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Gigagalaxy Zoom: Milky Way Credit: ESO / Serge Brunier, Frederic Tapissier - Copyright: Serge Brunier (TWAN) Explanation: Our magnificent Milky Way Galaxy sprawls across this ambitious all-sky panorama. In fact, at 800 million pixels the full resolution mosaic strives to show all the stars the eye can see in planet Earth's night sky. Part of ESO's Gigagalaxy Zoom Project, the mosaicked images were recorded over several months of 2008 and 2009 at exceptional astronomical sites; the Atacama Desert in the southern hemisphere and the Canary Islands in the northern hemisphere. Also capturing bright planets and even a comet, the...

Equinox Sunset Credit & Copyright:> Tamas Ladanyi (TWAN) Explanation: Often inspiring, or offering a moment for contemplation, a sunset is probably the most commonly photographed celestial event. But this uncommonly beautiful sunset picture was taken on a special day, the Equinox on September 22. Marking the astronomical change of seasons, on that day Earth dwellers experienced nearly 12 hours of daylight and 12 hours of darkness (an equal night). Reflected in the calm waters of Lake Balaton with a motionless sailboat in silhouette, the Sun is setting due west and heading south across the celestial equator. In the background...

Equinox Sunset Explanation: Often inspiring, or offering a moment for contemplation, a sunset is probably the most commonly photographed celestial event. But this uncommonly beautiful sunset picture was taken on a special day, the Equinox on September 22. Marking the astronomical change of seasons, on that day Earth dwellers experienced nearly 12 hours of daylight and 12 hours of darkness (an equal night). Reflected in the calm waters of Lake Balaton with a motionless sailboat in silhouette, the Sun is setting due west and heading south across the celestial equator. In the background lies the Benedictine Archabbey of Tihany, Hungary.

Aurora Over Yellowknife Credit & Copyright: Yuichi Takasaka (Blue Moon Promotions), TWAN Explanation: Sometimes, after your eyes adapt to the dark, a spectacular sky appears. In this case, a picturesque lake lies in front of you, beautiful green auroras flap high above you, brilliant stars shine far in the distance, and a brilliant moon shines just ahead of you. This digitally fused panorama was captured earlier this month from Yellowknife, Northwest Territories, Canada, and includes the Pleiades open cluster of stars just to the upper right of the Moon. Since aurora are ultimately started by solar activity, this current...

Abell 370: Galaxy Cluster Gravitational Lens Credit: NASA, ESA, and the Hubble SM4 ERO Team & ST-ECF Explanation: What is that strange arc? While imaging the cluster of galaxies Abell 370, astronomers had noted an unusual arc to the right of many cluster galaxies. Although curious, one initial response was to avoid commenting on the arc because nothing like it had ever been noted before. In the mid-1980s, however, better images allowed astronomers to identify the arc as a prototype of a new kind of astrophysical phenomenon -- the gravitational lens effect of entire cluster of galaxies on background...

NGC 3621: Far Beyond the Local Group Credit & Copyright: Robert Gendler Explanation: Far beyond the local group of galaxies lies NGC 3621, some 22 million light-years away. Found in the multi-headed southern constellation Hydra, the winding spiral arms of this gorgeous island universe are loaded with luminous young star clusters and dark dust lanes. Still, for earthbound astronomers NGC 3621 is not just another pretty face-on spiral galaxy. Some of its brighter stars have been used as standard candles to establish important estimates of extragalactic distances and the scale of the Universe. This beautiful image of NGC 3621...

The Tarantula Zone Credit & Copyright: John P. Gleason Explanation: The Tarantula Nebula is more than 1,000 light-years in diameter -- a giant star forming region within our neighboring galaxy the Large Magellanic Cloud (LMC). That cosmic arachnid lies left of center in this sharp, colorful telescopic image taken through narrow-band filters. It covers a part of the LMC over 2,000 light-years across. Within the Tarantula (NGC 2070), intense radiation, stellar winds and supernova shocks from the central young cluster of massive stars, cataloged as R136, energize the nebular glow and shape the spidery filaments. Around the Tarantula are...

NGC 6888: The Crescent Nebula Credit & Copyright: Daniel López, IAC Explanation: NGC 6888, also known as the Crescent Nebula, is a cosmic bubble about 25 light-years across, blown by winds from its central, bright, massive star. This beautiful portrait of the nebula is from the Isaac Newton Telescope at Roque de los Muchachos Observatory in the Canary Islands. It combines a composite color image with narrow band data that isolates light from hydrogen and oxygen atoms in the wind-blown nebula. The oxygen atoms produce the blue-green hue that seems to enshroud the detailed folds and filaments. NGC 6888's...

The Center of Globular Cluster Omega Centauri Credit: NASA, ESA, and the Hubble SM4 ERO Team Explanation: What is left over after stars collide? To help answer this question, astronomers have been studying the center of the most massive ball of stars in our Milky Way Galaxy. In the center of globular cluster Omega Centauri, stars are packed in 10,000 times more densely than near our Sun. Pictured above, the newly upgraded Hubble Space Telescope has resolved the very center of Omega Centauri into individual stars. Visible are many faint yellow-white stars that are smaller than our Sun, several...

Stephan's Quintet Credit: NASA, ESA, and the Hubble SM4 ERO Team Explanation: The first identified compact galaxy group, Stephan's Quintet is featured in this stunning image from the newly upgraded Hubble Space Telescope. About 300 million light-years away, only four galaxies of the group are actually locked in a cosmic dance of repeated close encounters. The odd man out is easy to spot, though. The four interacting galaxies (NGC 7319, 7318A, 7318B, and 7317) have an overall yellowish cast and tend to have distorted loops and tails, grown under the influence of disruptive gravitational tides. But the bluish galaxy...

The Butterfly Nebula from Upgraded Hubble Credit: NASA, ESA, and the Hubble SM4 ERO Team Explanation: The bright clusters and nebulae of planet Earth's night sky are often named for flowers or insects, and NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the central star of this particular planetary nebula is exceptionally hot though -- shining brightly in ultraviolet light but hidden from direct view by a dense torus of dust. Above is a dramatically detailed close-up of the dying star's nebula recorded by the newly upgraded Hubble Space Telescope. Cutting across...

Unexpected Impact on Jupiter Credit: ALPO, Theo Ramakers Explanation: Two months ago, something unexpected hit Jupiter. First discovered by an amateur astronomer Anthony Wesley on 2009 July 19, the impact was quickly confirmed and even imaged by the Hubble Space Telescope the very next day. Many of the world's telescopes then zoomed in on our Solar System's largest planet to see the result. Some of these images have been complied into the above animation. Over the course of the last month and a half, the above time-lapse sequence shows the dark spot -- first created when Jupiter was struck...

Jupiter Over the Mediterranean Credit & Copyright: Tunç Tezel (TWAN) Explanation: This vacation included a sight to remember. Pictured above, a picturesque starscape capped a serene seascape as seen from Turkey this past August. In the above digitally stitched panorama, the Gelidonya Lighthouse shines in the foreground before a calm Mediterranean Sea. On the left, Jupiter is the brightest point in the image and since on the same side of the Sun as the Earth, was near its yearly brightest. Glowing just shy of magnitude -3, Jupiter was brighter than any star in the sky, and brighter even than...

CMBR Dipole: Speeding Through the Universe Credit: DMR, COBE, NASA, Four-Year Sky Map Explanation: Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies. But these speeds are less than the speed that all of these objects together move relative to the cosmic microwave background radiation (CMBR). In the above all-sky map from the COBE satellite, radiation in the Earth's direction of motion appears blueshifted and...

Supernova Remnant E0102-72 Credit: X-ray - NASA / CXC / MIT / D.Dewey et al., NASA / CXC / SAO / J.DePasquale; Optical - NASA / STScI Explanation: The expanding debris cloud from the explosion of a massive star is captured in this multiwavelength composite, combining x-ray and optical images from the Chandra and Hubble telescopes. Identified as E0102-72, the supernova remnant lies about 190,000 light-years away in our neighboring galaxy, the Small Magellanic Cloud. A strong cosmic source of x-rays, E0102 was imaged by the Chandra X-ray Observatory shortly after its launch in 1999. In celebration of Chandra's 10th...

6 Years of Saturn Credit & Copyright: Alan Friedman Explanation: Today, planet Earth passes through the plane of Saturn's rings. From the perspective of earthbound astronomers, Saturn's rings will be edge-on. The problem is, Saturn itself is now very close to the Sun, low on horizon after sunset, so good telescopic images will be difficult to come by. Still, this composite of Saturn views taken from 2004 - 2009 (lower right to upper left) illustrates the change in ring tilt over the last six years and includes a nearly edge-on ring view, based on images captured earlier this year....

Despina, Moon of Neptune Credit: NASA, JPL, Ted Stryk Explanation: Despina is a tiny moon of Neptune. A mere 148 kilometers across, diminutive Despina was discovered in 1989, in images from the Voyager 2 spacecraft taken during its encounter with the solar system's most distant gas giant planet. But looking through the Voyager 2 data 20 years later, amateur image processor (and philosophy professor) Ted Stryk discovered something no one had recognized before -- images that show the shadow of Despina in transit across Neptune's blue cloud tops. His composite view of Despina and its shadow is composed of...

Discovery's Rainbow Credit: NASA, Ben Cooper (Launch Photography) Explanation: Just one minute before midnight EDT, Friday, August 28, the Space Shuttle Discovery began a long arc into a cloudy sky. Following the launch, a bright and remarkably colorful trail was captured in this time exposure from the Banana River Viewing Site, looking east toward pad 39A at the Kennedy Space Center. On STS-128, Discovery docked with the International Space Station Sunday evening. The 13-day mission will exchange space station crew members and deliver more than 7 tons of supplies and equipment. Of course, the equipment includes the Combined Operational...

Shadows of Saturn at Equinox Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA Explanation: Unusual shadows and dark rings appeared around Saturn near its equinox last month. At that time -- early August -- Saturn's ring plane pointed directly at the Sun. Visible above, Saturn's moon Tethys casts a shadow visible only on the far right. Saturn's own shadow blacks out a large swath of rings on the right. The night side of Saturn glows with ringshine -- sunlight reflected by ring particles back onto Saturn. Images near equinox at Saturn are giving astronomers a chance to search for...

Open Cluster M25 Credit & Copyright: Jean-Charles Cuillandre (CFHT) & Giovanni Anselmi (Coelum Astronomia), Hawaiian Starlight Explanation: Many stars like our Sun were formed in open clusters. The above pictured open cluster, M25, contains thousands of stars and is about two thousand light years distant. The stars in this cluster all formed together about 90 million years ago. The bright young stars in M25 appear blue. Open clusters, also called galactic clusters, contain fewer and younger stars than globular clusters. Also unlike globular clusters, open clusters are generally confined to the plane of our Galaxy. M25 is visible with...