科普 神奇的宇宙----图片(每天更新中)

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Schwassmann-Wachmann 3: Fragment B

Explanation: Periodic comet 73P/Schwassmann-Wachmann 3 has fallen apart before. A cosmic souffle of ice and dust left over from the early solar system, this comet was seen to split into several large pieces during the close-in part of its orbit in 1995. However, this time the comet seems to be rapidly disintegrating with over three dozen fragments, named alphabetically, now stretching several degrees across the sky. Since comets are relatively fragile, stresses from heat and gravity and outgassing, for example, could be responsible for their tendency to breakup in such a spectacular fashion. On April 18th, the Hubble Space Telescope recorded this sharp view of prolific Fragment B, itself trailing dozens of smaller pieces, each with its own cometary coma and tail. The picture spans over 3,000 kilometers at the comet's April 18 distance of 32 million kilometers from planet Earth. With its brightest fragment presently too faint to be seen with the naked eye, comet Schwassmann-Wachmann 3 will pass closest to Earth on May 13 at a distance of about 11 million kilometers.

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Saturn in Blue and Gold

Explanation: Why is Saturn partly blue? The above picture of Saturn approximates what a human would see if hovering close to the giant ringed world. The above picture was taken in mid-March by the robot Cassini spacecraft now orbiting Saturn. Here Saturn's majestic rings appear directly only as a thin vertical line. The rings show their complex structure in the dark shadows they create on the image left. Saturn's fountain moon Enceladus, only about 500 kilometers across, is seen as the bump in the plane of the rings. The northern hemisphere of Saturn can appear partly blue for the same reason that Earth's skies can appear blue -- molecules in the cloudless portions of both planet's atmospheres are better at scattering blue light than red. When looking deep into Saturn's clouds, however, the natural gold hue of Saturn's clouds becomes dominant. It is not known why southern Saturn does not show the same blue hue -- one hypothesis holds that clouds are higher there. It is also not known why Saturn's clouds are colored gold.

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Sunspot 875 Flares

Explanation: An unusually active sunspot region is now crossing the Sun. The region, numbered 875, is larger than the Earth and has produced several solar flares over the past week. It should take a few more days for Sunspot 875 to finish crossing the solar disk. The above image of the Sun was taken last Wednesday in a very specific color of red light to bring up detail. Sunspot 875, in the midst of erupting a large Class C solar flare, can be seen as the dark region to the upper right. In the above image, relatively cool regions appear dark while hot regions appear bright. On the far left, solar prominences are visible hovering above the Sun's surface.

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Open Cluster NGC 290: A Stellar Jewel Box

Explanation: Jewels don't shine this bright -- only stars do. Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and color. The photogenic cluster, pictured above, was captured recently by the orbiting Hubble Space Telescope. Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars. NGC 290 lies about 200,000 light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC). The open cluster contains hundreds of stars and spans about 65 light years across. NGC 290 and other open clusters are good laboratories for studying how stars of different masses evolve, since all the open cluster's stars were born at about the same time.

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1006 AD: Supernova in the Sky

Explanation: A new star, likely the brightest supernova in recorded human history, appeared in planet Earth's sky about 1,000 years ago today, in 1006 AD. The expanding debris cloud from the stellar explosion is still visible to modern astronomers, but what did the supernova look like in 1006? In celebration of the millennial anniversary of SN1006, astronomer Tunc Tezel offers this intriguing suggestion, based on a photograph he took on February 22, 1998 from a site overlooking the Mediterranean south of Antalya, Turkey. On that date, bright Venus and a waning crescent Moon shone in the early morning sky. Adopting calculations which put the supernova's apparent brightness between Venus and the crescent Moon, he digitally superposed an appropriate new star in the picture. He placed the star at the supernova's position in the southerly constellation of Lupus and used the water's reflection of moonlight in the final image.

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NGC 7635: Bubble in a Cosmic Sea

Color Composite: Davide De Martin (Skyfactory)
Explanation: Seemingly adrift in a cosmic sea of stars and glowing gas, the delicate, floating apparition near the center (next to a blue tinted star) of this widefield view is cataloged as NGC 7635 - The Bubble Nebula. A mere 10 light-years wide, the tiny Bubble Nebula and the larger complex of interstellar gas and dust clouds are found about 11,000 light-years distant, straddling the boundary between the parental constellations Cepheus and Cassiopeia. Also included in the breathtaking vista is open star cluster M52 (upper left), some 5,000 light-years away. The digital color picture is based on photographic plates taken at the Palomar Observatory between 1992 and 1997. This cropped version spans about 2.7 degrees on the sky corresponding to a width of just over 500 light-years at the estimated distance of the Bubble Nebula.

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NGC 4696: Energy from a Black Hole

Explanation: In many cosmic environments, when material falls toward a black hole energy is produced as some of the matter is blasted back out in jets. In fact, such black hole "engines" appear to be the most efficient in the Universe, at least on a galactic scale. This composite image illustrates one example of an elliptical galaxy with an efficient black hole engine, NGC 4696. The large galaxy is the brightest member of the Centaurus galaxy cluster, some 150 million light-years away. Exploring NGC 4696 in x-rays (red) astronomers can measure the rate at which infalling matter fuels the supermassive black hole and compare it to the energy output in the jets to produce giant radio emitting bubbles. The bubbles, shown here in blue, are about 10,000 light-years across. The results confirm that the process is much more efficient than producing energy through nuclear reactions - not to mention using fossil fuels. Astronomers also suggest that as the black hole pumps out energy and heats the surrounding gas, star formation is ultimately shut off, limiting the size of large galaxies like NGC 4696.

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Open Cluster NGC 290: A Stellar Jewel Box


Explanation: Jewels don't shine this bright -- only stars do. Like gems in a jewel box, though, the stars of open cluster NGC 290 glitter in a beautiful display of brightness and color. The photogenic cluster, pictured above, was captured recently by the orbiting Hubble Space Telescope. Open clusters of stars are younger, contain few stars, and contain a much higher fraction of blue stars than do globular clusters of stars. NGC 290 lies about 200,000 light-years distant in a neighboring galaxy called the Small Cloud of Magellan (SMC). The open cluster contains hundreds of stars and spans about 65 light years across. NGC 290 and other open clusters are good laboratories for studying how stars of different masses evolve, since all the open cluster's stars were born at about the same time.
疏散星团: 一个恒星珠宝盒

说明: 珠宝无这般绚烂，唯有恒星会如斯。如同珠宝盒中的珍宝，疏散星团NGC 290内的恒星，美丽地闪烁着各种不同的光芒和颜色。这个很上镜星团的影像，是最近由哈伯太空望远镜拍摄。疏散星团内的恒星通常较年轻、数量较少、拥有和球状星团比起来较高比率的蓝色恒星。NGC 290位在邻近的小麦哲伦星系内，离我们约有二十万光年。这个疏散星团有数百颗成员星，跨度大约有65光年。NGC 290及其它疏散星团，是研究不同质量的恒星如何演化的好实验室，因为疏散星团的恒星大约都是在同一时间诞生的。

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Schwassmann-Wachmann 3: Fragment B


Explanation: Periodic comet 73P/Schwassmann-Wachmann 3 has fallen apart before. A cosmic souffle of ice and dust left over from the early solar system, this comet was seen to split into several large pieces during the close-in part of its orbit in 1995. However, this time the comet seems to be rapidly disintegrating with over three dozen fragments, named alphabetically, now stretching several degrees across the sky. Since comets are relatively fragile, stresses from heat and gravity and outgassing, for example, could be responsible for their tendency to breakup in such a spectacular fashion. On April 18th, the Hubble Space Telescope recorded this sharp view of prolific Fragment B, itself trailing dozens of smaller pieces, each with its own cometary coma and tail. The picture spans over 3,000 kilometers at the comet's April 18 distance of 32 million kilometers from planet Earth. With its brightest fragment presently too faint to be seen with the naked eye, comet Schwassmann-Wachmann 3 will pass closest to Earth on May 13 at a distance of about 11 million kilometers.
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史瓦三号彗星的碎片B
说明: 周期性彗星73P/史瓦三号彗星 (73P/Schwassmann-Wachmann 3)先前就裂解过。这团宇宙级奶酥是初期太阳系所遗留下来的，它在1995年回归时裂解成数块大型的碎片。在此次回归，这颗彗星进一步快速裂解成三十多个碎片，散布在数度的天区内，并以英文字母依序加以命名。因为彗星相当脆弱，热、重力、及排气都有可能让它们发生这种大规模的裂解。哈伯太空望远镜在4月18日，为"多产"的碎片B记录了这幅清晰影像。它后面跟随着数十颗小碎片，每一颗都有自已的彗发和彗尾。在4月18日拍摄时，彗星离地球约有3千2百万公里，影像涵盖了略大于三千公里的区域。现在史瓦三号彗星最亮的碎片肉眼已不得见。它将在5月13日行进到靠地球最近的位置，距离大约是一千一百万公里。

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M31: The Andromeda Galaxy


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 million years for light to reach us from there. Although visible without aid, the above image of M31 is a digital mosaic of 20 frames taken with a small telescope. Much about M31 remains unknown, including how the center acquired two nuclei.

M31：仙女座星系

说明: 仙女座星系是最靠近银河系的一个大星系。一般认为银河系非常像仙女座星系。这两个星系正主控着一个称为本星系团的星系群。从仙女座星系所散播出来的光线是由数千亿颗恒星的光所组合而成。图片中分布在仙女座星系 周围的不同恒星是从地球看出去的前景星，它们都是银河系中的恒星。仙女座星系经常被称为M31，这是由于他在 梅西尔弥漫星体的星表上是排第31个。M31与地球的距离是那么的遥远，他的光大约要经过200万年才能到达地球。关于M31，仍存在许多未知现象，例如 为什么他的中心有两个核心。

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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.


红外光波段的墨西哥帽星系

说明: 这个飘浮的环大小和星系相当。更具体的说，它是很上镜的墨西哥帽星系的一部份；墨西哥帽星系(Sombrero Galaxy)是邻近室女座星系团最大的星系之一。可见光波段环绕在墨西哥帽星系腰部的黝黑尘埃带，在红外光波段却变得非常明亮。上面影像中的假色红外辉光是来自史匹哲太空望远镜之观测，影像其余部份则是来自美国太空总署的哈伯太空望远镜在先前拍摄之可见光照片。墨西哥帽星系又称为M104，离我们约有二千八百万光年远，大小有五万光年。M104位在北天的室女座，用小口径望远镜就能看见它。

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396



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.
火星的日行迹
说明: 在地球上，如果每天同一时间在同一地点记录太阳的位置，一年过后，就会得到一个8字型的日行迹 (analemma)。 如果在火星上进行类似的工作，所得到的图案会简单一些，它会是个被拉长的梨形。这张以火星探路者号著名火星全景图为背景的示意图，呈现了火星日行迹的形状。 这张模拟图假设是从萨根记念站 (Sagan Memorial Station)观看傍晚的太阳，如果每隔30个火星日记录一次 (首次在地球历1997年7月29日)，就会形成上面的景像。 从模拟可知火星的太阳没地球亮，太阳的大小只有地球的三分之一。除此之外，火星的尘埃也让天空变得红红的，并且会散射来自太阳盘面的蓝光。

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Eiffel Moon
Explanation: Celestial and terrestrial lights are featured in this stunning image that includes the Moon in phases of the total lunar eclipse of March 3rd. In the foreground, the distinctively-shaped Eiffel Tower, over 300 meters tall, is a well-known tourist destination and one of the most visited buildings in the world. Of course the Moon is even more recognizable, but harder to visit. The last lunar tour was undertaken nearly 35 years ago, during the Apollo 17 mission.

艾菲尔铁塔上空的月食

说明: 这张记录了天体和地球辉光的精彩照片，也呈现了3月3日月全食的过程。 在前景，标高超过三百公尺、形状特异的艾菲尔铁塔，是著名的游客景点，也是世界上访客最多的建筑物之一。 当然月亮的知名度更高，不过到访的难度也较高，最近一次的月球之旅是35年前的阿波罗十七号任务。

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Aurora Over Alaska

Explanation: Higher than the highest mountain, higher than the highest airplane, lies the realm of the aurora. Aurora rarely reach below 60 kilometers, and can range up to 1000 kilometers. Aurora light results from solar shockwave causing energetic electrons and protons to striking molecules in the Earth's atmosphere. Frequently, when viewed from space, a complete aurora will appear as a circle around one of the Earth's magnetic poles. The above digitally enhanced photograph was taken in 2005 January shows a spectacular aurora borealis above the frozen landscape of Bear Lake, Alaska, USA. The above image was voted Wikipedia Commons Picture of the Year for 2006.
阿拉斯加上空的极光
说明 : 比最高山峰更高，比最高的飞机更高的上方是极光的王国。极光很少低于60公里高，却能高达1000公里。极光来自于阳光冲击波产生的能量电子和质子激发的大气层分子。通常，从太空望去，完整的极光像一个环包围地球的一极。数字处理过的上图是2005一月摄于美国阿拉斯加冰冻的Bear湖，显示了引人入胜的北方极光。上图被选作Wikipedia 2006年的公共照片。

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M82: Galaxy with a Supergalactic Wind

Acknowledgement: M. Mountain (STScI), P. Puxley (NSF), J. Gallagher (U. Wisconsin)
Explanation: What's lighting up the Cigar Galaxy? M82, as this irregular galaxy is also known, was stirred up by a recent pass near large spiral galaxy M81. This doesn't fully explain the source of the red-glowing outwardly expanding gas, however. Recent evidence indicates that this gas is being driven out by the combined emerging particle winds of many stars, together creating a galactic "superwind." The above photographic mosaic, released yesterday to commemorate the sixteenth anniversary of the Hubble Space Telescope, highlights a specific color of red light strongly emitted by ionized hydrogen gas, showing detailed filaments of this gas. The filaments extend for over 10,000 light years. The 12-million light-year distant Cigar Galaxy is the brightest galaxy in the sky in infrared light, and can be seen in visible light with a small telescope towards the constellation of Ursa Major.

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Crumbling Comet Schwassmann-Wachmann 3 Approaches

Explanation: A crumbling comet will soon pass near the Earth. Comet 73P/Schwassmann-Wachmann 3 is brightening and may even be visible to the unaided eye when the fragmented comet zooms past Earth during the middle of next month. Still, the small comet poses no Earth hazard, since it will pass the Earth at about 25 times the distance of the Moon. Exactly how bright Comet Schwassman-Wachmann 3 will get is unknown. It is even possible, althought unlikely, that debris from the comet will have spread out enough to cause a notable meteor shower. Pictured above, Fragment B of Comet Schwassman-Wachmann 3 was photographed two nights ago by a 8.2-meter Very Large Telescope in Chile. Visible to the lower right of the large B fragment are many mini-comets that have broken off and now orbit the Sun separately. Each mini-comet itself sheds gas and dust and so appears to have its own hazy coma. The comet will pass closest to the Sun on June 7.

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The Solar Spectrum

Explanation: It is still not known why the Sun's light is missing some colors. Shown above are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device. The above spectrum was created at the McMath-Pierce Solar Observatory and shows, first off, that although our yellow-appearing Sun emits light of nearly every color, it does indeed appear brightest in yellow-green light. The dark patches in the above spectrum arise from gas at or above the Sun's surface absorbing sunlight emitted below. Since different types of gas absorb different colors of light, it is possible to determine what gasses compose the Sun. Helium, for example, was first discovered in 1870 on a solar spectrum and only later found here on Earth. Today, the majority of spectral absorption lines have been identified - but not all.

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Star Clouds over Arizona

Explanation: The clouds in the foreground are much different than the clouds in the background. In the foreground are a photogenic deck of Earth-based water clouds. The long exposure used to create the above photograph makes the light from the left, reflected from Phoenix, Arizona, USA, appear like a sunset. Far in the distance, however, are star clouds from the disk of our Milky Way Galaxy. Billions of stars like our Sun live there, circling our Galactic center every 200 million years. Contrast between the water clouds and the star clouds has been digitally enhanced. Between the two, visible on the upper right, is the planet Jupiter.

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Z is for Mars

Explanation: This composite of images spaced about a week apart - from late July 2005 (bottom right) through February 2006 (top left) - traces the retrograde motion of ruddy-colored Mars through planet Earth's night sky. On November 7th, 2005 the Red Planet was opposite the Sun in Earth's sky (at opposition). That date occurred at the center of this series with Mars near its closest and brightest. But Mars didn't actually reverse the direction of its orbit to trace out the Z-shape. Instead, the apparent backwards or retrograde motion with respect to the background stars is a reflection of the motion of the Earth itself. Retrograde motion can be seen each time Earth overtakes and laps planets orbiting farther from the Sun, the Earth moving more rapidly through its own relatively close-in orbit. The familiar Pleiades star cluster lies at the upper left.

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NGC 253: Dusty Island Universe

Explanation: Shiny NGC 253, sometimes called the Silver Dollar Galaxy, is one of the brightest spiral galaxies visible - and also one of the dustiest. First swept up in 1783 by mathematician and astronomer Caroline Herschel, the dusty island universe lies a mere 10 million light-years away in the southern constellation Sculptor. About 70 thousand light-years across, NGC 253 is the largest member of the Sculptor Group of Galaxies, the nearest to our own Local Group of Galaxies. In addition to its spiral dust lanes, striking tendrils of dust seem to be rising from the galactic disk in this gorgeous view. The high dust content accompanies frantic star formation, giving NGC 253 the designation of a starburst galaxy. NGC 253 is also known to be a strong source of high-energy x-rays and gamma rays, likely due to massive black holes near the galaxy's center.