神秘又美麗的銀河系

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Stellar Nursery 恆星托兒所

This new view shows a stellar nursery called NGC 3324. The intense ultraviolet radiation from several of NGC 3324's hot young stars causes the gas cloud to glow with rich colors and has carved out a cavity in the surrounding gas and dust.

NGC 3324 is located in the southern constellation of Carina (The Keel, part of Jason’s ship the Argo) roughly 7500 light-years from Earth. It is on the northern outskirts of the chaotic environment of the Carina Nebula, which has been sculpted by many other pockets of star formation. A rich deposit of gas and dust in the NGC 3324 region fueled a burst of star birth there several millions of years ago and led to the creation of several hefty and very hot stars that are prominent in the new picture.



As with clouds in the Earth's sky, observers of nebulae can find likenesses within these cosmic clouds. One nickname for the NGC 3324 region is the Gabriela Mistral Nebula, after the Nobel Prize-winning Chilean poet. The edge of the wall of gas and dust at the right bears a strong resemblance to a human face in profile, with the "bump" in the center corresponding to a nose.

Stellar winds and intense radiation from these young stars have blown open a hollow in the surrounding gas and dust. This is most in evidence as the wall of material seen to the center right of this image. The ultraviolet radiation from the hot young stars knocks electrons out of hydrogen atoms, which are then recaptured, leading to a characteristic crimson-colored glow as the electrons cascade through the energy levels, showing the extent of the local diffuse gas. Other colors come from other elements, with the characteristic glow from doubly ionized oxygen making the central parts appear greenish-yellow.

The image was taken using the Wide Field Imager on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile.

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Saturn and Dione 土星和土衛四

Saturn and Dione appear askew in this Cassini spacecraft view, with the north poles rotated to the right, as if they were threaded along on the thin diagonal line of the planet's rings.



This view looks toward the anti-Saturn side of Dione (698 miles, or 1,123 kilometers across). North on Dione is up and rotated 20 degrees to the right. This view looks toward the northern, sunlit side of the rings from less than one degree above the ring plane.

The image was taken in visible green light with the Cassini spacecraft wide-angle camera on Dec. 12, 2011. The view was obtained at a distance of approximately 35,000 miles (57,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 41 degrees.

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Barred Spiral Galaxy 螺旋星系

The NASA/ESA Hubble Space Telescope has taken a picture of the barred spiral galaxy NGC 1073, which is found in the constellation of Cetus (The Sea Monster). Our own galaxy, the Milky Way, is a similar barred spiral, and the study of galaxies such as NGC 1073 helps astronomers learn more about our celestial home.

Most spiral galaxies in the Universe have a bar structure in their center, and Hubble’s image of NGC 1073 offers a particularly clear view of one of these. Galaxies’ star-filled bars are thought to emerge as gravitational density waves funnel gas toward the galactic center, supplying the material to create new stars. The transport of gas can also feed the supermassive black holes that lurk in the centers of almost every galaxy.



Some astronomers have suggested that the formation of a central bar-like structure might signal a spiral galaxy's passage from intense star-formation into adulthood, as the bars turn up more often in galaxies full of older, red stars than younger, blue stars. This storyline would also account for the observation that in the early Universe, only around a fifth of spiral galaxies contained bars, while more than two thirds do in the more modern cosmos.

While Hubble’s image of NGC 1073 is in some respects an archetypal portrait of a barred spiral, there are a couple of quirks worth pointing out.

One, ironically, is almost — but not quite — invisible to optical telescopes like Hubble. In the upper left part of the image, a rough ring-like structure of recent star formation hides a bright source of X-rays. Called IXO 5, this X-ray source is likely to be a binary system featuring a black hole and a star orbiting each other. Comparing X-ray observations from the Chandra spacecraft with this Hubble image, astronomers have narrowed the position of IXO 5 down to one of two faint stars visible here. However, X-ray observations with current instruments are not precise enough to conclusively determine which of the two it is.

Hubble’s image does not only tell us about a galaxy in our own cosmic neighborhood, however. We can also discern glimpses of objects much further away, whose light tells us about earlier eras in cosmic history.

Right across Hubble’s field of view, more distant galaxies are peering through NGC 1073, with several reddish examples appearing clearly in the top left part of the frame.

More intriguing still, three of the bright points of light in this image are neither foreground stars from the Milky Way, nor even distant stars in NGC 1073. In fact they are not stars at all. They are quasars, incredibly bright sources of light caused by matter heating up and falling into supermassive black holes in galaxies literally billions of light-years from us. The chance alignment through NGC 1073, and their incredible brightness, might make them look like they are part of the galaxy, but they are in fact some of the most distant objects observable in the Universe.

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Saturn's Rings and Enceladus 土星的光環和土衛二

A crescent Enceladus appears with Saturn's rings in this Cassini view of the moon.

The famed jets of water ice emanating from the south polar region of the moon are faintly visible here. They appear as a small white blur below the dark south pole, down and to the right of the illuminated part of the moon's surface in the image. The image was contrast enhanced to enhance the visibility of the jets.



Lit terrain seen here is on the trailing hemisphere of Enceladus (313 miles, 504 kilometers across). North on Enceladus is up.

This view looks toward the northern, sunlit side of the rings from just above the ring plane.
The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Jan. 4, 2012. The view was obtained at a distance of approximately 181,000 miles (291,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 136 degrees. Image scale is 1 mile (2 kilometers) per pixel.

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Solar X-Flare 太陽X-火炬

On Jan. 27, 2012, a large X-class flare erupted from an active region near the solar west limb. X-class flares are the most powerful of all solar events. Seen here is an image of the flare captured by the X-ray telescope on Hinode. This image shows an emission from plasma heated to greater than eight million degrees during the energy release process of the flare.

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Ancient Martian Ocean 古老的火星海洋

New results from the MARSIS radar on Mars Express give strong evidence for a former ocean of Mars. The radar detected sediments reminiscent of an ocean floor inside previously identified, ancient shorelines on the red planet. The ocean would have covered the northern plains billions of years ago.
The MARSIS radar was deployed in 2005 and has been collecting data ever since. Jérémie Mouginot, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG) and the University of California, Irvine, and colleagues have analyzed more than two years of data and found that the northern plains are covered in low-density material.



"We interpret these as sedimentary deposits, maybe ice-rich," says Dr Mouginot. "It is a strong new indication that there was once an ocean here."

The existence of oceans on ancient Mars has been suspected before and features reminiscent of shorelines have been tentatively identified in images from various spacecraft. But it remains a controversial issue.

Two oceans have been proposed: 4 billion years ago, when warmer conditions prevailed, and also 3 billion years ago when subsurface ice melted, possibly as a result of enhanced geothermal activity, creating outflow channels that drained the water into areas of low elevation.

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Rover From Space 從太空來的流浪者

This is a picture of the Spirit Lander at Bonneville Crater in color. Near the lower left corner of this view is the three-petal lander platform that NASA's Mars Exploration Rover Spirit drove off in January 2004. The lander is still bright, but with a reddish color, probably due to accumulation of Martian dust.



The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter recorded this view on Jan. 29, 2012, providing the first image from orbit to show Spirit's lander platform in color. The view covers an area about 2,000 feet (about 600 meters) wide, dominated by Bonneveille Crater. North is up. A bright spot on the northern edge of Bonneville Crater is a remnant of Spirit's heat shield.

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Oldest Supernova 最古老的超新星

This image combines data from four space telescopes to create a multi-wavelength view of all that remains of RCW 86, the oldest documented example of a supernova. Chinese astronomers witnessed the event in 185 A.D., documenting a mysterious "guest star" that remained in the sky for eight months. X-ray images from NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory were combined to form the blue and green colors in the image. The X-rays show the interstellar gas that has been heated to millions of degrees by the passage of the shock wave from the supernova.



Infrared data from NASA's Spitzer Space Telescope and WISE, Wide-Field Infrared Survey Explorer, shown in yellow and red, reveal dust radiating at a temperature of several hundred degrees below zero, warm by comparison to normal dust in our Milky Way galaxy.

By studying the X-ray and infrared data, astronomers were able to determine that the cause of the explosion was a Type Ia supernova, in which an otherwise-stable white dwarf, or dead star, was pushed beyond the brink of stability when a companion star dumped material onto it. Furthermore, scientists used the data to solve another mystery surrounding the remnant -- how it got to be so large in such a short amount of time. By blowing away wind prior to exploding, the white dwarf was able to clear out a huge "cavity," a region of very low-density surrounding the system. The explosion into this cavity was able to expand much faster than it otherwise would have.

This is the first time that this type of cavity has been seen around a white dwarf system prior to explosion. Scientists say the results may have significant implications for theories of white-dwarf binary systems and Type Ia supernovae.

RCW 86 is approximately 8,000 light-years away. At about 85 light-years in diameter, it occupies a region of the sky in the southern constellation of Circinus that is slightly larger than the full moon. This image was compiled in October 2011.

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Planck Microwaves 普朗克微波

ESA’s Planck mission has revealed that our galaxy contains previously undiscovered islands of cold gas and a mysterious haze of microwaves. These results give scientists new treasure to mine and take them closer to revealing the blueprint of cosmic structure.

The new results are being presented this week at an international conference in Bologna, Italy, where astronomers from around the world are discussing the mission’s intermediate results. These results include the first map of carbon monoxide to cover the entire sky. Carbon monoxide is a constituent of the cold clouds that populate the Milky Way and other galaxies. Predominantly made of hydrogen molecules, these clouds provide the reservoirs from which stars are born.



However, hydrogen molecules are difficult to detect because they do not readily emit radiation. Carbon monoxide forms under similar conditions and, even though it is much rarer, it emits light more readily and therefore is more easily detectable. So, astronomers use it to trace the clouds of hydrogen.

“Planck turns out to be an excellent detector of carbon monoxide across the entire sky,” says Planck collaborator Jonathan Aumont from the Institut d’Astrophysique Spatiale, Universite Paris XI, Orsay, France.

Surveys of carbon monoxide undertaken with radio telescopes on the ground are extremely time consuming, hence they are limited to portions of the sky where molecular clouds are already known or expected to exist.

“The great advantage of Planck is that it scans the whole sky, allowing us to detect concentrations of molecular gas where we didn’t expect to find them,” says Dr. Aumont.

Planck has also detected a mysterious haze of microwaves that presently defies explanation.It comes from the region surrounding the galactic center and looks like a form of energy called synchrotron emission. This is produced when electrons pass through magnetic fields after having been accelerated by supernova explosions.

The curiosity is that the synchrotron emission associated with the galactic haze exhibits different characteristics from the synchrotron emission seen elsewhere in the Milky Way. The galactic haze shows what astronomers call a ‘harder’ spectrum: its emission does not decline as rapidly with increasing energies.

Several explanations have been proposed for this unusual behavior, including higher supernova rates, galactic winds and even the annihilation of dark-matter particles. So far, none of them has been confirmed and it remains puzzling.

“The results achieved thus far by Planck on the galactic haze and on the carbon monoxide distribution provide us with a fresh view on some interesting processes taking place in our galaxy,” says Jan Tauber, ESA’s Project Scientist for Planck.

Planck’s primary goal is to observe the Cosmic Microwave Background (CMB), the relic radiation from the Big Bang, and to measure its encoded information about the constituents of the Universe and the origin of cosmic structure.

But it can only be reached once all sources of foreground emission, such as the galactic haze and the carbon monoxide signals, have been identified and removed.

“The lengthy and delicate task of foreground removal provides us with prime datasets that are shedding new light on hot topics in galactic and extragalactic astronomy alike,” says Dr. Tauber. “We look forward to characterizing all foregrounds and then being able to reveal the CMB in unprecedented detail.”

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Titan and Rhea 土衛六和瑞亞

Craters appear well defined on icy Rhea in front of the hazy orb of the much larger moon Titan in this Cassini spacecraft view of these two Saturn moons.

Lit terrain seen here is on the leading hemispheres of Rhea and Titan. North on the moons is up and rotated 13 degrees to the left. The limb, or edge of the visible disk, of Rhea is slightly overexposed in this view.



The image was taken in visible green light with the Cassini spacecraft narrow-angle camera on Dec. 10, 2011. The view was acquired at a distance of approximately 1.2 million miles (2 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 109 degrees. The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 109 degrees. Image scale is 8 miles (12 kilometers) per pixel on Titan and 5 miles (8 kilometers) per pixel on Rhea.

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Auroras Over the Midwest 在中西部之極光

In this image taken on Jan. 25, 2012, the Aurora Borealis steals the scene in this nighttime photograph shot from the International Space Station as the orbital outpost flew over the Midwest. The spacecraft was above south central Nebraska when the photo was taken. The image, taken at an oblique angle, looks north to northeast.

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Supernova Remnant 超新星遺跡

Using NASA’s Hubble Space Telescope, astronomers have solved a longstanding mystery on the type of star, or so-called progenitor, which caused a supernova seen in a nearby galaxy. The finding yields new observational data for pinpointing one of several scenarios that trigger such outbursts.

Based on previous observations from ground-based telescopes, astronomers knew the supernova class, called a Type Ia, created a remnant named SNR 0509-67.5, which lies 170,000 light-years away in the Large Magellanic Cloud galaxy.



Theoretically, this kind of supernova explosion is caused by a star spilling material onto a white dwarf companion, the compact remnant of a normal star, until it sets off one of the most powerful explosions in the universe.

Astronomers failed to find any remnant of the companion star, however, and concluded that the common scenario did not apply in this case, although it is still a viable theory for other Type Ia supernovae.

“We know Hubble has the sensitivity necessary to detect the faintest white dwarf remnants that could have caused such explosions,” said lead investigator Bradley Schaefer of Louisiana State University (LSU) in Baton Rouge. “The logic here is the same as the famous quote from Sherlock Holmes: ‘when you have eliminated the impossible, whatever remains, however improbable, must be the truth.’”

The cause of SNR 0509-67.5 can be explained best by two tightly orbiting white dwarf stars spiraling closer and closer until they collided and exploded.

For four decades, the search for Type Ia supernovae progenitors has been a key question in astrophysics. The problem has taken on special importance during the last decade with Type Ia supernovae being the premier tools for measuring the accelerating universe
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Type Ia supernovae release tremendous energy, in which the light produced is often brighter than an entire galaxy of stars. The problem has been to identify the type of star system that pushes the white dwarf’s mass over the edge and triggers this type of explosion. Many possibilities have been suggested, but most require that a companion star near the exploding white dwarf be left behind after the explosion.

Therefore, a possible way to distinguish between the various progenitor models has been to look deep in the center of an old supernova remnant to search for the ex-companion star.

In 2010, Schaefer and Ashley Pagnotta of LSU were preparing a proposal to look for any faint ex-companion stars in the center of four supernova remnants in the Large Magellanic Cloud when they discovered the Hubble Space Telescope already had taken the desired image of one of their target remnants, SNR 0509-67.5, for the Hubble Heritage program, which collects images of especially photogenic astronomical targets.

In analyzing the central region, they found it to be completely empty of stars down to the limit of the faintest objects Hubble can detect in the photos. Schaefer suggests the best explanation left is the so-called “double degenerate model” in which two white dwarfs collide.

The results are being reported today at the meeting of the American Astronomical Society in Austin, Texas. A paper on the results was published in the Jan. 12, 2012 issue of the journal Nature.
There are no recorded observations of the star exploding. However, researchers at the Space Telescope Science Institute in Baltimore, Md. have identified light from the supernova that was reflected off of interstellar dust, delaying its arrival at Earth by 400 years. This delay, called a light echo of the supernova explosion also allowed the astronomers to measure the spectral signature of the light from the explosion. By virtue of the color signature, astronomers were able to deduce it was a Type Ia supernova.

Because the remnant appears as a nice symmetric shell or bubble, the geometric center can be determined accurately. These properties make SNR 0509-67.5 an ideal target to search for ex-companions. The young age also means that any surviving stars have not moved far from the site of the explosion.

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Fastest Black Hole Wind 最快的黑洞風

This artist's impression shows a binary system containing a stellar-mass black hole called IGR J17091-3624, or IGR J17091 for short. The strong gravity of the black hole, on the left, is pulling gas away from a companion star on the right. This gas forms a disk of hot gas around the black hole, and the wind is driven off this disk.



New observations with NASA's Chandra X-ray Observatory clocked the fastest wind ever seen blowing off a disk around this stellar-mass black hole. Stellar-mass black holes are born when extremely massive stars collapse and typically weigh between five and 10 times the mass of the Sun.

The record-breaking wind is moving about twenty million miles per hour, or about three percent the speed of light. This is nearly ten times faster than had ever been seen from a stellar-mass black hole, and matches some of the fastest winds generated by supermassive black holes, objects millions or billions of times more massive.

Another unanticipated finding is that the wind, which comes from a disk of gas surrounding the black hole, may be carrying away much more material than the black hole is capturing.

The high speed for the wind was estimated from a spectrum made by Chandra in 2011. A spectrum shows how intense the X-rays are at different energies. Ions emit and absorb distinct features in spectra, which allow scientists to monitor them and their behavior. A Chandra spectrum of iron ions made two months earlier showed no evidence of the high-speed wind, meaning the wind likely turns on and off over time.

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Mackenzie Bay Breakup 麥肯齊灣

Off the northeastern edge of Antarctica’s Amery Ice Shelf lies Mackenzie Bay, which was painted with a ghostly blue-green mass in early February 2012. Similarly colored tendrils also streamed northward across the ocean, their flow sometimes interrupted by icebergs.

Multiple factors might account for the ghostly shapes, including low-lying clouds or katabatic winds—downslope winds blowing toward the coast, which can freeze the water at the ocean surface. But an intriguing and perhaps more likely explanation involves processes occurring below the ice shelf.



An ice shelf is a thick slab of ice often fed by glaciers attached to the coastline. The shelf floats on the ocean surface, with seawater circulating underneath. Like most ice shelves, the Amery is very thick in the upstream area near the shore. It thins significantly as it stretches northward away from the continent.

Water at depth is subject to much greater pressure than water at the surface, and one effect of this intense pressure is that it effectively lowers the freezing point. So water circulating at depth beneath the Amery Ice Shelf may be slightly below the temperature at which it would normally begin to freeze. As some that water wells up along the underbelly of the shelf, the pressure is reduced and the water begins to freeze even though the temperature may not change.

As it freezes, this deep-ocean water forms needle-like crystals known as frazil. The crystals are only 3 to 4 millimeters (0.12 to 0.16 inches) wide, but a sufficient concentration of frazil can change the appearance of the water. A frazil-rich plume probably accounts for the blue-green waters off the Amery Ice Shelf in the image above. Modeling of ocean circulation beneath the shelf indicates just such a plume emerging in that location.

Frazil-rich water explains the plume, and wind transport of the surface water explains the long streams extending northward. As the sub-iceshelf water mixes with surface water around the Antarctic coastline, the frazil is gradually melted and the streams disappear.

The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image of Mackenzie Bay and the ice shelf on February 12, 2012.

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Watch Out for Wampas 小心魔鬼

These barchan (crescent-shaped) sand dunes are found within the North Polar erg of Mars. This type of dune provides a great record of the wind environment when they formed and moved: barchan dunes' horns point downwind. Although the question of present-day sand motion is still open, it appears possible that these dunes are active (when not covered in frost) as their crestlines are very sharp and their slipfaces (the inner curved region between the horns/downwind surface) appears very smooth and steep.



In this image, taken during the northern spring season, the dunes and ground are still covered in seasonal frost. The speckled appearance is due to the warming of the area -- as the carbon dioxide frost and ice on the dunes warms, small areas warm and sublimate (turn from solid to gas) faster, creating small jets that expose/deposit dark sand and dust onto the surface. Notice that there are no spots on the ground between the dunes -- that is because the ground stays more uniformly cold, unlike the darker dune sand.

As spring continues, more spots will appear on the dunes until, suddenly, all of the frost on the dunes and ground will be gone and the dark dune sand will be exposed until next winter.

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Star Bomb 爆破的星星

NASA's Hubble Telescope captured an image of Eta Carinae. This image consists of ultraviolet and visible light images from the High Resolution Channel of Hubble's Advanced Camera for Surveys. The field of view is approximately 30 arcseconds across.

The larger of the two stars in the Eta Carinae system is a huge and unstable star that is nearing the end of its life, and the event that the 19th century astronomers observed was a stellar near-death experience. Scientists call these outbursts supernova impostor events, because they appear similar to supernovae but stop just short of destroying their star.



Although 19th century astronomers did not have telescopes powerful enough to see the 1843 outburst in detail, its effects can be studied today. The huge clouds of matter thrown out a century and a half ago, known as the Homunculus Nebula, have been a regular target for Hubble since its launch in 1990. This image, taken with the Advanced Camera for Surveys High Resolution Channel, is the most detailed yet, and shows how the material from the star was not thrown out in a uniform manner, but forms a huge dumbbell shape.

Eta Carinae is one of the closest stars to Earth that is likely to explode in a supernova in the relatively near future (though in astronomical timescales the "near future" could still be a million years away). When it does, expect an impressive view from Earth, far brighter still than its last outburst: SN 2006gy, the brightest supernova ever observed, came from a star of the same type, though from a galaxy over 200 million light-years away.

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Eastern U.S. From Space 從太空看到的美國東部

An Expedition 30 crew member aboard the International Space Station took this nighttime photograph of much of the Atlantic coast of the United States. Large metropolitan areas and other easily recognizable sites from the Virginia/Maryland/Washington, D.C. area are visible in the image that spans almost to Rhode Island. Boston is just out of frame at right. Long Island and the New York City area are visible in the lower right quadrant. Philadelphia and Pittsburgh are near the center. Parts of two Russian vehicles parked at the orbital outpost are seen in left foreground.

This image was taken on Feb. 6, 2012.

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Giant Planet and Giant Moon 巨大的行星和巨大的月亮

Saturn's largest moon, Titan, looks small here, pictured to the right of the gas giant in this Cassini spacecraft view.

Titan (3,200 miles, or 5,150 kilometers across) is in the upper right. Saturn's rings appear across the top of the image, and they cast a series of shadows onto the planet across the middle of the image.



The moon Prometheus (53 miles, or 86 kilometers across) appears as a tiny white speck above the rings in the far upper right of the image. The shadow cast by Prometheus can be seen as a small black speck on the planet on the far left of the image, between the shadows cast by the main rings and the thin F ring. The shadow of the moon Pandora also can be seen on the planet south of the shadows of all the rings, below the center of the image towards the right side of the planet. Pandora is not shown here.

This view looks toward the southern, unilluminated side of the rings from about 1 degree below the ringplane.

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Bright Lights, Green City 明亮的燈光 綠色的城市

Two extremely bright stars illuminate a greenish mist in this and other images from the new GLIMPSE360 survey. This fog is comprised of hydrogen and carbon compounds called polycyclic aromatic hydrocarbons (PAHs), which are found right here on Earth in sooty vehicle exhaust and on charred grills. In space, PAHs form in the dark clouds that give rise to stars. These molecules provide astronomers a way to visualize the peripheries of gas clouds and study their structures in great detail. PAHs are not actually "green;" a representative color coding in these images lets scientists observe PAHs glow in the infrared light that Spitzer sees, and which is invisible to us.



Strange streaks - likely dust grains that lined up with magnetic fields - distort the star in the top left. The fairly close, well-studied star GL 490 gleams in the middle right. The new GLIMPSE360 observations have revealed several small blobby outflows of gas from nearby forming stars, which indicate their youth. Such outflows are a great way to target really young, massive stars in their very earliest, hard-to-catch stages.

This image is a combination of data from Spitzer and the Two Micron All Sky Survey (2MASS). The Spitzer data was taken after Spitzer's liquid coolant ran dry in May 2009, marking the beginning of its "warm" mission. Light from Spitzer's remaining infrared channels at 3.6 and 4.5 microns has been represented in green and red, respectively. 2MASS 2.2 micron light is blue.

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Baby Star Sprouting Jets 新生星噴射機

NASA's Spitzer Space Telescope took this image of a baby star sprouting two identical jets (green lines emanating from fuzzy star). The jet on the right had been seen before in visible-light views, but the jet at left -- the identical twin to the first jet -- could only be seen in detail with Spitzer's infrared detectors. The left jet was hidden behind a dark cloud, which Spitzer can see through.



The twin jets, in a system called Herbig-Haro 34, are made of identical knots of gas and dust, ejected one after another from the area around the star. By studying the spacing of these knots, and knowing the speed of the jets from previous studies, astronomers were able to determine that the jet to the right of the star punches its material out 4.5 years later than the counter-jet.

The new data also reveal that the area from which the jets originate is contained within a sphere around the star, with a radius of 3 astronomical units. An astronomical unit is the distance between Earth and the sun. Previous studies estimated that the maximum size of this jet-making zone was 10 times larger.

The wispy material is gas and dust. Arc-shaped bow shocks can be seen at the ends of the twin jets. The shocks consist of compressed material in front of the jets.

The Herbig-Haro 34 jets are located at approximately 1,400 light-years away in the Orion constellation.