科普 神奇的宇宙----图片(每天更新中)

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Maneuvering in Space

Explanation: What arm is 17 meters long and sometimes uses humans for fingers? The Canadarm2 aboard the International Space Station (ISS). Canadarm2 has multiple joints and is capable of maneuvering payloads as massive as 116,000 kilograms, equivalent to a fully loaded bus. Canadarm2 is operated by remote control by a human inside the space station. To help with tasks requiring a particularly high level of precision and detail, an astronaut can be anchored to an attached foot constraint. The arm is able propel itself end-over-end around the outside of the space station. Pictured above, astronaut Stephen Robinson rides Canadarm2 during the STS-114 mission of the space shuttle Discovery to the ISS in 2005 August. Space shuttles often deploy their own original version of a robotic arm dubbed Canadarm. Next year, a second robotic arm is scheduled to be deployed on the space station.

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An Intermediate Polar Binary System

Explanation: How can two stars create such a strange and intricate structure? Most stars are members of multiple-star systems. Some stars are members of close binary systems where material from one star swirls around the other in an accretion disk. Only a handful of stars, however, are members of an intermediate polar, a system featuring a white dwarf star with a magnetic field that significantly pushes out the inner accretion disk, only allowing material to fall down its magnetic poles. Shown above is an artist's depiction of an intermediate polar system, also known as a DQ Hercules system. The foreground white dwarf is so close to the normal star that it strips away its outer atmosphere. As the white dwarf spins, the columns of infalling gas rotate with it. The name intermediate polar derives from observations of emitted light polarized at a level intermediate to non-disk binary systems known as polars. Intermediate polars are a type of cataclysmic variable star system.

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Elliptical Galaxy M87

Explanation: In spiral galaxies, majestic winding arms of young stars and interstellar gas and dust rotate in a flat disk around a bulging galactic nucleus. But elliptical galaxies seem to be simpler. Lacking gas and dust to form new stars, their randomly swarming older stars, give them an ellipsoidal (egg-like) shape. Still, elliptical galaxies can be very large. Over 120,000 light-years in diameter (larger than our own Milky Way), elliptical galaxy M87 is the dominant galaxy at the center of the Virgo Galaxy Cluster, some 50 million light-years away. M87 is likely home to a supermassive black hole responsible for the high-energy jet of particles emerging from the giant galaxy's central region.

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The Gum Nebula

Explanation: Named for Australian astronomer Colin Stanley Gum (1924-1960), The Gum Nebula is so large and close it is actually hard to see. In fact, we are only about 450 light-years from the front edge and 1,500 light-years from the back edge of this cosmic cloud of glowing hydrogen gas. Covered in this 41 degree-wide mosaic of H-alpha images, the faint emission region is otherwise easy to lose against the background of Milky Way stars. The complex nebula is thought to be a supernova remnant over a million years old, sprawling across the southern constellations Vela and Puppis. Sliding your cursor over this spectacular wide field view will reveal the location of objects embedded in The Gum Nebula, including the Vela supernova remnant.

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Shell Game in the LMC

Explanation: An alluring sight in dark southern skies, the Large Magellanic Cloud (LMC) is seen here through a narrow filter that transmits only the red light of hydrogen atoms. Ionized by energetic starlight, a hydrogen atom emits the characteristic red H-alpha light as its single electron is recaptured and transitions to lower energy states. As a result, this image of the LMC seems covered with shell-shaped clouds of hydrogen gas surrounding massive, young stars. Sculpted by the strong stellar winds and ultraviolet radiation, the glowing hydrogen clouds are known as H II (ionized hydrogen) regions. This high resolution mosaic view was recorded in 6 segments, each with 200 minutes of exposure time. Itself composed of many overlapping shells, the Tarantula Nebula, is the large star forming region near top center. A satellite of our Milky Way Galaxy, the LMC is about 15,000 light-years across and lies a mere 180,000 light-years away in the constellation Dorado.

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The Host Galaxies of Long-Duration GRBs

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Explanation: What causes the powerful explosions known as gamma-ray bursts? Astrophysicists still aren't sure, but the longest duration gamma-ray bursts (GRBs) seem to involve very massive stars. A new clue indicating this was uncovered recently by a series of images taken by the orbiting Hubble Space Telescope. These images, shown above, indicate that long duration GRBs typically appear to come from galaxies and regions of galaxies with bright regions rich with star formation and bright, massive stars. Long GRBs are therefore different than many types of supernovas, which occur more uniformly distributed in their host galaxies. Since such active star forming regions are relatively rare in our Milky Way Galaxy, the chances of a nearby GRB affecting life on Earth are relatively slight.

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Volcanic Bumpy Boulder on Mars

Explanation: What created this unusually textured rock on Mars? Most probably: a volcano. Dubbed Bumpy Boulder, the strange stone measuring just under a half-meter high was found by the robotic Spirit rover currently rolling across Mars. Pits on the ragged rock are likely vesicles and arise from hot gas bubbling out of hot rock ejected by an active Martian volcano. Several similar rocks are visible near Bumpy Boulder that likely have a similar past. The above true-color image was taken about one month ago. The Spirit rover, now in its third year of operation on Mars, is weathering the low sunlight winter of Mar's northern hemisphere on a hillside slope in order to maximize the amount of absorbable battery-refreshing sunlight.

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The Very Large Array of Radio Telescopes

Explanation: The most photogenic array of radio telescopes in the world has also been one of the most productive. Each of the 27 radio telescopes in the Very Large Array (VLA) is the size of a house and can be moved on train tracks. The above pictured VLA, inaugurated in 1980 is situated in New Mexico, USA. The VLA has been used to discover water on planet Mercury, radio-bright coronae around ordinary stars, micro-quasars in our Galaxy, gravitationally-induced Einstein rings around distant galaxies, and radio counterparts to cosmologically distant gamma-ray bursts. The vast size of the VLA has allowed astronomers to study the details of super-fast cosmic jets, and even map the center of our Galaxy. An upgrade of the VLA is being planned.

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Crumbling Comet

Explanation: This false-color mosaic of crumbling comet Schwassmann-Wachmann 3 spans about 6 degrees (12 full moons) along the comet's orbit. Recorded on May 4-6 by an infrared camera on board the Spitzer Space Telescope, the picture captures about 45 of the 60 or more alphabetically cataloged large comet fragments. The brightest fragment at the upper right of the track is Fragment C. Bright Fragment B is below and left of center. Looking for clues to how the comet broke up, Spitzer's infrared view also captures the trail of dust left over as the comet deteriorated during previous passes. Emission from the dust particles warmed by sunlight appears to fill the space along the cometary orbit. The fragments are near their closest approach in the coming days, about 10 million kilometers away, and none pose any danger to our fair planet.

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Comet Meets Ring Nebula: Part II

Explanation: Moving rapidly through planet Earth's night sky, Fragment C of crumbling comet 73P/Schwassmann-Wachmann 3 passed almost directly in front of M57 - the Ring Nebula, and faint spiral galaxy IC 1296 on May 8. In fact, in this gorgeous view, the bright head of Fragment C is separated by only about 0.1 degrees from M57, with the tail apparently engulfing nebula and galaxy. Recorded from Elizabeth, Illinois, USA, this picture corresponds to the cosmic scene only 30 minutes after yesterday's picture of the approaching alignment. The relative motion of the comet against the background stars and nebulae is easy to see when comparing the two images. This comet's fragments will be near their closest approach in the coming days, about 10 million kilometers away, and none pose any danger to our fair planet.

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Comet Meets Ring Nebula: Part I

Explanation: As dawn approached on May 8, astronomer Stefan Seip carefully watched Fragment C of broken comet 73P/Schwassmann-Wachmann 3 approach M57 - the Ring Nebula, and faint spiral galaxy IC 1296. Of course, even though the trio seemed to come close together in a truly cosmic photo opportunity, the comet is in the inner part of our solar system, a mere 0.5 light-minutes or so from Seip's telescope located near Stuttgart, Germany, planet Earth. The Ring Nebula (upper right) is more like 2,000 light-years distant, well within our own Milky Way Galaxy. At a distance of 200 million light-years, IC 1296 (between comet and ring) is beyond even the Milky Way's boundaries. Because the comet is so close, it appears to move relatively rapidly against the distant stars. This dramatic telescopic view was composited from two sets of images; one compensating for the comet's apparent motion and one recording the background stars and nebulae.

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The Large Cloud of Magellan

Explanation: Portuguese navigator Fernando de Magellan and his crew had plenty of time to study the southern sky during the first circumnavigation of planet Earth. As a result, two fuzzy cloud-like objects easily visible for southern hemisphere skygazers are known as the Clouds of Magellan. Of course, these star clouds are now understood to be dwarf irregular galaxies, satellites of our larger spiral Milky Way galaxy. The Large Magellanic Cloud (LMC) pictured above is only about 180,000 light-years distant in the constellation Dorado. Spanning about 15,000 light-years or so, it is the most massive of the Milky Way's satellite galaxies and is the site of the closest supernova in modern times. The prominent red knot on the left is 30 Doradus, or the Tarantula Nebula, a giant star-forming region in the Large Magellanic Cloud.

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Descent Panorama of Saturn's Titan

Explanation: You're the first spacecraft ever to descend to Titan -- what do you see? Immediately after the Huygen's probe pierced the cloud deck of Saturn's moon Titan last January, it took a unique series of pictures of one of the Solar System's most mysterious moon's. Those pictures have recently been digitally stitched together to create spectacular panoramas and a dramatic descent movie. Pictured above is a panoramic fisheye view Huygen's obtained from about five kilometers above Titan's surface. The digital projection makes the local surface, mostly flat, appear as a ball, but allows one to see in all directions. Huygen's eventual landing site was in the large dark area below, just right of the center. This relatively featureless, dark, sandy basin appears to be surrounded by light colored hills to the right and a landscape fractured by streambeds and canyons above. Recent evidence indicates that Titan's lakebeds and streambeds are usually dry but sometimes filled with a flashflood of liquid methane from rare torrents of methane rain.

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NGC 2440: Cocoon of a New White Dwarf

Explanation: Like a butterfly, a white dwarf star begins its life by casting off a cocoon that enclosed its former self. In this analogy, however, the Sun would be a caterpillar and the ejected shell of gas would become the prettiest of all! In the above cocoon, the planetary nebula designated NGC 2440, contains one of the hottest white dwarf stars known. The white dwarf can be seen as the bright dot near the photo's center. Our Sun will eventually become a "white dwarf butterfly", but not for another 5 billion years. The above false color image was post-processed by Forrest Hamilton.

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Three Galaxies in Draco

Explanation: This intriguing trio of galaxies is sometimes called the NGC 5985/Draco Group and so (quite reasonably) is located in the northern constellation Draco. From left to right are face-on spiral NGC 5985, elliptical galaxy NGC 5982, and edge-on spiral NGC 5981 -- all within this single telescopic field of view spanning a little more than half the width of the full moon. While this grouping is far too small to be a galaxy cluster and has not been cataloged as a compact group, these galaxies all do lie roughly 100 million light-years from planet Earth. On close examination with spectrographs, the bright core of the striking face-on spiral NGC 5985 shows prominent emission in specific wavelengths of light, prompting astronomers to classify it as a Seyfert, a type of active galaxy. Not as well known as other tight groupings of galaxies, the contrast in visual appearance makes this triplet an attractive subject for astrophotographers. This impressively deep exposure of region also reveals faint and even more distant background galaxies.

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Jupiter and the Red Spots

Explanation: Jupiter's Great Red Spot is a swirling storm seen for over 300 years, since the beginning of telescopic observations. But in February 2006, planetary imager Christopher Go noticed it had been joined by Red Spot Jr - formed as smaller whitish oval-shaped storms merged and then developed the remarkable reddish hue. This sharp Hubble Space Telescope image showing the two salmon-colored Jovian storms was recorded in April. About half the size of the original Red Spot, Red Spot Jr. is similar in diameter to planet Earth. Seen here below and left of the ancient storm system, it trails the Great Red Spot by about an hour as the planet rotates from left to right. While astronomers still don't exactly understand why Jupiter's red spots are red, they do think the appearance of Red Spot Jr. provides evidence for climate change on the Solar System's ruling gas giant.

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Liquid Sea on Saturn's Titan

Explanation: What is this vast dark region on Titan? Quite possible a sea of liquid hydrocarbons. The region was imaged earlier this month when the robotic Cassini spacecraft swooped past Saturn's cloudy moon and illuminated part of it with radar. The dark region in the above image reflected little radar, an effect expected were the dark surface relatively flat, as expected for a liquid. Other indications that the vast dark area is liquid include the coastline-like topology of the brighter regions, which appear to include islands, inlets, and tributary channels. The uninterrupted smoothness of much of the dark sea may indicate that the sea runs deep, with speculation holding a depth estimate of tens of meters. A hydrocarbon sea on Titan holds particular interest for exobiologists as it might be a place where life could develop. In 2005 the Huygens probe landed on Titan and returned the first surface images. Cassini will continue to explore Titan, as 13 more flybys are planned.

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Bright Spiral Galaxy M81 from Hubble

Explanation: The Hubble Space Telescope has resolved individual stars in a spectacular new image of nearby spiral galaxy M81. The feat is similar to Edwin Hubble's historic images with the Mt. Wilson 100-inch Hooker Telescope in the 1920s that resolved stars in neighboring galaxy M31. Edwin Hubble was able to use individual Cepheid variable stars to show that M31 was not nearby swirling gas but rather an entire galaxy like our Milky Way Galaxy. This above image in visible light taken by the Hubble Space Telescope is being used in conjunction with images being taken in ultraviolet by Galex, infrared by Spitzer, and X-rays with Chandra to study how stars have formed and died over the history M81. Light takes about 12 million years to reach us from M81. M81 is visible with binoculars toward the constellation of the Great Bear (Ursa Major).

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A Hole in Mars

Explanation: Black spots have been discovered on Mars that are so dark that nothing inside can be seen. Quite possibly, the spots are entrances to deep underground caves capable of protecting Martian life, were it to exist. The unusual hole pictured above was found on the slopes of the giant Martian volcano Arsia Mons. The above image was captured three weeks ago by the HiRISE instrument onboard the Mars Reconnaissance Orbiter currently circling Mars. The holes were originally identified on lower resolution images from the Mars Odyssey spacecraft, The above hole is about the size of a football field and is so deep that it is completely unilluminated by the Sun. Such holes and underground caves might be prime targets for future spacecraft, robots, and even the next generation of human interplanetary explorers.

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The Horsehead Nebula

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 spots in the Horsehead Nebula's base are young stars just in the process of forming. Light takes about 1500 years to reach us from the Horsehead Nebula. The above image was taken with the 0.9-meter telescope at Kitt Peak National Observatory.