科普 神奇的宇宙----图片(每天更新中)

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11 Hour Star Trails

Explanation: Fix your camera to a tripod, lock the shutter open, and you can make an image of star trails - graceful concentric arcs traced by the stars as planet Earth rotates on its axis. Of course, the length of the star trails will depend on the exposure time. While exposures lasting just five minutes produce a significant arc, in about 12 hours a given star would trace out half a circle. But in any long exposure, the background glow from light-polluted skies can build up to wash out the trails. Still, astronomer Josch Hambsch produced this stunning composite of star trails around the South Celestial Pole with an effective "all night" exposure time of almost 11 hours. To do it, he combined 128 consecutive five minute long digital exposures recorded in very dark night skies above Namibia. In his final image, the background glow on the right is due in part to the faint, arcing Milky Way.

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M33: Spiral Galaxy in Triangulum

Explanation: The small, northern constellation Triangulum harbors this magnificent face-on spiral galaxy, M33. Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33 is over 50,000 light-years in diameter, third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and our own Milky Way. About 3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy and astronomers in these two galaxies would likely have spectacular views of each other's grand spiral star systems. As for the view from planet Earth, this detailed, wide field image nicely shows off M33's blue star clusters and pinkish star forming regions which trace the galaxy's loosely wound spiral arms. In fact, the cavernous NGC 604 is the brightest star forming region, seen here at about the 1 o'clock position from the galaxy center. Like M31, M33's population of well-measured variable stars have helped make this nearby spiral a cosmic yardstick for establishing the distance scale of the Universe.

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Star Clusters Young and Old

Explanation: Many stars form in clusters. Galactic or open star clusters are relatively young swarms of bright stars born together near the plane of our Milky Way Galaxy. Separated by about a degree on the sky, two nice examples are M46 (upper left) 5,400 light-years in the distance and M47 (lower right) only 1,600 light-years away toward the nautical constellation Puppis. Around 300 million years young M46 contains a few hundred stars in a region about 30 light-years across. Aged 80 million years, M47 is a smaller but looser cluster of about 50 stars spanning 10 light-years. But this portrait of stellar youth also contains an ancient interloper. The small, colorful patch of glowing gas in M46 is actually the planetary nebula NGC 2438 - the final phase in the life of a sun-like star billions of years old. NGC 2438 is estimated to be only 3,000 light-years distant and likely represents a foreground object, only by chance appearing along our line of sight to youthful M46.

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Messier 110

Explanation: This very sharp telescopic vista features the last object in the modern version of Charles Messier's catalog of bright clusters and nebulae - Messier 110. A dwarf elliptical galaxy, M110 (aka NGC 205) is actually a bright satellite of the large spiral galaxy Andromeda, making M110 a fellow member of the local group of galaxies. Seen through a foreground of nearby stars, M110 is about 15,000 light-years across. That makes it comparable in size to satellite galaxies of our own Milky Way, the Large and Small Magellanic Clouds. Though elliptical galaxies are normally thought to be lacking in gas and dust to form new stars, M110 is known to contain young stars, and faint dust clouds can easily be seen in this detailed image at about the 7 and 11 o'clock positions relative to the galaxy center.

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Bright Cliffs Across Saturn's Moon Dione

Explanation: What causes the bright streaks on Dione? Recent images of this unusual moon by the robot Cassini spacecraft now orbiting Saturn are helping to crack the mystery. Close inspection of Dione's trailing hemisphere, pictured above, indicates that the white wisps are composed of deep ice cliffs dropping hundreds of meters. The cliffs may indicate that Dione has undergone some sort of tectonic surface displacements in its past. The bright ice-cliffs run across some of Dione's many craters, indicating that the process that created them occurred later than the impacts that created those craters. Dione is made of mostly water ice but its relatively high density indicates that it contains much rock inside. Giovanni Cassini discovered Dione in 1684. The above image was taken at the end of July from a distance of about 263,000 kilometers. Other high resolution images of Dione were taken by the passing Voyager spacecraft in 1980.

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The Large Magellanic Cloud in Infrared

Explanation: Where does dust collect in galaxies? To help find out, a team of researchers took the most detailed image ever of gas clouds and dust in the neighboring Large Magellanic Cloud (LMC) galaxy. The composite image, shown above, was taken by the Spitzer Space Telescope in infrared light, which highlights the natural glow of the warm materials returned to the interstellar medium by stars. The above mosaic combines 300,000 individual pointings to create a composite 1,000-times sharper than any previous LMC image. Visible are vast clouds of gas and dust, showing in graphic detail that dust prefers regions near young stars (red-tinted bright clouds), scattered unevenly between the stars (green-tinted clouds), and in shells around old stars (small red dots). Also visible are huge caverns cleared away by the energetic outflows of massive former stars. The faint blue (false-color) glow across the bottom is the combined light from the old stars in the central bar of the LMC. The LMC is a satellite galaxy to our own Milky Way Galaxy, spans about 70,000 light years, and lies about 160,000 light years away toward the southern constellation of the Swordfish (Dorado).

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Dusty Spiral M66

Explanation: When morning twilight came to the Paranal Observatory in Chile, astronomers Mark Neeser and Peter Barthel interrupted their search for faint quasars, billions of light-years away. And just for a moment, they used Very Large Telescopes at the European Southern Observatory to appreciate the beauty of the nearby Universe. One result was this stunning view of beautiful spiral galaxy M66, a mere 35 million light-years away. About 100 thousand light-years across with striking dust lanes and bright star clusters along sweeping spiral arms, M66 is well known to astronomers as a member of the Leo Triplet of galaxies. Gravitational interactions with its neighborhood galaxies have likely influenced the shape of dusty spiral M66.

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Gemini South Star Trails

Explanation: Stars seem to arc through southern skies in this surrealistic time exposure -- recorded before moonrise from the Gemini South Observatory, Cerro Pachon, Chile, Planet Earth. During the one hour 40 minute exposure camera and tripod were fixed, so the concentric star trails are a reflection of Earth's daily rotation about its axis. The view looks to the south and includes the Gemini telescope enclosure in the foreground. At the apparent center of the curving trails, the South Celestial Pole lies just off the upper left edge. Two faint, wide streaks track the Magellanic Clouds, satellites of the Milky Way Galaxy, while a meteor flashes throught the scene just left of the observatory.

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Extra Galaxies

Explanation: Careful inspection of the full field of view for this sharp composite image reveals a surprising number of galaxies both near and far toward the constellation Ursa Major. The most striking is clearly NGC 3718, a warped spiral galaxy found near picture center. NGC 3718's faint spiral arms look twisted and extended, its bright central region crossed by obscuring dust lanes. A mere 150 thousand light-years to the right is another large spiral galaxy, NGC 3729. The two are likely interacting gravitationally, accounting for the peculiar appearance of NGC 3718. While this galaxy pair lies about 52 million light-years away, the remarkable Hickson Group 56 can also be seen clustered just below NGC 3718. Hickson Group 56 consists of five interacting galaxies and lies over 400 million light-years away.

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A Backward Sunspot and the New Solar Cycle

Explanation: Why is sunspot 905 backwards? Perhaps it is a key marker for the beginning of a new magnetic cycle on our Sun. Every 11 years, our Sun goes through a magnetic cycle, at the end of which its overall magnetic orientation is reversed. An 11-year solar cycle has been observed for hundreds of years by noting peaks and valleys in the average number of sunspots. Just now, the Sun is near Solar Minimum, and likely to start a long progression toward the most active time, called Solar Maximum, in about 5.5 years. An indicator that the sun's magnetic field is reversing is the appearance of sunspots with the reverse magnetic polarity than normal. A few weeks ago, one small candidate reverse sunspot was sighted but faded quickly. Now, however, a larger sunspot with negative polarity is being tracked. This sunspot, numbered 905, appears as the unusual white spot in the above magnetic image of the Sun taken with the SOHO spacecraft a few days ago. In the past few days, Sunspot 905 has actually begun to break apart and might also become the source of coronal mass ejections and explosive solar flares. Solar astronomers predict that the coming Solar Maximum will be unusually active.

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Supernova Remnant E0102 from Hubble

Explanation: It's the blue wisp near the bottom that's the remnant of a tremendous recent supernova explosion. The large pink structure looming to the upper right is part of N76, a large star forming region in our neighboring Small Magellanic Cloud (SMC) galaxy. The supernova remnant wisp, with full coordinate name 1E0102.2-7219 and frequently abbreviated as E0102, also lies in the SMC, about 50 light years away from N76. The above image is a composite of several images taken by the Hubble Space Telescope. E0102 is of research interest because we see it as it appeared only 2,000 years after its explosion. Examination of E0102 therefore gives clues about how an enigmatic supernova works and what materials it dispersed into the surrounding interstellar medium.

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Eight Planets and New Solar System Designations

Explanation: How many planets are in the Solar System? This popular question now has a new formal answer according the International Astronomical Union (IAU): eight. Last week, the IAU voted on a new definition for planet and Pluto did not make the cut. Rather, Pluto was re-classified as a dwarf planet and is considered as a prototype for a new category of trans-Neptunian objects. The eight planets now recognized by the IAU are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Solar System objects now classified as dwarf planets are: Ceres, Pluto, and the currently unnamed 2003 UB313. Planets, by the new IAU definition, must be in orbit around the sun, be nearly spherical, and must have cleared the neighborhood around their orbits. The demotion of Pluto to dwarf planet status is a source of continuing dissent and controversy in the astronomical community.

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Barred Spiral Galaxy NGC 1300

Explanation: Big, beautiful, barred spiral galaxy NGC 1300 lies some 70 million light-years away on the banks of the constellation Eridanus. This Hubble Space Telescope composite view of the gorgeous island universe is one of the largest Hubble images ever made of a complete galaxy. NGC 1300 spans over 100,000 light-years and the Hubble image reveals striking details of the galaxy's dominant central bar and majestic spiral arms. In fact, on close inspection the nucleus of this classic barred spiral itself shows a remarkable region of spiral structure about 3,000 light-years across. Unlike other spiral galaxies, including our own Milky Way, NGC 1300 is not presently known to have a massive central black hole.

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Blue Lagoon

Explanation: Stars come and go as you slide your cursor over this engaging image of M8, aka the Lagoon Nebula. Of course, the nebula is itself a star-forming region, but the stars that appear and disappear here include background and foreground stars that by chance lie along the same line of sight. In this "for fun" comparison of two nearly identical digital images, the stellar point sources were removed from one image by computer processing to leave only the diffuse emission from the glowing gas clouds. In both pictures, red emission (H-alpha emission) from atomic hydrogen dominates the cosmic lagoon's visible light, but narrow band filters were used to record the image data and map the hydrogen emission to green hues, with emission from sulfur atoms in red and oxygen in blue. The lovely Lagoon Nebula spans about 30 light-years at an estimated distance of 5,000 light-years toward the constellation Sagittarius.

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The Matter of the Bullet Cluster

Explanation: The matter in galaxy cluster 1E 0657-56, fondly known as the "bullet cluster", is shown in this composite image. A mere 3.4 billion light-years away, the bullet cluster's individual galaxies are seen in the optical image data, but their total mass adds up to far less than the mass of the cluster's two clouds of hot x-ray emitting gas shown in red. Representing even more mass than the optical galaxies and x-ray gas combined, the blue hues show the distribution of dark matter in the cluster. Otherwise invisible to telescopic views, the dark matter was mapped by observations of gravitational lensing of background galaxies. In a text book example of a shock front, the bullet-shaped cloud of gas at the right was distorted during the titanic collision between two galaxy clusters that created the larger bullet cluster itself. But the dark matter present has not interacted with the cluster gas except by gravity. The clear separation of dark matter and gas clouds is considered direct evidence that dark matter exists.

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A Map of Asteroid Vesta

Explanation: Vesta is a huge rock 500 kilometers across that orbits out past Mars. In 1997, the above map of Vesta created using the Hubble Space Telescope was released showing a rugged surface highlighted by a single crater spanning nearly the entire length of the asteroid. The large crater dominates the lower part of the above false-color conglomerate image: blue indicates low terrain, while red indicates raised terrain. Evidence indicates that Vesta underwent a tremendous splintering collision about a billion years ago. In October 1960, a small chunk of this rock believed to have originated on Vesta fell to Earth and was recovered in Australia. Vesta is considered by some to be a candidate for reclassification into a planet.

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Spitzer's Orion

Explanation: Few cosmic vistas excite the imagination like the Orion Nebula, an immense stellar nursery some 1,500 light-years away. Also known as M42, the nebula is visible to the unaided eye, but this stunning infrared view from the Spitzer Space Telescope penetrates the turbulent cosmic gas and dust clouds to explore the region in unprecedented detail. At full resolution, the remarkable image data yields a census of new stars and potential solar systems. About 2,300 young stars surrounded by planet-forming disks were detected based on the infrared glow of their warm dust, along with about 200 stellar embryos, stars too young to have developed disks. This 0.8 by 1.4 degree false-color image is about 20 light-years wide at the distance of the Orion Nebula.

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Comet Dust over Colorado

Explanation: The rock formation in the foreground of this night view was recorded on August 10, illuminated by light from a waning gibbous Moon. Even though the sky above also scatters the bright moonlight, a brilliant meteor was captured as it flashed across the scene during the 30 second long exposure. Of course, the meteor was part of the annual rain of dust from periodic Comet Swift-Tuttle known as the Perseid Meteor Shower. Leaving trails that point back to a radiant in the constellation Perseus, the ancient dust particles are vaporized as they enter the atmosphere at about 60 kilometers per second, their visible streaks beginning at altitudes of around 100 kilometers. And though it looks like the knuckles of a giant hand, the curious rock formation can be found in Colorado National Monument park, USA, planet Earth.

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The North America and Pelican Nebulas

Explanation: Here are some familiar shapes in unfamiliar locations. This emission nebula on the left is famous partly because it resembles Earth's continent of North America. To the right of the North America Nebula, cataloged as NGC 7000, is a less luminous nebula that resembles a pelican dubbed the Pelican Nebula. The two emission nebula measure about 50 light-years across, are located about 1500 light-years away, and are separated by a dark absorption cloud. This spectacular image captures, in false color, the nebulas, bright ionization fronts, and fine details of the dark dust. The nebulae can be seen with binoculars from a dark location. Look for a small nebular patch north-east of bright star Deneb in the constellation of Cygnus. It is still unknown which star or stars ionize the red-glowing hydrogen gas.

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IC 410 and NGC 1893

Explanation: A faint, dusty rose of the northern sky, emission nebula IC 410 lies about 12,000 light-years away in the constellation Auriga. The cloud of glowing hydrogen gas is over 100 light-years across, sculpted by stellar winds and radiation from embedded open star cluster NGC 1893. Formed in the interstellar cloud a mere 4 million years ago, bright cluster stars are seen just below the prominent dark dust cloud near picture center. Notable near the 7 o'clock position in this wide, detailed view are two relatively dense streamers of material trailing away from the nebula's central regions. Potentially sites of ongoing star formation, these cosmic tadpole shapes are about 10 light-years long.