally, they created an amazing shape reminiscent of a giant phoenix. With camera equipment at the ready, two quick sky images were taken, followed immediately by a third of the land. The mountain in the background is Helgafell, while the small foreground river is called Kaldá, both located about 30 kilometers north of Iceland's capital Reykjavik. Seasoned skywatchers will note that just above the mountain, toward the left, is the constellation of Orion, while the Pleiades star cluster is also visible just above the frame center. The new aurora lasted only a minute and would be gone forever -- possibly dismissed as an embellished aberration -- were it not captured in the featured, digitally-composed, image mosaic.

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Sonos #38 Mar '16 MV Wizard

Con las constelaciones que mola mucho

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[Borrado] #39 Mar '16

Impresionante.

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elraro #40 Mar '16

Close Comet and Large Magellanic Cloud

Sporting a surprisingly bright, lovely green coma Comet 252P/Linear poses next to the Large Magellanic Cloud in this southern skyscape. The stack of telephoto exposures was captured on March 16 from Penwortham, South Australia. Recognized as a Jupiter family periodic comet, 252P/Linear will come close to our fair planet on March 21, passing a mere 5.3 million kilometers away. That's about 14 times the Earth-Moon distance. In fact, it is one of two comets that will make remarkably close approaches in the next few days as a much fainter Comet Pan-STARRS (P/2016 BA14) comes within 3.5 million kilometers (9 times the Earth-Moon distance) on March 22. The two have extremely similar orbits, suggesting they may have originally been part of the same comet. Sweeping quickly across the sky because of their proximity to Earth, both comets will soon move into northern skies.

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elraro #41 Mar '16

The W in Cassiopeia

A familiar, zigzag, W pattern in northern constellation Cassiopeia is traced by five bright stars in this colorful and broad mosaic. Stretching about 15 degrees across rich starfields, the celestial scene includes dark clouds, bright nebulae, and star clusters along the Milky Way. In yellow-orange hues Cassiopeia's alpha star Shedar is a standout though. The yellowish giant star is cooler than the Sun, over 40 times the solar diameter, and so luminous it shines brightly in Earth's night from 230 light-years away. A massive, rapidly rotating star at the center of the W, bright Gamma Cas is about 550 light-years distant. Bluish Gamma Cas is much hotter than the Sun. Its intense, invisible ultraviolet radiation ionizes hydrogen atoms in nearby interstellar clouds to produce visible red H-alpha emission as the atoms recombine with electrons. Of course, night skygazers in the Alpha Centauri star system would also see the recognizable outline traced by Cassiopeia's bright stars. But from their perspective a mere 4.3 light-years away they would see our Sun as a sixth bright star in Cassiopeia, extending the zigzag pattern just beyond the left edge of this frame.

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Dieter #42 Mar '16 Penitente

cuidado con el general tiñoso

D4rKNiGhT #43 Mar '16

Que se supone que es esto?

Salcort #44 Mar '16

Estoy por salirme del grupo, todo lo que se publica ultimamente son "copy&paste" en ingles.

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elraro #45 Mar '16

#44 es que el apod se publica en inglés. Nunca he visto a la NASA publicar nada en español. Es un bot que descarga de la api y pega. Arriba hay una web que traduce el apod, y tengo pendiente a ver si puedo extraer esa info y pasarla aquí.

Mientras tanto, si quieres, puedes echar un cable y pegar la traducción ^^

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ruonory #46 Mar '16

#45 Creo que lo que quiere decir es que no hace falta anunciar en el grupo de ciencia estas cosas, quien quiera verlas, que ponga este hilo en favoritos.

Conste que yo no me quejo porque me gusta, pero puedo entenderlo.

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elraro #47 Mar '16

#46 ok, en ese caso sin problema. mañana desactivo el aviso de grupo

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elraro #48 Mar '16

3D Ahuna Mons

Get out your red/blue glasses and gaze across Ceres at mysterious mountain Ahuna Mons. Shown in a 3D anaglyph perspective view, the mosaicked image data was captured in December of 2015, taken from the Dawn spacecraft's low-altitude mapping orbit about 385 kilometers above the surface of the dwarf planet. A remarkable dome-shaped feature on Ceres, with steep, smooth sides Ahuna Mons is about 20 kilometers (12 miles) in diameter at its base, rising on average 4 kilometers to a flattened summit. Similar in size to mountains found on planet Earth, no other Cerean surface feature is so tall and well-defined. It is not known what process shaped the lonely Ahuna Mons, or if the bright material streaking its steepest side is the same material responsible for Ceres' famous bright spots.

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elraro #49 Mar '16

A Picturesque Equinox Sunset

What's that at the end of the road? The Sun. Many towns have roads that run east - west, and on two days each year, the Sun rises and sets right down the middle. Today is one of those days: an equinox. Not only is today a day of equal night (("aequus"-"nox") and day time, but also a day when the sun rises precisely to the east and sets due west. Featured here is a picturesque road in northwest Illinois, USA that runs approximately east -west. The image was taken one year ago today, during the March Equinox of 2015, and shows the Sun down the road at sunset. In many cultures, this March equinox is taken to be the first day of a season, typically spring in Earth's northern hemisphere, and autumn in the south. Does your favorite street run east - west? Tonight at sunset, with a quick glance, you can actually find out. Quiz (really hard): What road is pictured?

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ruonory #50 Mar '16

#49 Super inteligente, luego vas conduciendo en el ocaso y el solazo metiéndote en la cara, que es cantidad de peligroso.

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intelntl #51 Mar '16

#50 Teniendo en cuenta que pasa dos veces al año yo no me preocuparía.

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ruonory #52 Mar '16

#51 Joder, pasa dos veces por ahí, pero el resto del tiempo no anda muy alejado de ese ángulo.

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elraro #53 Mar '16

Alaskan Moondogs

What's happened to the sky? Moonlight illuminates a snowy scene in this night land and skyscape made on 2013 January from Lower Miller Creek, Alaska, USA. Overexposed near the mountainous western horizon is the first quarter Moon itself, surrounded by an icy halo and flanked left and right by moondogs. Sometimes called mock moons, a more scientific name for the luminous apparitions is paraselenae (plural). Analogous to a sundog or parhelion, a paraselene is produced by moonlight refracted through thin, hexagonal, plate-shaped ice crystals in high cirrus clouds. As determined by the crystal geometry, paraselenae are seen at an angle of 22 degrees or more from the Moon. Compared to the bright lunar disk, paraselenae are faint and easier to spot when the Moon is low. Follow APOD on: Facebook, Google Plus, Instagram, or Twitter

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elraro #54 Mar '16

Rainbow Airglow over the Azores

Why would the sky glow like a giant repeating rainbow? Airglow. Now air glows all of the time, but it is usually hard to see. A disturbance however -- like an approaching storm -- may cause noticeable rippling in the Earth's atmosphere. These gravity waves are oscillations in air analogous to those created when a rock is thrown in calm water. The long-duration exposure nearly along the vertical walls of airglow likely made the undulating structure particularly visible. OK, but where do the colors originate? The deep red glow likely originates from OH molecules about 87-kilometers high, excited by ultraviolet light from the Sun. The orange and green airglow is likely caused by sodium and oxygen atoms slightly higher up. The featured image was captured during a climb up Mount Pico in the Azores of Portugal. Ground lights originate from the island of Faial in the Atlantic Ocean. A spectacular sky is visible through this banded airglow, with the central band of our Milky Way Galaxy running up the image center, and M31, the Andromeda Galaxy, visible near the top left. Explore Your Universe: Random APOD Generator

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elraro #55 Mar '16

The Great Nebula in Carina

In one of the brightest parts of Milky Way lies a nebula where some of the oddest things occur. NGC 3372, known as the Great Nebula in Carina, is home to massive stars and changing nebulas. The Keyhole Nebula (NGC 3324), the bright structure just above the image center, houses several of these massive stars and has itself changed its appearance. The entire Carina Nebula spans over 300 light years and lies about 7,500 light-years away in the constellation of Carina. Eta Carinae, the most energetic star in the nebula, was one of the brightest stars in the sky in the 1830s, but then faded dramatically. Eta Carinae is the brightest star near the image center, just left of the Keyhole Nebula. While Eta Carinae itself maybe on the verge of a supernova explosion, X-ray images indicate that much of the Great Carina Nebula has been a veritable supernova factory.

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elraro #56 Mar '16

Joder que maravilla de fotos :qq: :qq: :qq: :qq:

Necesito un puto telescopio ya...

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J_Penny #57 Mar '16

#56 yo estoy igual que tu hahaha aunque me gustaría descubrir como usar una relfex y un telescopio, pero algo me dice que se me va de presupuesto el telescopio hahahha

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elraro #58 Mar '16

Hickson 91 in Piscis Austrinus

Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups (HCGs). This sharp telescopic image captures one such galaxy group, HCG 91, in beautiful detail. The group's three colorful spiral galaxies at the center of the field of view are locked in a gravitational tug of war, their interactions producing faint but visible tidal tails over 100,000 light-years long. Their close encounters trigger furious star formation. On a cosmic timescale the result will be a merger into a large single galaxy, a process now understood to be a normal part of the evolution of galaxies, including our own Milky Way. HCG 91 lies about 320 million light-years away in the constellation Piscis Austrinus. But the impressively deep image also catches evidence of fainter tidal tails and galaxy interactions close to 2 billion light-years distant.

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elraro #59 Mar '16

Close Comet and the Milky Way

Comet 252P/Linear's lovely greenish coma is easy to spot in this expansive southern skyscape. Visible to the naked eye from the dark site near Flinders, Victoria, Australia, the comet appears tailless. Still, its surprisingly bright coma spans about 1 degree, posed here below the nebulae, stars, and dark rifts of the Milky Way. The five panels used in the wide-field mosaic were captured after moonset and before morning twilight on March 21. That was less than 24 hours from the comet's closest approach, a mere 5.3 million kilometers from our fair planet. Sweeping quickly across the sky because it is so close to Earth, the comet should be spotted in the coming days by northern hemisphere comet watchers. In predawn but moonlit skies it will move through Sagittarius and Scorpius seen toward the southern horizon. That's near the triangle formed by bright, yellowish, Mars, Saturn, and Antares at the upper left of this frame.

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elraro #60 Mar '16

Solstice to Equinox Cubed

This 3 month long exposure packed the days from December 22, 2015 through March 20 into a box. Dubbed a solargraph, the unconventional, unfolded picture was recorded with a pinhole camera made from a cube-shaped container, its sides lined with photographic paper. Fixed to a single spot for the entire exposure, the simple camera recorded the Sun's path through Hungarian skies. Each day a glowing trail was burned into the photosensitive paper. From short and low, to long and high, the trails follow the progression from winter solstice to spring equinox. Of course, dark gaps in the daily sun trails are caused by cloud cover. Sunny days produce the more continuous bright tracks.

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