科普 神奇的宇宙----图片(每天更新中)

wsbswdx

The Star Clusters of NGC 1313

Explanation: Like grains of sand on a cosmic beach, individual stars of barred spiral galaxy NGC 1313 are resolved in this sharp composite from the Hubble Space Telescope's Advanced Camera for Surveys (ACS). The inner region of the galaxy is pictured, spanning about 10,000 light-years. Hubble's unique ability to distinguish individual stars in the 14 million light-year distant galaxy has been used to unravel the fate of star clusters whose bright young stars are spread through the disk of the galaxy as the clusters dissolve. The exploration of stars and clusters in external galaxy NGC 1313 offers clues to star formation and star cluster evolution in our own Milky Way.

wsbswdx

Orion's Cradle

Explanation: Cradled in glowing hydrogen, stellar nurseries in Orion lie at the edge of a giant molecular cloud some 1,500 light-years away. This breath-taking view spans about 13 degrees across the center of the well-known constellation with the Great Orion Nebula, the closest large star forming region, just right of center. The deep mosaic also includes (left of center), the Horsehead Nebula, the Flame Nebula, and Orion's belt stars. Image data acquired with a hydrogen alpha filter adds other remarkable features to this wide angle cosmic vista -- pervasive tendrils of energized atomic hydrogen gas and portions of the surrounding Barnard's Loop. While the Orion Nebula and belt stars are easy to see with the unaided eye, emission from the extensive interstellar gas is faint and much harder to record, even in telescopic views of the nebula-rich complex.

wsbswdx

The Magnificent Tail of Comet McNaught

Explanation: Comet McNaught, the Great Comet of 2007, has grown a long and filamentary tail. The spectacular tail spreads across the sky and is visible to Southern Hemisphere observers just after sunset. The head of the comet remains quite bright and easily visible to even city observers without any optical aide. The amazing tail is visible on long exposures and even to the unaided eye from a dark location. Reports even have the tail visible just above the horizon after sunset for many northern observers as well. Comet McNaught, estimated at magnitude -2 (minus two), was caught by the comet's discoverer in the above image just after sunset last Friday from Siding Spring Observatory in Australia. Comet McNaught, the brightest comet in decades, is now fading as it moves further into southern skies and away from the Sun and Earth.

wsbswdx

The Sombrero Galaxy in Infrared

Explanation: This floating ring is the size of a galaxy. In fact, it is part of the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light. The above image shows the infrared glow, recently recorded by the orbiting Spitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away. M104 can be seen with a small telescope in the direction of the constellation Virgo.

wsbswdx

Comet McNaught from New STEREO Satellite

Explanation: The brightest comet of recent decades was a surprising first sight for a new camera in space. The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument onboard the Solar TErrestrial RElations Observatory (STEREO) satellite had just opened up on January 11 when it snapped the above image of Comet McNaught. Visible was a spectacular view of the ion tail of Comet McNaught being swept away from the Sun by the solar wind in filamentary rays. The comet tail is seen to extend at least seven degrees across the above image, while the central coma is so bright it saturates. Comet McNaught is now reportedly so bright that it is visible even in broad daylight by blocking out the Sun with your hand. Comet McNaught has rounded the Sun and will slowly fade away for observers in Earth's Southern Hemisphere as it recedes from the Sun.

wsbswdx

Kepler's Supernova Remnant in X-Rays

Explanation: What caused this mess? Some type of star exploded to create the unusually shaped nebula known as Kepler's supernova remnant, but which type? Light from the stellar explosion that created this energized cosmic cloud was first seen on planet Earth in October 1604, a mere four hundred years ago. The supernova produced a bright new star in early 17th century skies within the constellation Ophiuchus. It was studied by astronomer Johannes Kepler and his contemporaries, with out the benefit of a telescope, as they searched for an explanation of the heavenly apparition. Armed with a modern understanding of stellar evolution, early 21st century astronomers continue to explore the expanding debris cloud, but can now use orbiting space telescopes to survey Kepler's supernova remnant (SNR) across the spectrum. Recent X-ray data and images of Kepler's supernova remnant taken by the orbiting Chandra X-ray Observatory has shown relative elemental abundances more typical of a Type Ia supernova, indicating that the progenitor was a white dwarf star that exploded when it accreted too much material and went over Chandrasekhar's limit. About 13,000 light years away, Kepler's supernova represents the most recent stellar explosion seen to occur within our Milky Way galaxy.

wsbswdx

Collinder 399: The Coat Hanger

Explanation: Is this coat hanger a star cluster or an asterism? This cosmic hang-up has been debated over much of last century, as astronomers wondered whether this binocular-visible object is really a physically associated open cluster or a chance projection. Chance star projections are known as asterisms, an example of which is the popular Big Dipper. Recent precise measurements from different vantage points in the Earth's orbit around the Sun have recently uncovered discrepant angular shifts indicating that the Coat Hanger is better described as an asterism. Known more formally as Collinder 399, this bright stellar grouping can be seen spanning more than a full moon toward the direction of the constellation of the Fox (Vulpecula). On the far right of the above image is the open cluster of stars NGC 6802.

wsbswdx

The Eagle Nebula in Infrared

Explanation: In visible light, the whole thing looks like an eagle. The region was captured recently in unprecedented detail in infrared light by the robotic orbiting Spitzer Space Telescope (SSC). Shown above, the infrared image allows observers to peer through normally opaque dust and so better capture the full complexity of the Eagle Nebula star forming region. In particular, the three famous pillars near the image center are seen bathed in dust likely warmed by a supernova explosion. The warm dust is digitally assigned the false color of red. Also visible, near the bottom of the image, is ten light-year long pillar sometimes dubbed the Fairy of Eagle Nebula. The greater Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of Serpens.

wsbswdx

NGC 602 and Beyond

Explanation: Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies 5 million year young star cluster NGC 602. Surrounded by natal gas and dust, NGC 602 is featured in this stunning Hubble image of the region. Fantastic ridges and swept back shapes strongly suggest that energetic radiation and shock waves from NGC 602's massive young stars have eroded the dusty material and triggered a progression of star formation moving away from the cluster's center. At the estimated distance of the Small Magellanic Cloud, the picture spans about 200 light-years, but a tantalizing assortment of background galaxies are also visible in the sharp Hubble view. The background galaxies are hundreds of millions of light-years or more beyond NGC 602.

wsbswdx

The Big Dipper

Explanation: Do you see it? This common question frequently precedes the rediscovery of one of the most commonly recognized configurations of stars on the northern sky: the Big Dipper. This grouping of stars is one of the few things that has likely been seen, and will be seen, by every generation. The Big Dipper is not by itself a constellation. Although part of the constellation of the Great Bear (Ursa Major), the Big Dipper is an asterism that has been known by different names to different societies. Five of the Big Dipper stars are actually near each other in space and were likely formed at nearly the same time. Connecting two stars in the far part of the Big Dipper will lead one to Polaris, the North Star, which is part of the Little Dipper. Relative stellar motions will cause the Big Dipper to slowly change its apparent configuration over the next 100,000 years.

wsbswdx

The Mysterious Rings of Supernova 1987A

Explanation: What's causing those odd rings in supernova 1987A? In 1987, the brightest supernova in recent history occurred in the Large Magellanic Clouds. At the center of the picture is an object central to the remains of the violent stellar explosion. When the Hubble Space Telescope was pointed at the supernova remnant in 1994, however, the existence of curious rings was confirmed. The origins of these rings still remains a mystery. Speculation into the cause of the rings includes beamed jets emanating from a dense star left over from the supernova, and a superposition of two stellar winds ionized by the supernova explosion.

wsbswdx

The Orion Deep Field

Explanation: Adrift 1,500 light-years away in one of the night sky's most recognizable constellations, the glowing Orion Nebula and the dark Horsehead Nebula are contrasting cosmic vistas. But even fainter filaments of glowing gas are easily traced throughout the region in this stunning composite image that includes exposures filtered to record emission from hydrogen atoms. The view reveals extensive nebulosities associated with the giant Orion Molecular Cloud complex, itself hundreds of light-years across. A magnificent emission region, the Orion Nebula (aka M42) lies at the upper right of the picture. Immediately to its left are a cluster of prominent bluish reflection nebulae sometimes called the Running Man. The Horsehead nebula appears as a dark cloud, a small silhouette notched against the long red glow left of center. Alnitak is the easternmost star in Orion's belt and the brightest star to the left of the Horsehead. Below Alnitak is the Flame Nebula, with clouds of bright emission and dramatic dark dust lanes. Completing the trio of Orion's belt stars, bluish Alnilam and Mintaka form a line with Alnitak, extending to the upper left.

wsbswdx

Central Cygnus

Explanation: Supergiant star Gamma Cygni lies at the center of the Northern Cross, famous asterism in the constellation Cygnus the Swan. Known by the proper name Sadr, the bright star also lies at the center of this gorgeous skyscape, featuring a complex of stars, dust clouds, and glowing nebulae along the plane of our Milky Way galaxy. The field of view spans over 3 degrees (six Full Moons) on the sky and includes emission nebula IC 1318 and open star cluster NGC 6910. Left of Gamma Cyg and shaped like two glowing cosmic wings divided by a long dark dust lane, IC 1318's popular name is understandably the Butterfly Nebula. Above and left of Gamma Cyg, are the young, still tightly grouped stars of NGC 6910. Some distance estimates for Gamma Cyg place it at around 750 light-years while estimates for IC 1318 and NGC 6910 range from 2,000 to 5,000 light-years.

wsbswdx

Light from the First Stars

Explanation: What were the first stars like? No one is yet sure. Our Sun is not a first-generation star. It is not even second generation. The first stars to appear in the universe likely came and went about 13 billion years ago. However, deep observations by the Spitzer Space Telescope in infrared light have detected a diffuse glow, possibly from first generation stars hundreds of times more massive than our Sun. The above image shows infrared background light with bright patches that might have originated from clusters of these first objects. Gray areas depict places where nearby foreground stars from our Milky Way Galaxy were digitally removed.

wsbswdx

NGC 6960: The Witch's Broom Nebula

Explanation: Ten thousand years ago, before the dawn of recorded human history, a new light must suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was an exploding star and record the colorful expanding cloud as the Veil Nebula. Pictured above is the west end of the Veil Nebula known technically as NGC 6960 but less formally as the Witch's Broom Nebula. The rampaging gas gains its colors by impacting and exciting existing nearby gas. The supernova remnant lies about 1400 light-years away towards the constellation of Cygnus. This Witch's Broom actually spans over three times the angular size of the full Moon. The bright star 52 Cygnus is visible with the unaided eye from a dark location but unrelated to the ancient supernova.

wsbswdx

A Year of Extraterrestrial Fountains and Flows

Explanation: The past year was extraordinary for the discovery of extraterrestrial fountains and flows -- some offering new potential in the search for liquid water and the origin of life beyond planet Earth.. Increased evidence was uncovered that fountains spurt not only from Saturn's moon Enceladus, but from the dunes of Mars as well. Lakes were found on Saturn's moon Titan, and the residual of a flowing liquid was discovered on the walls of Martian craters. The diverse Solar System fluidity may involve forms of slushy water-ice, methane, or sublimating carbon dioxide. Pictured above, the light-colored path below the image center is hypothesized to have been created sometime in just the past few years by liquid water flowing across the surface of Mars.

wsbswdx

Martian Analemma

Explanation: On planet Earth, an analemma is the figure-8 loop you get when you mark the position of the Sun at the same time each day throughout the year. But similarly marking the position of the Sun in the Martian sky would produce the simpler, stretched pear shape in this digital illustration, based on the Mars Pathfinder project's famous Presidential Panorama view from the surface. The simulation shows the late afternoon Sun that would have been seen from the Sagan Memorial Station once every 30 Martian days (sols) beginning on Pathfinder's Sol 24 (July 29, 1997). Slightly less bright, the simulated Sun is only about two thirds the size as seen from Earth, while the Martian dust, responsible for the reddish sky of Mars, also scatters some blue light around the solar disk.

wsbswdx

Alnitak, Alnilam, Mintaka

Explanation: Alnitak, Alnilam, and Mintaka, are the bright bluish stars from east to west (left to right) along the diagonal in this gorgeous cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie about 1,500 light-years away, born of Orion's well-studied interstellar clouds. In fact, clouds of gas and dust adrift in this region have intriguing and some surprisingly familiar shapes, including the dark Horsehead Nebula and Flame Nebula near Alnitak at the lower left. The famous Orion Nebula itself lies off the bottom of this star field that covers an impressive 4.4x3.5 degrees on the sky. The color picture was composited from digitized black and white photographic plates recorded through red and blue astronomical filters, with a computer synthesized green channel. The plates were taken using the Samuel Oschin Telescope, a wide-field survey instrument at Palomar Observatory, between 1987 and 1991.

wsbswdx

IC 5067: Emission Nebula Close-up

Explanation: This amazing skyscape lies along a bright ridge of emission in IC 5067, also known as The Pelican Nebula. Appropriately, the Pelican Nebula itself is part of a much larger, complex star-forming region about 2,000 light-years away in the high flying constellation Cygnus, the Swan. Cosmic dust clouds that span light-years seem to rise like mountains in the mist in this natural color view, recorded through broadband filters to produce an analogy to human color vision. The fantastic shapes are sculpted by winds and radiation from a hot, massive stars and the dominant red emission is due to atomic hydrogen gas. Placing your cursor on the image will bring up a false color image of the nebula made through narrowband filters that also map specific emission from sulfur and oxygen atoms. The mapped color image reveals even more details of the cosmic clouds and their composition.

wsbswdx

The Gegenschein

Explanation: If you look carefully enough, you can even see the glow of the Sun in the opposite direction. At night this glow is known as the gegenschein (German for "counter glow"), and can be seen as a faint glow in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above, the gegenschein is seen superposed toward the constellation of Pisces. The gegenschein is distinguished from zodiacal light by the high angle of reflection. During the day, a phenomenon similar to the gegenschein called the glory can be seen in reflecting air or clouds opposite the Sun from an airplane.