科普 神奇的宇宙----图片(每天更新中)

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Mercury and the Chromosphere

Explanation: Enjoying Wednesday's transit of Mercury from Dallas, Texas, astronomer Phil Jones recorded this detailed image of the Sun. Along with a silhouette of the innermost planet, a network of cells and dark filaments can be seen against a bright solar disk with spicules and prominences along the Sun's edge. The composited image was taken through a telescope equiped with an H-alpha filter that narrowly transmits only the red light from hydrogen atoms. Such images emphasize the solar chromosphere, the region of the Sun's atmosphere immediately above its photosphere or normally visible surface. Left of center, the tiny disk of Mercury seems to be imitating a small sunspot that looks a little too round. But in H-alpha pictures, sunspot regions are usually dominated by bright splotches (called plages) on the solar chromosphere.

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The Ghostly Tail of Comet SWAN

Explanation: What causes the structure in Comet SWAN's tail? Comet SWAN, which unexpectedly flared up to naked-eye brightness last week, has been showing detail in its ion tail that might be described as ghostly. The ion tail is made of ionized gas, energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind itself is quite structured and sculpted by the Sun's complex and ever changing magnetic field. Following the wind, structure in Comet SWAN's tail can be seen to move outward from the Sun even alter its wavy appearance over time. The blue color of the ion tail is dominated by recombining carbon monoxide atoms. The color of the coma surrounding the head of the comet is tinged green by slight amounts of the molecule cyanogen. The above image was taken last week from California, USA. This week may be the best remaining chance for northern hemisphere observers to see the fading interplanetary snowball. SWAN has now passed both the Earth and the Sun and will fade as it moves away from the Earth and heads out into the vast space between the stars.

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A Galaxy Collision in NGC 6745

Explanation: Galaxies don't normally look like this. NGC 6745 actually shows the results of two galaxies that have been colliding for only hundreds of millions of years. Just off the above photograph to the lower right is the smaller galaxy, moving away. The larger galaxy, pictured above, used to be a spiral galaxy but now is damaged and appears peculiar. Gravity has distorted the shapes of the galaxies. Although it is likely that no stars in the two galaxies directly collided, the gas, dust, and ambient magnetic fields do interact directly. In fact, a knot of gas pulled off the larger galaxy on the lower right has now begun to form stars. NGC 6745 spans about 80 thousand light-years across and is located about 200 million light-years away.

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V838 Mon: Echoes from the Edge

Explanation: Variable star V838 Monocerotis lies near the edge of our Milky Way Galaxy, about 20,000 light-years from the Sun. Still, ever since a sudden outburst was detected in January 2002, this enigmatic star has taken the center of an astronomical stage. As astronomers watch, light from the outburst echoes across pre-existing dust shells around V838 Mon, progressively illuminating ever more distant regions. This stunning image of swirls of dust surrounding the star was recorded by the Hubble Space Telescope in September of this year. The picture spans about 14 light-years. Astronomers expect the expanding echoes to continue to light up the dusty environs of V838 Mon for at least the rest of the current decade. Researchers have now found that V838 Mon is likely a young binary star, but the cause of its extraordinary outburst remains a mystery.

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Messier 76

Explanation: "Nebula at the right foot of Andromeda ... " begins the description for the 76th object in Charles Messier's 18th century Catalog of Nebulae and Star Clusters. In fact, M76 is one of the fainter objects on the Messier list and is also known by the popular name of the "Little Dumbbell Nebula". Like its brighter namesake M27 (the Dumbbell Nebula), M76 is recognized as a planetary nebula - a gaseous shroud cast off by a dying sunlike star. The nebula itself is thought to be shaped more like a donut, while its box-like appearance is due to our nearly edge-on view. Gas expanding more rapidly away from the donut hole produces the faint loops of far flung material. The nebula's dying star can be picked out in this sharp color image as the bottom, blue-tinted member of the double star near the center of the box-like shape. Distance estimates place M76 about 3 to 5 thousand light-years away, making the nebula over a light-year in diameter.

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McMurdo Panorama from Mars

Explanation: This was Spirit's view on Martian-day 1,000 of its 90-Martian-day mission. The robotic Spirit rover has stayed alive so long on Mars that it needed a place to wait out the cold and dim Martian winter. Earth scientists selected Low Ridge hill, a place with sufficient slant to give Spirit's solar panels enough sunlight to keep powered up and making scientific observations. From its Winter Haven, Spirit has been able to build up the above 360-degree panorama, which has been digitally altered to exaggerate colors and compressed horizontally to fit your screen. The long winter is finally ending in the south of Mars, and with the increasing sunlight plans are now being made for Spirit to further explore the rocky Columbia Hills inside intriguing Gusev crater.

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Mysterious Acid Haze on Venus

Explanation: Why did an acidic haze spread across Venus? The unusual clouds were discovered last July by ESA's robotic Venus Express spacecraft currently orbiting Venus. The bright and smooth haze was found by Venus Express to be rich in sulfuric acid, created when an unknown process lifted water vapor and sulphur dioxide from lower levels into Venus' upper atmosphere. There, sunlight broke these molecules apart and some of them recombined into the volatile sulfuric acid. Over the course of just a few days last July, the smooth acidic clouds spread from the South Pole of Venus across half the planet. The above false-color picture of Venus was taken last July 23rd in ultraviolet light, and shows the unusual haze as relatively smooth regions across the image bottom. The cause of the dark streaks in the clouds is also not yet understood and is being researched.

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SH2 136: A Spooky Nebula

Explanation: The dark nebula SH2-136 appears to be celebrating Halloween all of the time. The complex process of star formation create dust clouds of many shapes and sizes -- it is human perception that might identify a ghoulish creature, on the right of the above image, chasing humans. Halloween's modern celebration retains historic roots in dressing to scare away the spirits of the dead. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With our modern calendar, however, the real cross-quarter day will occur next week. Other cross-quarter markers include Groundhog Day and Walpurgis Night.

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The Sun Puffs

Explanation: Our Earth endures bursts of particles from the Sun. On 1997 April 7, at 10 am (EDT), ground monitors of the SOHO spacecraft, which continually monitors the Sun, noticed a weak spot in the solar corona was buckling again, this time letting loose a large, explosive Coronal Mass Ejection (CME). Almost simultaneously, NASA's WIND spacecraft began detecting bursts of radio waves from electrons involved in this magnetic storm. Supersonic waves rippled though the solar corona as a puff of high energy gas shot out into the Solar System. The above image shows two photographs of the Sun taken about 15 minutes apart and subtracted, highlighting the explosion. CME's are not unusual. The CME gas had little lasting effect on the Earth, but likely created fleeting, if not picturesque, Earth auroras.

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Comet SWAN Outburst

Explanation: Near its closest approach to planet Earth, comet SWAN (C/2006 M4) brightened unexpectedly earlier this week, becoming visible to naked-eye observers under dark night skies. Telescopic observers also noticed dramatic changes in the comet's colorful coma and tail, seen in this view recorded on October 25th. To make the picture, images totaling eight minutes in exposure time were stacked and centered on the comet as it moved relatively quickly against the background star field. The picture covers about 1 degree on the sky. Northern hemisphere observers should still find the comet an easy binocular target in the early evening, even though moonlight will increase the overall sky brightness in the next few days. Look toward the northwestern horizon and the constellation Hercules.

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The Spider and The Fly

Explanation: Star clusters and nebulae abound in the ancient northern constellation Auriga - a region that includes the interesting pair NGC 1931 (lower left) and IC 417. In this gorgeous color image, an imaginative eye toward the expansive IC 417 and diminutive NGC 1931 suggests a cosmic spider and fly. About 10,000 light-years distant, both are young open star clusters formed in interstellar clouds and still embedded in glowing hydrogen gas. The more compact NGC 1931 is about 10 light-years across with contrasting blue hues characteristic of dust reflected starlight.

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Composite Crab

Explanation: The Crab Nebula is cataloged as M1, the first object on Charles Messier's famous list of things which are not comets. In fact, the Crab is now known to be a supernova remnant, expanding debris from the death explosion of a massive star. This intriguing false-color image combines data from space-based observatories, Chandra, Hubble, and Spitzer, to explore the debris cloud in x-rays (blue-purple), optical (green), and infrared (red) light. One of the most exotic objects known to modern astronomers, the Crab Pulsar, a neutron star spinning 30 times a second, is the bright spot near picture center. Like a cosmic dynamo, this collapsed remnant of the stellar core powers the Crab's emission across the electromagnetic spectrum. Spanning about 12 light-years, the Crab Nebula is 6,500 light-years away in the constellation Taurus.

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Help Search for Interstellar Dust

Explanation: What caused that hole? The hole in question appears as a small dark circle on the far right. If the above image of aerogel seems dull and uninteresting, then welcome to one aspect of real world science. The interesting part is that something created that dark hole, and it might well be one of the first pieces of matter ever captured from outside our Solar System. Whatever created that hole was captured by the aerogel of the robotic Stardust spacecraft that flew across our Solar System for years and then returned a capsule to Earth. Scientists are now poring over the aerogel, looking to see what particles have become trapped. Many particles are surely from local Comet Wild 2, which Stardust flew past in 2004. Just a few particles, though, perhaps 10 or less, are expected to be from outside our Solar System. It is so difficult to find them that the Stardust team has created a downloadable interactive microscope program to allow anyone with a standard computer to help inspect aerogel slices and look for interstellar dust tracks. Good candidate tracks will later be inspected in great detail by members of the Stardust team.

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The Antennae Galaxies in Collision

Explanation: Two galaxies are squaring off in Corvus and here are the latest pictures. When two galaxies collide, however, the stars that compose them usually do not. This is because galaxies are mostly empty space and, however bright, stars only take up only a small amount of that space. During the slow, hundred million year collision, however, one galaxy can rip the other apart gravitationally, and dust and gas common to both galaxies does collide. In the above clash of the titans, dark dust pillars mark massive molecular clouds are being compressed during the galactic encounter, causing the rapid birth of millions of stars, some of which are gravitationally bound together in massive star clusters.

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Star EGGs in the Eagle Nebula

Explanation: Where do stars form? One place, star forming regions known as "EGGs", are uncovered at the end of this giant pillar of gas and dust in the Eagle Nebula (M16). EGGs, short for evaporating gaseous globules, are dense regions of mostly molecular hydrogen gas that fragment and gravitationally collapse to form stars. Light from the hottest and brightest of these new stars heats the end of the pillar and causes further evaporation of gas - revealing yet more EGGs and more young stars. This picture was taken by the Wide Field and Planetary Camera on board the Hubble Space Telescope.

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Tombaugh 4

Explanation: Clyde Tombaugh discovered planet Pluto in 1930 while surveying the skies with the 13-inch Lawrence Lowell Telescope. But the skilled and careful astronomer also went on to discover star clusters, comets, asteroids, and clusters of galaxies. For example, pictured is galactic or open star cluster Tombaugh 4 in the northern constellation Cassiopeia. Published in 1941, Tombaugh's description, based on his photographic images from the Lowell 13-inch, indicates the cluster is small and faint, and comprised of about 30 stars. Using the apparent brightness of the cluster stars he estimated the distance to be 20 to 30 thousand light-years, making Tombaugh 4 over 10 light-years in diameter. This deep color image, made with a modern ccd camera and another 13-inch telescope, includes the region's foreground stars and faint nebulosities.

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The Eagle Nebula in Hydrogen Oxygen, and Sulfur

Explanation: Bright blue stars are still forming in the dark pillars of the Eagle Nebula. Made famous by a picture from the Hubble Space Telescope in 1995, the Eagle Nebula shows the dramatic process of star formation. The above picture taken by a 0.8-meter telescope in the Canary Islands captures part of M16, the open cluster of stars that is being created. The high amount of detail in the above image results from it being taken only in specific colors of light emitted by hydrogen, oxygen, and sulfur. The bright blue stars of M16 have been continually forming over the past 5 million years, most recently in the famous central gas and dust columns that have been informally dubbed the Pillars of Creation and the Fairy. Light takes about 7,000 years to reach us from M16, which spans about 20 light years and can be seen with binoculars toward the constellation of the Serpent (Serpens).

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IC 4628: The Prawn Nebula

Explanation: South of Antares, in the tail of the nebula-rich constellation Scorpius, lies emission nebula IC 4628. Nearby hot, massive stars, millions of years young, radiate the nebula with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow. This narrow band image adopts a typical false-color mapping of the atomic emission, showing hydrogen emission in green hues, sulfur as red and oxygen as blue. At an estimated distance of 6,000 light-years, the region shown is about 250 light-years across. The nebula is also cataloged as Gum 56 for Australian astronomer Colin Stanley Gum, but seafood-loving astronomers might know this cosmic cloud as The Prawn Nebula.

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SWAN Meets Galaxy

Explanation: This cosmic portrait recorded October 9th features the lovely blue-green coma of Comet SWAN posing with spiral galaxy NGC 5005 in the northern constellation Canes Venatici. At the time the comet (center) was in the close foreground, a mere 9 light-minutes from planet Earth, with the galaxy a more substantial 60 million light-years distant. Not actually related to a bird, Comet SWAN (C/2006 M4) was so named as it was first spotted in image data from the SWAN (Solar Wind ANisotropies) camera aboard the sun-staring SOHO spacecraft. Having rounded the Sun, this comet is headed for interstellar space, but first it will make its closest approach to Earth on October 24. With binoculars, northern hemisphere observers can now spot the comet above the northwestern horizon, near the handle of the Big Dipper in the early evening sky.

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NGC 7635: The Bubble

Explanation: What created this huge space bubble? Blown by the wind from a star, this tantalizing, ghostly apparition is cataloged as NGC 7635, but known simply as The Bubble Nebula. Astronomer Eric Mouquet's striking view utilizes a long exposure with hydrogen alpha light to reveal the intricate details of this cosmic bubble and its environment. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Seen here above and right of the Bubble's center is a bright hot star embedded in reflecting dust. A fierce stellar wind and intense radiation from the star, which likely has a mass 10 to 20 times that of the Sun, has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud. The intriguing Bubble Nebula lies a mere 11,000 light-years away toward the boastful constellation Cassiopeia.