Billions of years from now, only one of these two galaxies will remain

Explanation: Billions of years from now, only one of these two galaxies will remain. Until then, spiral galaxies NGC 2207 and IC 2163 will slowly pull each other apart, creating tides of matter, sheets of shocked gas, lanes of dark dust, bursts of star formation, and streams of cast-away stars. Astronomers predict that NGC 2207, the larger galaxy on the left, will eventually incorporate IC 2163, the smaller galaxy on the right. In the most recent encounter that about peaked 40 million years ago, the smaller galaxy is swinging around counter-clockwise, and is now slightly behind the larger galaxy. The space between stars is so vast that when galaxies collide, the stars in them usually do not collide.

Double Cluster in Perseus.

Explanation: This lovely starfield spans some seven full moons (about 3.5 degrees) across the heroic northern constellation of Perseus. Just right of center it holds the famous pair of open or galactic star clusters, h and Chi Persei. Also cataloged as NGC 869 (right) and NGC 884, both clusters are about 7,000 light-years away and contain stars much younger and hotter than the Sun. Separated by only a few hundred light-years, the clusters are both 13 million years young based on the ages of their individual stars, evidence that they were likely a product of the same star-forming region. Always a rewarding sight in binoculars, the Double Cluster is even visible to the unaided eye from dark locations. Not seen in binoculars though, and not often depicted in telescopic images of the region are faint clouds of reddish ionized hydrogen gas found throughout this remarkable cosmic skyscape. A color composite, the image includes narrowband data to enhance emission from the hydrogen clouds. Visible toward the upper left of the wide field of view is another, smaller open star cluster, NGC 957, also of similar age, distance, and possibly related to the more famous Double Cluster in Perseus.

Bright galaxy M82

Explanation: Astronomers really don't find supernovae by looking for the arrows. But in this image taken January 23rd, an arrow does point to an exciting, new supernova, now cataloged as SN 2014J, in nearby bright galaxy M82. Located near the Big Dipper in planet Earth's sky, M82 is also known as the Cigar Galaxy, a popular target for telescopes in the northern hemisphere. In fact, SN 2014J was first spotted as an unfamiliar source in the otherwise familiar galaxy by teaching fellow Steve Fossey and astronomy workshop students Ben Cooke, Tom Wright, Matthew Wilde and Guy Pollack at the University College London Observatory on the evening of January 21. M82 is a mere 12 million light-years away (so the supernova explosion did happen 12 million years ago, that light just now reaching Earth), making supernova SN 2014J one of the closest to be seen in recent decades. Spectra indicate it is a Type Ia supernova caused by the explosion of a white dwarf accreting matter from a companion star. By some estimates two weeks away from its maximum brightness, SN 2014J is already the brightest part of M82 and visible in small telescopes in the evening sky.

It was a quiet day on the Sun

Explanation: It was a quiet day on the Sun. The above image shows, however, that even during off days the Sun's surface is a busy place. Shown in ultraviolet light, the relatively cool dark regions have temperatures of thousands of degrees Celsius. Large sunspot group AR 9169 from the last solar cycle is visible as the bright area near the horizon. The bright glowing gas flowing around the sunspots has a temperature of over one million degrees Celsius. The reason for the high temperatures is unknown but thought to be related to the rapidly changing magnetic field loops that channel solar plasma. Large sunspot group AR 9169 moved across the Sun during 2000 September and decayed in a few weeks.

Debris from a rockslide

The first sign of trouble for residents along the upper Seti River in Nepal was the water. In late April and early May 2012, what was usually a roaring river had slowed to a trickle. And the milky-white water—colored by rock flour from glaciers upstream in the Sabche Cirque—had turned blue and clear.

Residents regarded the river changes as bizarre, but nobody connected the slowdown to anything dangerous upstream. So it came as a surprise when a slurry of sediment, rock, and water suddenly surged through the valley on May 5, 2012, obliterating dozens of homes and sweeping 72 people to their deaths. In the chaotic aftermath of the flood, questions swirled about where the water had come from and how it had arrived with so little warning.

Had a natural dam formed and then abruptly burst? Had debris from a rockslide dammed the Seti into a glacial lake and then failed? Had water long trapped in subterranean caves found its way out? Did an avalanche high on Annapurna triggered the deluge? “There were all sorts of theories in the beginning, but they were mostly speculation,” said Jeffrey Kargel, a University of Arizona hydrologist who has been studying the disaster. “We didn’t have hard data from the field that could prove or disprove most of them.”

Now they have that data. Twenty months after the disaster, experts like Kargel have made enough observations in the field, conducted enough tests in the lab, and analyzed enough satellite data to say quite definitely what happened. He has concluded that it was not just one event but a series of them that combined to produce the devastation.

It began weeks before the flood with a series of rockfalls that sent debris tumbling into the Seti River, backing water up in the extremely deep and narrow gorge. The last of these landslides occurred just a week or so before the flood. The situation grew dire on May 5, 2012, when an unusually powerful ice avalanche and rockfall tumbled down a vertical cliff on a ridge just south of Annapurna IV. The total drop from the Annapurna IV ridgeline to the bed of the Seti is about 6,100 meters (20,000 feet) spread over a distance of only 40 kilometers (25 miles)—more relief than anywhere in the continental United States.

“You can imagine what an enormous amount of force accompanied the avalanche,” said Kargel. “It was so powerful that huge amounts of snow melted due to the friction, and it produced a blast of hurricane-force winds that flattened old-growth forests near the Seti River Gorge.” As the force of the avalanche and winds poured into the gorge, it overwhelmed the natural dam created by the earlier rockslides. The dam burst and sent a surge of pent up water and avalanche debris rushing downstream.

Evidence of the massive rockfall and avalanche was still visible on December 22, 2013, when an astronaut on the International Space Station snapped a photograph (top) showing debris still coating the slopes below Annapurna IV. Next to the snow-covered slopes of the cirque, the debris-covered surfaces appear tan. The second image, a photograph by Kargel, shows the vertical cliff where the avalanche began.

Kargel’s research group has taken four separate trips to the area since 2012. In the process of piecing together how the disaster occurred, the team also analyzed whether a similar event could 

Kilauea’s caldera

If you were to rank all of the volcanoes in the world in terms of activity, Kilauea would come out near the top. The volcano is so given to eruptions that it is said to be home to Pele, the temperamental Hawaiian volcano goddess. The most recent eruption began pouring from Kilauea’s east rift into the Pacific Ocean in 1983 and had not ceased as of December 8, 2005. Though no more than a lump on the eastern flanks of the massive Mauna Loa volcano on the Island of Hawaii, Kilauea has been prodigiously more productive than its neighbor. As much as ninety percent of Kilauea’s surface is less than 1,100 years old.

This Ikonos image, taken on January 14, 2003, shows Kilauea’s summit caldera, the surface of which is covered in fresh lava flows. The newer flows are dark, while the older flows pale as the iron in the lava oxidizes into rust. The oldest flow in the caldera is from 1882. The Halema`uma`u crater forms a pale circle in the southwest section of the caldera. As recently as 1924, the crater was filled with a molten lava lake. According to the Hawaiian Volcano Observatory (visible in the upper left corner of the image), the name comes from Polynesian mythology. “Halema`uma`u” refers to a house of ferns that Kamapua`a, a suitor of Pele, built over the crater to keep her from escaping. As the fresh flows in the image testify, the attempt was not successful. The other crater seen in the image, Keanakako`i, was the site of an eruption in 1974. In the upper right corner of the image is Volcano House, a private hotel.

Volcanoes on the island of Hawai`i.

Snow caps the summits of Mauna Loa (center) and Mauna Kea (toward the top, center) volcanoes on the island of Hawai`i. With its summit standing roughly 17 km (56,000 feet) above its base and its flanks covering about half of the Island of Hawai`i, Mauna Loa is the world?s largest volcano. According to the U.S. Geological Survey, Mauna Loa?s peak rises roughly 4 km above sea level, its flanks slope downward another 5 km to the ocean floor, and then it is so massive it compresses the sea floor another 8 km!

Meanwhile, toward the island?s southeastern shore, the ongoing eruption of Kilauea continues. The red boxes indicate the location of the lava flow from the volcano?s Pu`u `O`o cone, which has been erupting since 1983.

Hawaii

If anyone has an easy job, it’s the Hawaii tourism authority, the organization responsible for promoting the island as a tourist destination. Using language such as “lush rain forests” and “black sand beaches,” they sum up the Island of Hawaii as a “vast canvas of environments.”

The words are the perfect description for the top image, captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on January 26, 2014. The remarkably cloud-free view shows the range of ecological diversity present on the island. The lower image, an astronaut photograph, shows the island in context. At 10,432 square kilometers (4,028 square miles), the Island of Hawaii is nearly twice as big as all of the other islands combined.

Many of the world’s climate zones can be found on Hawaii for two related reasons: rainfall and altitude. The Big Island is home to Mauna Kea, the tallest sea mountain in the world at 4,205 meters (13,796 feet) and the tallest mountain on the planet—if you measure from seafloor to summit, a distance of more than 9,800 meters (32,000 feet).

Despite Mauna Kea’s height, it is Mauna Loa that dominates the island. With an altitude of about 4,169 meters (13,678 feet)—the actual number varies depending on volcanic activity—Mauna Loa is the most massive mountain in the world. Temperatures dip low at the summit of these peaks, resulting in a tree-free polar tundra, pale brown in this image.

The mountains help shape rainfall patterns on Hawaii so that desert landscapes exist side-by-side with rainforests. In fact, average yearly rainfall ranges from 204 millimeters (8 inches) to 10,271 mm (404 inches). Trade winds blow mostly from the east-northeast, and the sea-level breezes hit the mountains and get forced up, forming rainclouds. The east side of the island is lush and green with tropical rainforest. Much less moisture makes it to the lee side of the mountains. The northwestern shores of Hawaii are desert. Kona, on the western shore, receives plenty of rain because the trade winds curve back around the mountains and bring rain. Pale green areas on all sides of the island are agricultural land and grassland.

The other environmental force painting Hawaii’s canvas is volcanism. Mauna Loa and Mauna Kea are both volcanic, though only Mauna Loa has been active recently. However, in this department, Kilauea is the superlative: It is one of the world’s most active volcanoes. A small puff of steam rises from an erupting vent in this image. Black and dark brown lava flows extend from both Kilauea and Mauna Loa.

Interested in other sunny island destinations? Be sure to visit the Earth Observatory’s latest image gallery, Islands in the Sun.

Milky Way Galaxy

Explanation: There is a road that connects the Northern to the Southern Cross but you have to be at the right place and time to see it. The road, as pictured above, is actually the central band of our Milky Way Galaxy; the right place, in this case, is dark Laguna Cejar in Salar de Atacama of Northern Chile; and the right time was in early October, just after sunset. Many sky wonders were captured then, including the bright Moon, inside the Milky Way arch; Venus, just above the Moon; Saturn and Mercury, just below the Moon; the Large and Small Magellanic Clouds satellite galaxies, on the far left; red airglow near the horizon on the image left; and the lights of small towns at several locations across the horizon. One might guess that composing this 30-image panorama would have been a serene experience, but for that one would have required earplugs to ignore the continued brays of wild donkeys.

M83 is one of the closest and brightest spiral galaxies on the sky.

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 by the Hubble Space Telescope in a recently released image, 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 of M83.

A magnetic filament of solar material erupted on the sun

A magnetic filament of solar material erupted on the sun in late September, breaking the quiet conditions in a spectacular fashion. The 200,000 mile long filament ripped through the sun's atmosphere, the corona, leaving behind what looks like a canyon of fire. The glowing canyon traces the channel where magnetic fields held the filament aloft before the explosion. In reality, the sun is not made of fire, but of something called plasma: particles so hot that their electrons have boiled off, creating a charged gas that is interwoven with magnetic fields.

What's happening in the sky?

What's happening in the sky? On this cold winter night in Iceland, quite a lot. First, in the foreground, lies the largest glacier in Iceland: Vatnajokull. On the far left, bright green auroras appear to emanate from the glacier as if it was a volcano. Aurora light is reflected by the foreground lake Jökulsárlón. On the far right is a long and unusual lenticular cloud tinged with green light emitted from another aurora well behind it. Just above this lenticular cloud are unusual iridescent lenticular clouds displaying a broad spectral range of colors. Far beyond the lenticular is the setting Moon, while far beyond even the Moon are setting stars. The above image was captured in late March of 2012

Spiral galaxy NGC 1097

Enigmatic spiral galaxy NGC 1097 shines in southern skies, about 45 million light-years away in the chemical constellation Fornax. Its blue spiral arms are mottled with pinkish star forming regions in this colorful galaxy portrait. They seem to have wrapped around a small companion galaxy below and left of center, about 40,000 light-years from the spiral's luminous core. That's not NGC 1097's most peculiar feature, though. The very deep exposure hints of faint, mysterious jets, most easily seen to extend well beyond the bluish arms toward the lower right. In fact, four faint jets are ultimately recognized in optical images of NGC 1097. The jets trace an X centered on the galaxy's nucleus, but probably don't originate there. Instead, they could be fossil star streams, trails left over from the capture and disruption of a much smaller galaxy in the large spiral's ancient past. A Seyfert galaxy, NGC 1097's nucleus also harbors a supermassive black hole.

The flash spectrum of the Sun.

In a flash, the visible spectrum of the Sun changed from absorption to emission on November 3rd, during the brief total phase of a solar eclipse. That fleeting moment is captured by telephoto lens and diffraction grating in this well-timed image from clearing skies over Gabon in equatorial Africa. With overwhelming light from the Sun's disk blocked by the Moon, the normally dominant absorption spectrum of the solar photosphere is hidden. What remains, spread by the diffraction grating into the spectrum of colors to the right of the eclipsed Sun, are individual eclipse images at each wavelength of light emitted by atoms along the thin arc of the solar chromosphere. The brightest images, or strongest chromospheric emission lines, are due to Hydrogen atoms that produce the red hydrogen alpha emission at the far right and blue hydrogen beta emission to the left. In between, the bright yellow emission image is caused by atoms of Helium, an element only first discovered in .

the flash spectrum of the Sun

Tutulemma: Solar Eclipse Analemma

Explanation: If you went outside at exactly the same time every day and took a picture that included the Sun, how would the Sun's position change? With great planning and effort, such a series of images can be taken. The figure-8 path the Sun follows over the course of a year is called an analemma. Yesterday, the Winter Solstice day in Earth's northern hemisphere, the Sun appeared at the bottom of the analemma. Analemmas created from different latitudes would appear at least slightly different, as well as analemmas created at a different time each day. With even greater planning and effort, the series can include a total eclipse of the Sun as one of the images. Pictured is such a total solar eclipse analemma or Tutulemma - a term coined by the photographers based on the Turkish word for eclipse. The above composite image sequence was recorded from Turkey starting in 2005. The base image for the sequence is from the total phase of a solar eclipse as viewed from Side, Turkey on 2006 March 29. Venus was also visible during totality, toward the lower right.

Geminid Meteors over Chile

 From a radiant point in the constellation of the Twins, the annual Geminid meteor shower rained down on planet Earth over the past few weeks. Recorded near the shower's peak over the night of December 13 and 14, the above skyscape captures Gemini's shooting stars in a four-hour composite from the dark skies of the Las Campanas Observatory in Chile. In the foreground the 2.5-meter du Pont Telescope is visible as well as the 1-meter SWOPE telescope. The skies beyond the meteors are highlighted by Jupiter, seen as the bright spot near the image center, the central band of our Milky Way Galaxy, seen vertically on the image left, and the pinkish Orion Nebula on the far left. Dust swept up from the orbit of active asteroid 3200 Phaethon, Gemini's meteors enter the atmosphere traveling at about 22 kilometers per second

M83 Star Streams

 Big, bright, and beautiful, spiral galaxy M83 lies a mere twelve million light-years away, near the southeastern tip of the very long constellation Hydra. This deep view of the gorgeous island universe includes observations from Hubble, along with ground based data from the European Southern Observatory's very large telescope units, National Astronomical Observatory of Japan's Subaru telescope, and Australian Astronomical Observatory photographic data by D. Malin. About 40,000 light-years across, M83 is popularly known as the Southern Pinwheel for its pronounced spiral arms. But the wealth of reddish star forming regions found near the edges of the arms' thick dust lanes, also suggest another popular moniker for M83, the Thousand-Ruby Galaxy. Arcing near the top of the novel cosmic portrait lies M83's northern stellar tidal stream, debris from the gravitational disruption of a smaller, merging satellite galaxy. The faint, elusive star stream was found in the mid 1990s by enhancing photographic plates.

The hydrogen clouds of M33.

Gorgeous spiral galaxy M33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies about 3 million light-years distant. Its inner 30,000 light-years are shown in this telescopic galaxy portrait that enhances the reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. To enhance this image, broadband data was used to produce a color view of the galaxy and combined with narrowband data recorded through a hydrogen-alpha filter, transmitting the light of the strongest hydrogen emission line. To see the monochromatic narrowband data alone, move your cursor over the image, or take this video tour of the hydrogen clouds of M33.

Storms Expected on Brown Dwarfs

This artist's concept shows what the weather might look like on cool star-like bodies known as brown dwarfs. These giant balls of gas start out life like stars, but lack the mass to sustain nuclear fusion at their cores, and instead, fade and cool with time.

That's not the young crescent Moon

 That's not the young crescent Moon poised above the western horizon at sunset. Instead it's Venus in a crescent phase, captured with a long telephoto lens from Quebec City, Canada, planet Earth on a chilly December 30th evening. The very bright celestial beacon is droping lower into the evening twilight every day. But it also grows larger in apparent size and becomes a steadily thinner crescent in binocular views as it heads toward an inferior conjunction, positioned between the Earth and the Sun on January 11. The next few evenings will see a young crescent Moon join the crescent Venus in the western twilight, though. Historically, the first observations of the phases of Venus were made by Galileo with his telescope in 1610, evidence  consistent with the Copernican model of the Solar System, but not the Ptolemaic system

Lovejoy in the New Year

A rival to vanquished Comet ISON in 2013, Comet Lovejoy (C/2013 R1) still sweeps through early morning skies, captured in this starry scene on New Year's day. The frame stretches some 3.5 degrees across a background of faint stars in the constellation Hercules. Only just visible to the naked eye from dark sites before dawn, Lovejoy remains a good target for the northern hemisphere's binocular equipped skygazers. But this deep exposure shows off Lovejoy's beautiful tails and tantalizing greenish coma better than binocular views. Not a sungrazer, this Comet Lovejoy made its closest approach to the Sun around December 22, looping high above the ecliptic plane. Now headed for the outer Solar System, Lovejoy began the new year about 6.7 light-minutes from planet Earth

Alpha Centauri is the closest star system to the Sun .

Located just next door, Alpha Centauri is the closest star system to the Sun. A view from our interstellar neighbor a mere 4.3 light-years away is shown in this illustration. The Sun is at the upper right, a bright star against the background of the Milky Way. The crescent in the foreground is an artist's rendering of a planet now reported orbiting Alpha Centauri B, making it the closest known exoplanet. Discovered by astronomer Xavier Dumusque et al. using the planet hunting HARPS instrument to measure minute shifts in the star's spectrum for more than four years, the planet has approximately the same mass as Earth. But it orbits once every 3.2 days, about 0.04 times the Earth-Sun distance from its parent star. That puts it well outside the habitable zone, much too close to Alpha Cen B, a star only a little cooler than the Sun. Still, estimates indicate that planetary orbits would be stable within the habitable zone of Alpha Cen B, at about half the Earth-Sun distance ...

Sometimes it's hard to believe what you see in the sky.

Sometimes it's hard to believe what you see in the sky. During the Shelios Expedition to Greenland in late August, even veteran sky enthusiasts saw auroras so colorful, so fast changing, and so unusual in form that they could remember nothing like it. As the ever changing auroras evolved, huge shapes spread across the sky morphed from one familiar form into another, including what looked to be the head of a goat (shown above), the head of an elephant, a strange green-tailed comet, and fingers on a celestial hand. Even without the aurora, the sky would be notable for the arching band of our Milky Way Galaxy and the interesting field of stars, nebulas, and galaxies. In contrast, in the foreground is a farm house in

M7 is one of the most prominent open clusters of stars on the sky.

M7 is one of the most prominent open clusters of stars on the sky. The cluster, dominated by bright blue stars, can be seen with the naked eye in a dark sky in the tail of the constellation of the Scorpion (Scorpius). M7 contains about 100 stars in total, is about 200 million years old, spans 25 light-years across, and lies about 1000 light-years away. The above deep image, taken last June from Hungary through a small telescope, combines over 60 two-minute exposures. The M7 star cluster has been known since ancient times, being noted by Ptolemy in the year 130 AD. Also visible are a dark dust cloud and literally millions of unrelated stars towards the Galactic center.

Nebula IC 410

This telescopic close-up shows off the otherwise faint emission nebula IC 410 in striking false-colors. It also features two remarkable inhabitants of the cosmic pond of gas and dust below and right of center, the tadpoles of IC 410. The picture is a composite of images taken through narrow band filters. The narrow band image data traces atoms in the nebula, with emission from sulfur atoms in red, hydrogen atoms in green, and oxygen in blue. Partly obscured by foreground dust, the nebula itself surrounds NGC 1893, a young galactic cluster of stars that energizes the glowing gas. Composed of denser cooler gas and dust the tadpoles are around 10 light-years long, potentially sites of ongoing star formation. Sculpted by wind and radiation from the cluster stars, their tails trail away from the cluster's central region. IC 410 lies some 12,000 light-years away, toward the constellation Auriga.

Helix Nebula

A mere seven hundred light years from Earth, in the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. A total of 28.5 hours of exposure time have gone in to creating this deep view of the nebula. Combining narrow band image data from emission lines of hydrogen atoms in red and oxygen atoms in blue-green hues, it shows remarkable details of the Helix's brighter inner region, about 3 light-years across, but also follows fainter outer halo features that give the nebula a span of well over six light-years. The white dot at the Helix's center is this Planetary Nebula's hot, central star. A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.

The Seagull Nebula

A broad expanse of glowing gas and dust presents a bird-like visage to astronomers from planet Earth, suggesting its popular moniker - The Seagull Nebula. This portrait of the cosmic bird covers a 1.6 degree wide swath across the plane of the Milky Way, near the direction of Sirius, alpha star of the constellation Canis Major. Of course, the region includes objects with other catalog designations: notably NGC 2327, a compact, dusty emission region with an embedded massive star that forms the bird's head (aka the Parrot Nebula, above center). Dominated by the reddish glow of atomic hydrogen, the complex of gas and dust clouds with bright young stars spans over 100 light-years at an estimated 3,800 light-year distance.

Orion Nebula

Explanation: Few cosmic vistas excite the imagination like the Orion Nebula, an immense stellar nursery some 1,500 light-years away. This stunning false-color view spans about 40 light-years across the region, constructed using infrared data from the Spitzer Space Telescope. Compared to its visual wavelength appearance, the brightest portion of the nebula is likewise centered on Orion's young, massive, hot stars, known as the Trapezium Cluster. But the infrared image also detects the nebula's many protostars, still in the process of formation, seen here in red hues. In fact, red spots along the dark dusty filament to the left of the bright cluster include the protostar cataloged as HOPS 68, recently found to have crystals of the silicate mineral olivine within its protostellar envelope

Is the night sky darkest in the direction opposite the Sun?

Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles. These dust particles are millimeter sized splinters from asteroids and orbit in the ecliptic plane of the planets. Pictured above from last year is one of the more spectacular pictures of the gegenschein yet taken. Here a deep exposure of an extremely dark sky over Las Campanas Observatory in Chile shows the gegenschein so clearly that even a surrounding glow is visible. Notable background objects include the Andromeda galaxy, the Pleiades star cluster, the California Nebula, the belt of Orion just below the Orion Nebula and inside Barnard's Loop, and bright stars Rigel and Betelgeuse. The gegenschein is distinguished from zodiacal light near the Sun by the high angle of reflection. During the day, a phenomenon similar to the gegenschein called the glory can be seen in reflecting air or clouds opposite the Sun from an airplane .

What are black hole jets made of ?

Explanation: What are black hole jets made of? Many black holes in stellar systems are surely surrounded by disks of gas and plasma gravitationally pulled from a close binary star companion. Some of this material, after approaching the black hole, ends up being expelled from the star system in powerful jets emanating from the poles of the spinning black hole. Recent evidence indicates that these jets are composed not only electrons and protons, but also the nuclei of heavy elements such as iron and nickel. The discovery was made in system 4U1630-47 using CSIRO’s Compact Array of radio telescopes in eastern Australia, and the European Space Agency's Earth-orbiting XMM-Newton satellite. The 4U1630-47 star system is depicted above in an artist's illustration, with a large blue star on the right and jets emanating from a black hole in the center of the accretion disc on the left. Although the 4U1630-47 star system is thought to contain only a small black hole -- a few times the mass of our Sun -- the implications of the results may be larger: that black holes of larger sizes might also be emitting jets of massive nuclei into the cosmos.

Sunspot

Explanation: Sunsets may be the most watched celestial event, but lately sunsets have even offered something extra. A sunspot so large it was visible to the naked eye is captured in Swiss skies in this sunset scene from January 5, crossing left to right near the center of a solar disk dimmed and distorted by Earth's dense atomosphere. Detailed views reveal a large solar active region composed of sunspots, some larger than planet Earth itself. Cataloged as active region AR 1944, on January 7 it produced a substantial solar flare and a coronal mass ejection (CME) forecast to reach Earth. The CME could trigger geomagnetic storms and aurora on January 9

Milky Way Over the Bungle Bungles

Explanation: Which part of this picture do you find more interesting -- the land or the sky? Advocates for the land might cite the beauty of the ancient domes of the Bungle Bungle Range in Western Australia. These picturesque domes appear as huge layered beehives and are made of sandstones and conglomerates deposited over 350 million years ago. Advocates for the sky might laud the beauty of the Milky Way's central band shown arching from horizon to horizon. The photogenic Milky Way band formed over 10 billion years ago and now includes many well-known nebulae and bright stars. Fortunately, you don't have to decide and can enjoy both together in this beautiful 8-frame panorama taken from the dark skies of Purnululu National Park about two months ago .

What's happening to galaxy NGC 474 ?

Explanation: What's happening to galaxy NGC 474? The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the elliptical galaxy in less deep images. The cause of the shells is currently unknown, but possibly tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the shells may be like ripples in a pond, where the ongoing collision with the spiral galaxy just above NGC 474 is causing density waves to ripple though the galactic giant. Regardless of the actual cause, the above image dramatically highlights the increasing consensus that at least some elliptical galaxies have formed in the recent past, and that the outer halos of most large galaxies are not really smooth but have complexities induced by frequent interactions with -- and accretions of -- smaller nearby galaxies. The halo of our own Milky Way Galaxy is one example of such unexpected complexity. NGC 474 spans about 250,000 light years and lies about 100 million light years distant toward the constellation of the Fish (Pisces)

How far away is spiral galaxy NGC 4921?

How far away is spiral galaxy NGC 4921? Although presently estimated to be about 310 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe. Toward this goal, several images were taken by the Hubble Space Telescope in order to help identify key stellar distance markers known as Cepheid variable stars. Since NGC 4921 is a member of the Coma Cluster of Galaxies, refining its distance would also allow a better distance determination to one of the largest nearby clusters in the local universe. The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness. Visible in the above image are, from the center, a bright nucleus, a bright central bar, a prominent ring of dark dust, blue clusters of recently formed stars, several smaller companion galaxies, unrelated galaxies in the far distant universe, and unrelated stars in our Milky Way Galaxy.

The Bubble and M52

Explanation: To the eye, this cosmic composition nicely balances the Bubble Nebula at the lower left with open star cluster M52 above it and to the right. The pair would be lopsided on other scales, though. Embedded in a complex of interstellar dust and gas and blown by the winds from a single, massive O-type star, the Bubble Nebula, also known as NGC 7635, is a mere 10 light-years wide. On the other hand, M52 is a rich open cluster of around a thousand stars. The cluster is about 25 light-years across. Seen toward the northern boundary of Cassiopeia, distance estimates for the Bubble Nebula and associated cloud complex are around 11,000 light-years, while star cluster M52 lies nearly 5,000 light-years away. The wide telescopic field of view spans about two degrees on the sky or four times the apparent size of the Full Moon.

Cometary Globules

Explanation: Bright-rimmed, flowing shapes gather near the centre of this rich starfield toward the boarders of the nautical southern constellations Pupis and Vela. Composed of interstellar gas and dust, the grouping of light-year sized cometary globules is about 1300 light-years distant. Energetic ultraviolet light from nearby hot stars has molded the globules and ionized their bright rims. The globules also stream away from the Vela supernova remnant which may have influenced their swept-back shapes. Within them, cores of cold gas and dust are likely collapsing to form low mass stars, whose formation will ultimately cause the globules to disperse. 

M78: Stardust and Starlight

Explanation: Interstellar dust clouds and bright nebulae abound in the fertile constellation of Orion. One of the brightest, M78, is just left of center in this colorful telescopic view, covering an area north of Orion's belt. At a distance of about 1,500 light-years, the bluish nebula itself is about 5 light-years across. Its blue tint is due to dust preferentially reflecting the blue light of hot, young stars in the region. Dark dust lanes and other nebulae can easily be traced through this gorgeous skyscape. The scene also includes the remarkable McNeil's Nebula -- a newly recognized nebula associated with the formation of a sun-like star, and the telltale reddish glow of many Herbig- Haro objects, energetic jets from stars in the process of formation.

Hubble Remix: Active Galaxy NGC 1275

Explanation: Active galaxy NGC 1275 is the central, dominant member of the large and relatively nearby Perseus Cluster of Galaxies. Wild-looking at visible wavelengths, the active galaxy is also a prodigious source of x-rays and radio emission. NGC 1275 accretes matter as entire galaxies fall into it, ultimately feeding a supermassive black hole at the galaxy's core. This color composite image, recreated from archival Hubble Space Telescope data, highlights the resulting galactic debris and filaments of glowing gas, some up to 20,000 light-years long. The filaments persist in NGC 1275, even though the turmoil of galactic collisions should destroy them. What keeps the filaments together? Observations indicate that the structures, pushed out from the galaxy's center by the black hole's activity, are held together by magnetic fields. Also known as Perseus A, NGC 1275 spans over 100,000 light years and lies about 230 million light years away.

Filaments of the Vela Supernova Remnan

Explanation: The explosion is over but the consequences continue. About eleven thousand years ago a star in the constellation of Vela could be seen to explode, creating a strange point of light briefly visible to humans living near the beginning of recorded history. The outer layers of the star crashed into the interstellar medium, driving a shock wave that is still visible today. A roughly spherical, expanding shock wave is visible in X-rays. The above image captures some of that filamentary and gigantic shock in visible light. As gas flies away from the detonated star, it decays and reacts with the interstellar medium, producing light in many different colors and energy bands. Remaining at the center of the Vela Supernova Remnant is a pulsar, a star as dense as nuclear matter that rotates completely around more than ten times in a single second.

All the Colors of the Su

Explanation: It is still not known why the Sun's light is missing some colors. Here are all the visible colors of the Sun, produced by passing the Sun's light through a prism-like device. The spectrum was created at the McMath-Pierce Solar Observatory and shows, first off, that although our white-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..

Cometary Globule

Explanation: Bright-rimmed, flowing shapes gather near the centre of this rich starfield toward the boarders of the nautical southern constellations Pupis and Vela. Composed of interstellar gas and dust, the grouping of light-year sized cometary globules is about 1300 light-years distant. Energetic ultraviolet light from nearby hot stars has molded the globules and ionized their bright rims. The globules also stream away from the Vela supernova remnant which may have influenced their swept-back shapes. Within them, cores of cold gas and dust are likely collapsing to form low mass stars, whose formation will ultimately cause the globules to disperse.