科普 神奇的宇宙----图片(每天更新中)

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Europa Rising

Explanation: When passing Jupiter on your way to Pluto, what should you look for? NASA pondered just this question recently, and the response from one space enthusiast was to capture the above breathtaking moonrise. The unusual vista was then actually captured by the New Horizons spacecraft in February just after it buzzed past Jupiter on its way to Pluto and the outer Solar System. Visible above is the cracked surface of Europa's expansive ice fields, visible just behind a jumble of Jupiter's swirling clouds. Europa is one of the largest moons of Jupiter and a possible host to sub-surface liquid oceans that are real candidates for containing extra-terrestrial life. During the Jupiter flyby, New Horizons also carried out scientific observations of Jupiter's cloud tops and comparative images of Io's volcanoes and its continually changing surface.

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Star Cluster R136 Bursts Out

Explanation: In the center of star-forming region 30 Doradus lies a huge cluster of the largest, hottest, most massive stars known. These stars, known as the star cluster R136, and part of the surrounding nebula are captured here in this gorgeous visible-light image from the Hubble Space Telescope. Gas and dust clouds in 30 Doradus, also known as the Tarantula Nebula, have been sculpted into elongated shapes by powerful winds and ultraviolet radiation from these hot cluster stars. The 30 Doradus Nebula lies within a neighboring galaxy, the Large Magellanic Cloud, located a mere 170,000 light-years away.

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Sombrero Galaxy Across the Spectrum

Explanation: Appropriately famous for its broad ring of obscuring dust and hat-like appearance, the Sombrero Galaxy (aka spiral galaxy M104) is featured in this unique composite view that spans the electromagnetic spectrum, from three major space-based observatories. Exploring the Sombrero's high-energy x-ray emission (blue), the Chandra contribution highlights the pervasive, tenuous, hot gas that extends some 60,000 light-years from the galaxy's center. Hubble's optical view (green) shows the more familiar emission from the Sombrero's population of stars, seen from a nearly edge-on perspective and noticeably bulging at the galaxy's bright core. The broad ring of dust that blocks light in other bands, glows in the infrared contribution (red) from the Spitzer Space Telescope. The Sombrero Galaxy is about 28 million light-years away, near the southern edge of the extensive Virgo cluster of galaxies.

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The Iron Tail of Comet McNaught

Explanation: Outstanding in planet Earth's sky early this year, Comet McNaught is captured in this view from the STEREO A spacecraft. McNaught's coma is so bright, it blooms into the long horizontal stripe at the bottom of the field. Brilliant Venus, near the top left corner, also produces a severe horizontal blemish in the digital image. But the sensitive camera does accurately record the striations in McNaught's famous dust tail along a region stretching over 30 million kilometers toward the top right of the field of view. A separate, fainter, arching tail just to the left of the dust tail was initially thought to be an example of a common ion tail, formed by electrically charged atoms carried away from the comet by the solar wind. However, detailed modeling indicates that tail is actually due to neutral iron atoms pushed out by the pressure of sunlight -- the first ever detected neutral iron tail from a comet. The iron atoms are thought to originate in dust grains from the comet nucleus that contain the iron-sulfur mineral troilite (FeS).

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Small Galaxy NGC 4449

Explanation: Grand spiral galaxies often seem to get all the glory. Their newly formed, bright, blue star clusters along beautiful, symmetric spiral arms are guaranteed to attract attention. But small irregular galaxies form stars too, like NGC 4449, located about 12 million light-years away. The well-studied galaxy is similar in size, and often compared to our Milky Way's satellite galaxy, the Large Magellanic Cloud (LMC). This lovely color image shows NGC 4449's general bar shape, also characteristic of the LMC, with scattered young blue star clusters. Near the bottom is the pinkish glow of atomic hydrogen gas, the telltale tracer of massive star forming regions. NGC 4449 is a member of a group of galaxies found in the constellation Canes Venatici. In fact, interactions with nearby galaxies are thought to have influenced star formation in NGC 4449.

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Sunrise from the Surface of Gliese 581c

Explanation: How might a sunrise appear on Gliese 581c? One artistic guess is shown above. Gliese 581c is the most Earth-like planet yet discovered and lies a mere 20 light-years distant. The central red dwarf is small and redder than our Sun but one of the orbiting planets has recently been discovered to be in the habitable zone where liquid water could exist on its surface. Although this planet is much different from Earth, orbiting much closer than Mercury and containing five times the mass of Earth, it is now a candidate to hold not only oceans but life enabled by the oceans. Were future observations to confirm liquid water, Gliese 581c might become a worthy destination or way station for future interstellar travelers from Earth. Drawn above in the hypothetical, the red dwarf star Gliese 581 rises through clouds above a calm ocean of its planet Gliese 581c.

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A Spider Shaped Crater on Mercury

Explanation: Why does this crater on Mercury look like a spider? When the robotic MESSENGER spacecraft glided by the planet Mercury last month, it was able to image portions of the Sun's closest planet that had never been seen before. When imaging the center of Mercury's extremely large Caloris Basin, MESSENGER found a crater, pictured above, with a set of unusual rays emanating out from its center. A crater with such troughs has never been seen before anywhere in our Solar System. What isn't clear is the relation of the crater to the radial troughs. Perhaps the crater created the radial rays, or perhaps the two features appear only by a chance superposition -- the topic is sure to be one of future research. MESSENGER is scheduled to fly past Mercury twice more before firing its thrusters to enter orbit in 2011.

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Swirling Clouds Over the South Pole of Venus

Explanation: What's happening over the South Pole of Venus? To find out, scientists sent the robot Venus Express spacecraft now orbiting Venus directly over the lower spin axis of Earth's overheated twin. Venus Express confirmed there a spectacular massive swirling storm system with similarities to the vortex recently imaged over Saturn's South Pole. The above composite image in infrared light features Venus' daytime side on the left, shining primarily by reflected sunlight, and nighttime side on the right, shining primarily by thermal light. A Venusian polar vortex is visible as the small circular feature near the center of the thermal infrared image pictured on the right. Close inspection of other South Pole images unexpectedly showed a second vortex, meaning that the unusual swirling clouds are like an Earth-hurricane that has two eyes. Why a double vortex has formed is now a topic of research. The above image was taken last year, and more recent images from Venus Express are being processed that have as much as 100 times more detail.

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Dust Pillar of the Carina Nebula

Explanation: Inside the head of this interstellar monster is a star that is slowly destroying it. The monster, actually an inanimate pillar of gas and dust, measures over a light year in length. The star, not itself visible through the opaque dust, is bursting out partly by ejecting energetic beams of particles. Similar epic battles are being waged all over the star-forming Carina Nebula. The stars will win in the end, destroying their pillars of creation over the next 100,000 years, and resulting in a new open cluster of stars. The pink dots are newly formed stars that have already been freed from their birth monster. The above image is only a small part of a highly detailed panoramic mosaic of the Carina Nebula taken by the Hubble Space Telescope and released last week. The technical name for the stellar jets are Herbig-Haro objects. How a star creates Herbig-Haro jets is an ongoing topic of research, but it likely involves an accretion disk swirling around a central star. A second impressive Herbig-Haro jet is visible across the bottom of a larger image.

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NGC 6302: Big, Bright, Bug Nebula

Explanation: The bright clusters and nebulae of planet Earth's night sky are often named for flowers or insects, and NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the central star of this particular planetary nebula is exceptionally hot though -- shining brightly in ultraviolet light but hidden from direct view by a dense torus of dust. Above is a dramatically detailed close-up of the dying star's nebula recorded by the Hubble Space Telescope. Cutting across a bright cavity of ionized gas, the dust torus surrounding the central star is in the upper right corner of this view, nearly edge-on to the line-of-sight. Molecular hydrogen has recently been detected in this hot star's dusty cosmic shroud. NGC 6302 lies about 4,000 light-years away in the arachnologically correct constellation Scorpius.

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Young Moon and Sister Stars

Explanation: A young crescent Moon shared the western sky with thin clouds and the sister stars of the Pleiades cluster in this early evening skyscape recorded on April 19th. Astronomical images of the well-known Pleiades often show the star cluster's alluring blue reflection nebulae, but they are washed-out here in the clouds and bright moonlight. While the 3-day old Moon is overexposed, surface features can be seen on the dim lunar night side, illuminated by earthshine - light from sunlit planet Earth. Only a week earlier, brilliant Venus also posed near the sister stars. Of course, Venus has not yet wandered too far from the Pleiades and still rules western skies as the evening star.

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M81 in Ursa Major

Explanation: One of the brightest galaxies in planet Earth's sky and similar in size to the Milky Way, big, beautiful spiral M81 lies 11.8 million light-years away in the northern constellation Ursa Major. This remarkably deep image of the region reveals details in the bright yellow core, but at the same time follows fainter features along the galaxy's gorgeous blue spiral arms and sweeping dust lanes. Above M81 lies a dwarf companion galaxy, Holmberg IX, sporting a large, pinkish star-forming region near the top. While M81 and Holmberg IX are seen through a foreground of stars in our own Milky Way galaxy, they are also seen here through a much fainter complex of dust clouds. The relatively unexplored clouds are likely only some hundreds of light-years distant and lie high above our galaxy's plane. Scattered through the image, especially at the the right, the dust clouds reflect the combined light of the Milky Way's stars and have been dubbed integrated flux nebulae.

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Gliese 581 and the Habitable Zone

Explanation: The unremarkable star centered in this skyview is Gliese 581, a mere 20 light-years away toward the constellation Libra. But astronomers are now reporting the discovery of a remarkable system of three planets orbiting Gliese 581, including the most earth-like planet found beyond our solar system. Gliese 581 itself is not a sun-like star, though. Classified as a red dwarf, the star is much smaller and colder than the Sun. Still, the smallest planet known to orbit the star is estimated to be five times as massive as Earth with about 1.5 times Earth's diameter. That super-earth orbits once every 13 days, about 14 times closer to its parent star than the Earth-Sun distance. The close-in orbit around the cool star implies a mean surface temperature of between 0 and 40 degrees C - a range over which water would be liquid - and places the planet in the red dwarf's habitable zone.

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Carina Nebula Panorama from Hubble

Explanation: 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 nebula. 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. The Keyhole Nebula, visible left the center, houses several of the most massive stars known and has also 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. Pictured above is the most detailed image of the Carina Nebula ever taken. The controlled color image is a composite of 48 high-resolution frames taken by the Hubble Space Telescope and released to honor its 17th anniversary. Wide-field annotated and zoomable image versions are also available.

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The Sun in Three Dimensions

Explanation: What does the Sun look like in all three spatial dimensions? To find out, NASA launched two STEREO satellites to perceive three dimensions on the Sun much like two eyes allow humans to perceive three dimensions on the Earth. Such a perspective is designed to allow new insight into the surface of the rapidly changing Sun, allowing humans to better understand and predict things like Coronal Mass Ejections and solar flares that affect the Earth as well as satellites and astronauts orbiting the Earth. Pictured above are two simultaneous images of the Sun taken by STEREO A and STEREO B, now digitally combined to give one of the first 3-D pictures of the Sun ever taken. To fully appreciate the image, one should view it with 3-D red-blue glasses. The teeming and bubbling solar surface can be seen sporting a prominent solar prominence near the top of the image.

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A Supply Ship Approaches the Space Station

Explanation: Looking out a window of the International Space Station brings breathtaking views. Visible vistas include a vast and colorful Earth, a deep dark sky, and an occasional spaceship sent to visit the station. Visible on September 20 of last year was a Soyuz TMA-9 spacecraft carrying not only supplies but also three new astronauts. A few days before this picture was taken, the U.S. Space Shuttle Atlantis had just departed. The three new approaching astronauts were American Michael E. Lopez-Alegria, Russian Mikhail Tyurin, and Iranian-American Anousheh Ansari. Ms. Ansari visited the International Space Station (ISS) briefly as a paying spaceflight participant for the Federal Space Agency of Russia, and wrote a popular blog about her experiences. Lopez-Alegria would lead the ISS crew dubbed Expedition 14, which included the flight engineer and Soyuz pilot Tyurin, flight engineer American Sunita Williams, and flight engineer German Thomas Reiter. Tyurin returned to the Earth with Lopez-Alegria this past week.

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Smooth Sections of Asteroid Itokawa

Explanation: Why are parts of this asteroid's surface so smooth? No one is yet sure, but it may have to do with the dynamics of an asteroid that is a loose pile of rubble rather than a solid rock. The unusual asteroid has been visited recently by the Japanese spacecraft Hayabusa that has been documenting its unusual structure and mysterious lack of craters. Recent analyses of the border regions between smooth and rugged sections of Itokawa indicate that jostling of the asteroid might be creating segregation between large and small rocks near the surface, like the Brazil nut effect. In late 2005, Hayabusa actually touched down on one of the smooth patches, dubbed the MUSES Sea, and collected soil samples that are to be returned to Earth for analysis. Hayabusa will start its three-year long return trip to Earth this month. Computer simulations show that 500-meter asteroid Itokawa may impact the Earth within the next few million years.

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3D Face on Mars

Explanation: Get out your red/blue glasses and gaze down on this weathered mesa on Mars. Of course, described as a rock formation that resembles a human head in a 1976 NASA press release, this mesa is also famous as the Face on Mars. The sharp stereo image was created by combining high resolution pictures from cameras on two different spacecraft in Mars orbit - Mars Reconnaissance Orbiter and Mars Global surveyor. It shows rugged details of the approximately 2 kilometer wide, isolated hill - similar to mesa landforms on planet Earth - rising some 240 meters above the plains of the martian Cydonia region. This remarkable 3D view exaggerates the hill's vertical dimensions.

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Pantheon Earth and Moon

Explanation: Could this be a picture of the Earth and Moon from space? It certainly looks like it at first glance, with a cratered Moon standing off from planet Earth's lovely blue disk surrounded by a nurturing atmosphere. In fact, this view looks up into the dome of the ancient Pantheon in Rome. The Earth's blue disk is really the daytime sky with clouds seen through a nine meter diameter central opening in the dome. The circular opening, or oculus, was intended as the source of light for the building's interior. The Moon is actually direct sunlight streaming through the oculus onto the dome's inner ribbed structure. Historian Soeren Dalsgaard snapped the evocative picture in February and comments that for almost two thousand years the rays of the Sun have traced a steady path on the inside of the Pantheon's cupola. A testament to Roman architecture and engineering, the Pantheon's dome is said to symbolize the vault of the heavens.

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NGC 5139: Omega Centauri

Explanation: Centaurus is one of the most striking constellations in the southern sky. The Milky Way flows through this celestial expanse whose wonders also include the closest star system to the Sun, Alpha Centauri, and the largest globular star cluster in our galaxy, Omega Centauri (aka NGC 5139). This sharp telescopic view of Omega Centauri shows off the central regions of the cluster of about 10 million stars. Omega Cen itself is about 15,000 light-years away and 150 light-years in diameter - the largest of 150 or so known globular star clusters that roam the halo of our galaxy. Though most star clusters consist of stars with the same age and composition, the enigmatic Omega Cen exhibits the presence of different stellar populations with a spread of ages and chemical abundances. In fact, Omega Cen may be the remnant core of a small galaxy merging with the Milky Way.