科普 神奇的宇宙----图片(每天更新中)

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Apollo 17's Moonship

Explanation: Awkward and angular looking, Apollo 17's lunar module Challenger was designed for flight in the vacuum of space. This picture from command module America, shows Challenger's ascent stage in lunar orbit. Small reaction control thrusters are at the sides of the moonship with the bell of the ascent rocket engine underneath. The hatch allowing access to the lunar surface is seen at the front, with a round radar antenna at the top. Mission commander Gene Cernan is just visible through the dark, triangular window. This spaceship performed gracefully, landing on the Moon and returning the Apollo astronauts to the orbiting command module in December of 1972. So where is Challenger now? Its descent stage remains at the Apollo 17 landing site, Taurus-Littrow. The ascent stage was intentionally crashed nearby after being jettisoned from the command module prior to the astronauts' return to planet Earth. Apollo 17's mission was the sixth and last time astronauts have landed on the Moon.

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The Tarantula Nebula

Explanation: First cataloged as a star, 30 Doradus is actually an immense star forming region in nearby galaxy The Large Magellanic Cloud. The region's spidery appearance is responsible for its popular name, the Tarantula Nebula, except that this tarantula is about 1,000 light-years across, and 180,000 light-years away in the southern constellation Dorado. If the Tarantual Nebula were at the distance of the Orion Nebula (1,500 light-years), the nearest stellar nursery to Earth, it would appear to cover about 30 degrees on the sky or 60 full moons. The spindly arms of the Tarantula Nebula surround NGC 2070, a cluster that contains some of the intrinsically brightest, most massive stars known. Intriguing details of the nebula's core can be seen in this remarkable skyscape, a composite of 31 hours of exposure time. This cosmic Tarantula also lies near the site of the closest recent supernova.

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Hauoli Makahiki Hou

Explanation: Fading sunlight, a young crescent Moon, and brilliant Venus shared the western sky in this view of 2005's final sunset from the top of Mount Haleakala, on Maui, Hawaii. Also known as the Sacred House of the Sun, Haleakala, is Maui's dormant volcano. At 10,000 feet the summit is an ideal site for astronomical observatories, and this scene also features the silhouette of the northern hemisphere Faulkes Telescope. Of particular interest to students the Faulkes Telescope is a 2-meter diameter instrument, dedicated to astronomy education, that can be remotely operated over the internet. The project is a joint effort between the Dill Faulkes Educational Trust and the University of Hawaii Institute for Astronomy. Of course on Haleakala, "Happy New Year" would be "Hauoli Makahiki hou" (how-oh-lee ma-ka-hee-key ho).

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Dark Terrain on Saturn's Iapetus

Explanation: Why are vast sections of Iapetus as dark as coal? No one knows for sure. Iapetus, the third largest moon of Saturn, was inspected again as the Saturn-orbiting robot Cassini spacecraft swooped past the enigmatic world again late last year. The dark material covers most of the surface visible in the above image, while the small portion near the top that appears almost white is of a color and reflectance more typical of Saturn's other moons. The unknown material covers about half of the 1,500 kilometer wide moon. The material is so dark that it reflects less than five percent of incident sunlight, yet overlays craters indicating that it was spread after the craters were formed. Iapetus has other unexplained features. The bright part of Iapetus is covered with unexplained long thin streaks. The orbit of Iapetus is also unusual, being tilted to the plane of Saturn's orbit by an unusually high fifteen degrees. A strange ridge about 13 kilometers high crosses much of Iapetus near the equator and is visible near the bottom. Oddly, this ridge is almost exactly parallel with Iapetus' equator. The exact shape of Iapetus remains undetermined, but images indicate that it is quite strange -- something like a walnut. Research into the formation and history of mysterious Iapetus is active and ongoing.

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A Sun Pillar Over Maine

Explanation: Have you ever seen a sun pillar? When the air is cold and the Sun is rising or setting, falling ice crystals can reflect sunlight and create an unusual column of light. Ice sometimes forms flat, six-sided shaped crystals as it falls from high-level clouds. Air resistance causes these crystals to lie nearly flat much of the time as they flutter to the ground. Sunlight reflects off crystals that are properly aligned, creating the sun-pillar effect. In the above picture taken late last month, a sun-pillar reflects light from a Sun setting over Bangor, Maine, USA.

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A Year at Saturn

Explanation: Arriving at Saturn in July of 2004, the Cassini spacecraft has now spent a year and a half exploring the magnificent rings and moons of the distant gas giant. The year 2005 began with Cassini's Huygens probe landing on Saturn's large moon Titan. Cassini's continuing series of close flybys also revealed details and discoveries across the surface of the smog shrouded moon. In fact, with a ringside seat throughout 2005, Cassini's cameras have made spectacular pictures of Titan along with Saturn's other moons and rings almost common place. But often, Saturn itself provided the most dramatic backdrop. In this view, Saturn's moon Dione lies in front of edge-on rings and the gas giant's cloud tops draped with broad ring shadows. Dione is 1,118 kilometers across and lies about 300,000 kilometers from the ring's edge.

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The Perseus Cluster of Galaxies

Explanation: Here is one of the largest objects that anyone will ever see on the sky. Each of these fuzzy blobs is a galaxy, together making up the Perseus Cluster, one of the closest clusters of galaxies. The cluster is seen through a foreground of faint stars in our own Milky Way Galaxy. Near the cluster center, roughly 250 million light-years away, is the cluster's dominant galaxy NGC 1275, seen here just left of picture center. A prodigious source of x-rays and radio emission, NGC 1275 accretes matter as gas and galaxies fall into it. The Perseus Cluster of Galaxies is part of the Pisces-Perseus supercluster spanning over 15 degrees and containing over 1,000 galaxies. At the distance of NGC 1275, this view covers about 1.5 million light-years.

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The Iris Nebula from CFHT

Explanation: Like delicate cosmic petals, these clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023, this is not the only nebula in the sky to evoke the imagery of flowers. Still, this beautiful digital image shows off the Iris Nebula's range of colors and symmetries in impressive detail. Within the Iris, dusty nebular material surrounds a massive, hot, young star in its formative years. Central filaments of cosmic dust glow with a reddish photoluminescence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Yet the dominant color of the nebula is blue, characteristic of dust grains reflecting starlight. Dark, obscuring clouds of dust and cold molecular gas are also present and can lead the eye to see other convoluted and fantastic shapes. Infrared observations indicate that this nebula may contain complex carbon molecules known as PAHs. As shown here, the Iris Nebula is about 6 light-years across.

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Smooth Sections on 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 is currently being visited by the Japanese spacecraft Hayabusa that is documenting its unusual structure and mysterious lack of craters. Last month, Hayabusa actually touched down on one of the smooth patches, dubbed the MUSES Sea, and collected soil samples that will eventually be returned to Earth for analysis. Unfortunately, the robot Hayabusa craft has been experiencing communications problems and so its departure for Earth has been delayed until 2007. Computer simulations show that 500-meter asteroid Itokawa may impact the Earth within the next few million years.

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IC 2118: The Witch Head Nebula

Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble -- maybe Macbeth should have consulted the Witch Head Nebula. This suggestively shaped reflection nebula is associated with the bright star Rigel in the constellation Orion. More formally known as IC 2118, the Witch Head Nebula glows primarily by light reflected from Rigel, located just outside the top right corner of the above image. Fine dust in the nebula reflects the light. The blue color is caused not only by Rigel's blue color but because the dust grains reflect blue light more efficiently than red. The same physical process causes Earth's daytime sky to appear blue, although the scatterers in Earth's atmosphere are molecules of nitrogen and oxygen. The nebula lies about 1000 light-years away.

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SN 1006: Supernova Remnant in X-Rays

Explanation: This huge puff ball was once a star. One thousand years ago, in the year 1006, a new star was recorded in the sky that today we know was really an existing star exploding. The resulting expanding gas from the supernova is still visible with telescopes today, continues to expand, and now spans over 70 light years. SN 1006 glows in every type of light. The above image of SN 1006 was captured by the orbiting Chandra Observatory in X-ray light. Even today, not everything about the SN 1006 is understood, for example why particle shocks that produce the bright blue filaments are only visible at some locations. SN 1006 is thought to have once been a white dwarf that exploded when gas being dumped onto it by its binary star companion caused it to go over the Chandrasekhar limit. Foreground stars are visible that have nothing to do with the supernova.

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The Mysterious Cone Nebula

Explanation: Sometimes the simplest shapes are the hardest to explain. For example, the origin of the mysterious cone-shaped region seen on the far left remains a mystery. The interstellar formation, dubbed the Cone Nebula, is located about 2700 light years away. Other features in the image include red emission from diffuse interstellar hydrogen, wispy filaments of dark dust, and bright star S Monocerotis, visible on the far right. Blue reflection nebulae surround the brighter stars. The dark Cone Nebula region clearly contains much dust which blocks light from the emission nebula and open cluster NGC 2264 behind it. One hypothesis holds that the Cone Nebula is formed by wind particles from an energetic source blowing past the Bok Globule at the head of the cone.

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Earthrise

Explanation: In December of 1968, the Apollo 8 crew flew from the Earth to the Moon and back again. Frank Borman, James Lovell, and William Anders were launched atop a Saturn V rocket on December 21, circled the Moon ten times in their command module, and returned to Earth on December 27. The Apollo 8 mission's impressive list of firsts includes: the first humans to journey to the Earth's Moon, the first manned flight using the Saturn V, and the first to photograph the Earth from deep space. As the Apollo 8 command module rounded the farside of the Moon, the crew could look toward the lunar horizon and see the Earth appear to rise, due to their spacecraft's orbital motion. The famous picture that resulted, of a distant blue Earth above the Moon's limb, was a marvelous gift to the world.

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Hydrogen and Dust in the Rosette Nebula

Explanation: At the edge of a large molecular cloud in Monoceros, some 3,000 light years away, dark filaments of dust are silhouetted by luminous hydrogen gas. The close up view of the Rosette Nebula dramatically suggests that star formation is an on going process in the region, with dark filaments sculpted by winds and radiation from hot, young stars. Ultraviolet radiation from the young stars also strips electrons from the surrounding hydrogen atoms. As electrons and atoms recombine they emit longer wavelength, lower energy light in a well known characteristic pattern of bright spectral lines. At visible wavelengths, the strongest emission line in this pattern is in the red part of the spectrum and is known as "Hydrogen-alpha" or just H-alpha. Part of IPHAS, a survey of H-alpha emission in our Milky Way Galaxy, this image spans about 25 light-years.

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Andromeda Island Universe

Explanation: The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy some two million light-years away. But without a telescope, even this immense spiral galaxy - spanning over 200,000 light years - appears as a faint, nebulous cloud in the constellation Andromeda. In contrast, a bright yellow nucleus, dark winding dust lanes, gorgeous blue spiral arms and star clusters are recorded in this stunning telescopic digital mosaic with a cumulative exposure of over 90 hours. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept only 80 years ago. Were these "spiral nebulae" simply outlying components of our own Milky Way Galaxy or were they instead "island universes" -- distant systems of stars comparable to the Milky Way itself? This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observations of M31 in favor of Andromeda, island universe.

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Sunrise by Season

Explanation: Does the Sun always rise in the same direction? No. As the seasons change, the direction toward the rising Sun will change, too. The Sun will always rise and set furthest to the south during the day of Winter Solstice, and furthest to the north during Summer Solstice. Today is Winter Solstice, the day of least sunlight in the Northern Hemisphere and of most sunlight in the Southern Hemisphere. In many countries, the Winter Solstice brings a change in season, as it is the first day of winter in the North. The solar heating and stored energy in the Earth's surface and atmosphere is near its lowest during winter, making it usually the coldest months of the year. On the brighter side in the north, daylight hours will increase every day from now until June. Pictured above are the different directions of the rising sun throughout the year above a small town in Greece.

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M83: The Southern Pinwheel Galaxy from VLT

Explanation: M83 is one of the closest and brightest spiral galaxies on the sky. Visible with binoculars in the constellation of Hydra, majestic spiral arms have prompted its nickname as the Southern Pinwheel. Although discovered 250 years ago, only much later was it appreciated that M83 was not a nearby gas cloud, but a barred spiral galaxy much like our own Milky Way Galaxy. M83, pictured above in a photograph from a Very Large Telescope, is a prominent member of a group of galaxies that includes Centaurus A and NGC 5253, all of which lie about 15 million light years distant. Several bright supernova explosions have been recorded in M83. An intriguing double circumnuclear ring has been discovered at the center of M83.

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GLIMPSE the Milky Way

Explanation: Scroll right and gaze through the dusty plane of our Milky Way Galaxy in infrared light. The cosmic panorama is courtesy of the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) project and the Spitzer Space Telescope. The galactic plane itself runs through the middle of the false-color view that spans nine degrees (about 18 full moons) across the southern constellation Norma. Spitzer's infrared cameras see through much of the galaxy's obscuring dust revealing many new star clusters as well as star forming regions (bright white splotches) and hot interstellar hydrogen gas (greenish wisps). The pervasive red clouds are emission from dust and organic molecules, pocked with holes and bubbles blown by energetic outflows from massive stars. Intensely dark patches are regions of dust too dense for even Spitzer's infrared vision to penetrate.

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Apollo 17: Last on the Moon

Explanation: In December of 1972, Apollo 17 astronauts Eugene Cernan and Harrison Schmitt spent about 75 hours on the Moon, in the Taurus-Littrow valley, while colleague Ronald Evans orbited overhead. Near the beginning of their third and final excursion across the lunar surface, Schmitt took this picture of Cernan flanked by an American flag and their lunar rover's umbrella-shaped high-gain antenna. The prominent Sculptured Hills lie in the background while Schmitt's reflection can just be made out in Cernan's helmet. The Apollo 17 crew returned with 110 kilograms of rock and soil samples, more than from any of the other lunar landing sites. Cernan and Schmitt are still the last to walk on the Moon.

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A Digital Opportunity Rover on Mars

Rover Model: D. Maas - Synthetic Image: Z. Gorjian, K. Kuramura, M. Stetson, E. De Jong.
Explanation: If you could see one of the robot rovers currently rolling across Mars, what would it look like? To gain this perspective useful in planning explorations, the above synthetic image was produced digitally. Above, a digital model of the Opportunity rover was added to a real image of the inside of Endurance Crater on Mars taken earlier by Opportunity itself. The size of the six-wheeled robot was scaled to the size of the tracks that the Opportunity rover actually created. In actuality, both the Opportunity and Spirit rovers currently rolling across Mars each span about two meters and so are similar in size to a large rolling desk. Also visible in the image is dark soil, ancient light rock and numerous small gray pellets known as blueberries.