NGC 4945 in Centaurus Credit & Copyright: Dietmar Hager, Thorsten Brandes Explanation: Large, dusty, spiral galaxy NGC 4945 is seen edge-on near the center of this rich telescopic image. The field of view spans nearly 2 degrees, or about 4 times the width of the Full Moon, toward the expansive southern constellation Centaurus. About 13 million light-years distant, NGC 4945 is almost the size of our own Milky Way Galaxy. But X-ray and infrared observations reveal even more high energy emission and star formation in the core of NGC 4945. The other prominent galaxy in the field, NGC 4976, is an elliptical galaxy. Left of center, NGC 4976 is much farther away, at a distance of about 35 million light-years, and not physically associated with NGC 4945.
In the Shadow of Saturn Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA Explanation: In the shadow of Saturn, unexpected wonders appear. The robotic Cassini spacecraft now orbiting Saturn recently drifted in giant planet's shadow for about 12 hours and looked back toward the eclipsed Sun. Cassini saw a view unlike any other. First, the night side of Saturn is seen to be partly lit by light reflected from its own majestic ring system. Next, the rings themselves appear dark when silhouetted against Saturn, but quite bright when viewed away from Saturn and slightly scattering sunlight, in the above exaggerated color image. Saturn's rings light up so much that new rings were discovered, although they are hard to see in the above image. Visible in spectacular detail, however, is Saturn's E ring, the ring created by the newly discovered ice-fountains of the moon Enceladus, and the outermost ring visible above. Far in the distance, visible on the image left just above the bright main rings, is the almost ignorable pale blue dot of Earth.
NGC 2170: Celestial Still Life Credit & Copyright: Thomas V. Davis (tvdavisastropix.com) Explanation: Is this a painting or a photograph? In this beautiful celestial still life composed with a cosmic brush, dusty nebula NGC 2170 shines near the image center. Reflecting the light of nearby hot stars, NGC 2170 is joined by other bluish reflection nebulae, a red emission region, many dark absorption nebulae, and a backdrop of colorful stars. Like the common household items still life painters often choose for their subjects, the clouds of gas, dust, and hot stars pictured here are also commonly found in this setting - a massive, star-forming molecular cloud in the constellation Monoceros. The giant molecular cloud, Mon R2, is impressively close, estimated to be only 2,400 light-years or so away. At that distance, this canvas would be over 40 light-years across.
IC 410 and NGC 1893 Credit & Copyright: Jacob Bass?e Explanation: Dusty emission nebula IC 410 lies about 12,000 light-years away in the northern constellation Auriga. The cloud of glowing 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 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. Emission from sulfur atoms is shown in red, hydrogen atoms in green, and oxygen in blue hues in this false-color, narrow band composite image.
AE Aurigae and the Flaming Star Nebula Credit & Copyright: Jorge Garcia Explanation: Is star AE Aurigae on fire? No. Even though AE Aurigae is named the flaming star, the surrounding nebula IC 405 is named the Flaming Star Nebula, and the region appears to harbor red smoke, there is no fire. Fire, typically defined as the rapid molecular acquisition of oxygen, happens only when sufficient oxygen is present and is not important in such high-energy, low-oxygen environments such as stars. The material that appears as smoke is mostly interstellar hydrogen, but does contain smoke-like dark filaments of carbon-rich dust grains. The bright star AE Aurigae, visible near the nebula center, is so hot it is blue, emitting light so energetic it knocks electrons away from surrounding gas. When a proton recaptures an electron, red light is frequently emitted, as seen in the surrounding emission nebula. Pictured above, the Flaming Star nebula lies about 1,500 light years distant, spans about 5 light years, and is visible with a small telescope toward the constellation of the Charioteer (Auriga).
A Partial Eclipse Over Manila Bay Credit & Copyright: Armando Lee (Astron. League Philippines), 100 Hours of Astronomy (IYA2009) Explanation: What's happened to the setting Sun? An eclipse! Two days ago, the Moon eclipsed part of the Sun as visible from parts of Africa, Australia, and Asia. In particular the above image, taken from the Mall of Asia seawall, caught a partially eclipsed Sun setting over Manila Bay in the Philippines. Piers are visible in silhouette in the foreground. Eclipse chasers and well placed sky enthusiasts captured many other interesting and artistic images of the year's only annular solar eclipse, including movies, eclipse shadow arrays, and rings of fire. Another partial solar eclipse will be visible from the Philippines in July. That event, however, will likely be better remembered as a total solar eclipse visible to those occupying a long thin swath of Earth that starts in India and extends through China into the Pacific Ocean.
Simeis 147: Supernova Remnant Credit & Copyright: J-P Mets?vainio (Astro Anarchy) Explanation: It's easy to get lost following the intricate filaments in this detailed image of faint supernova remnant Simeis 147. Also cataloged as Sh2-240 and seen towards the constellation Taurus, it covers nearly 3 degrees (6 full moons) on the sky. That corresponds to a width of 150 light-years at the stellar debris cloud's estimated distance of 3,000 light-years. The remarkable narrow-band composite image in the Hubble color palette includes emission from hydrogen, sulfur, and oxygen atoms tracing regions of shocked, glowing gas. This supernova remnant has an estimated age of about 40,000 years - meaning light from the massive stellar explosion first reached Earth 40,000 years ago. But this expanding remnant is not the only aftermath. The cosmic catastrophe also left behind a spinning neutron star or pulsar, all that remains of the original star's core.
NGC 604: X-rays from a Giant Stellar Nursery Credit: X-ray: NASA / CXC / R. Tuellmann (Harvard-Smithsonian CfA) et al.; Optical: NASA/AURA/STScI Explanation: Some 3 million light-years distant in nearby spiral galaxy M33, giant stellar nursery NGC 604 is about 1,300 light-years across, or nearly 100 times the size of the Orion Nebula. In fact, among the star forming regions within the Local Group of galaxies, NGC 604 is second in size only to 30 Doradus, also known as the Tarantula Nebula in the Large Magellanic Cloud. This space-age color composite of X-ray data (in blue hues) from the Chandra Observatory, and Hubble optical data shows that NGC 604's cavernous bubbles and cavities are filled with a hot, tenuous, X-ray emitting gas. Intriguingly, NGC 604 itself is divided by a wall of relatively cool gas. On the western (right) side of the nebula, measurements indicate that material is likely heated to X-ray temperatures by the energetic winds from a cluster of about 200 young, massive stars. On the eastern side the X-ray filled cavities seem to be older, suggesting supernova explosions from the end of massive star evolution contribute to their formation.
Anemic Galaxy NGC 4921 at the Edge Credit: NASA, ESA, K. Cook (LLNL) Explanation: How far away is spiral galaxy NGC 4921? Although presently estimated to be about 320 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, this image was taken by the Hubble Space Telescope in order to help identify key stellar distance markers know 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. The remarkably sharp image was made with Hubble's Advanced Camera for Surveys, currently in need of repair. Visible in the 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.
Inside the Eagle Nebula Credit & Copyright: T. A. Rector & B. A. Wolpa, NOAO, AURA Explanation: From afar, the whole thing looks like an Eagle. A closer look at the Eagle Nebula, however, shows the bright region is actually a window into the center of a larger dark shell of dust. Through this window, a brightly-lit workshop appears where a whole open cluster of stars is being formed. In this cavity tall pillars and round globules of dark dust and cold molecular gas remain where stars are still forming. Already visible are several young bright blue stars whose light and winds are burning away and pushing back the remaining filaments and walls of gas and dust. The Eagle emission nebula, tagged M16, lies about 6500 light years away, spans about 20 light-years, and is visible with binoculars toward the constellation of the Serpent (Serpens). This picture combines three specific emitted colors and was taken with the 0.9-meter telescope on Kitt Peak, Arizona, USA.
Orion's Belt Credit & Copyright: Martin Mutti, Astronomical Image Data Archive Explanation: Alnitak, Alnilam, and Mintaka, are the bright bluish stars from east to west (left to right) along the diagonal in this gorgeous cosmic vista. Otherwise known as the Belt of Orion, these three blue supergiant stars are hotter and much more massive than the Sun. They lie about 1,500 light-years away, born of Orion's well-studied interstellar clouds. In fact, clouds of gas and dust adrift in this region have intriguing and some surprisingly familiar shapes, including the dark Horsehead Nebula and Flame Nebula near Alnitak at the lower left. The famous Orion Nebula itself lies off the bottom of this star field that covers about 4.5x3.5 degrees on the sky. This image was taken last month with a digital camera attached to a small telescope in Switzerland, and better matches human color perception than a more detailed composite taken over 15 years ago.
Zodiacal Light Vs. Milky Way Credit & Copyright: Daniel L?pez, IAC Explanation: Two fundamental planes of planet Earth's sky compete for attention in this remarkable wide-angle vista, recorded on January 23rd. Arcing above the horizon and into the night at the left is a beautiful band of Zodiacal Light - sunlight scattered by dust in the solar system's ecliptic plane. Its opponent on the right is composed of the faint stars, dust clouds, and nebulae along the plane of our Milky Way Galaxy. Both celestial bands stand above the domes and towers of the Teide Observatory on the island of Tenerife. Also out to play in the pristine, dark skies over the Canary Islands, are brilliant Venus (lower left), the distant Andromeda Galaxy (near center), and the lovely Pleiades star cluster (top center). Of course, seasoned skygazers might even spot M33, the California Nebula, IC1805, and the double star cluster of Perseus. (Need some help? Just slide your cursor over the picture.)
Snake in the Dark Credit & Copyright: St?phane Guisard (Los Cielos de Chile) Explanation: Dark nebulae snake across a gorgeous expanse of stars in this telescopic view toward the pronounceable constellation Ophiuchus and the center of our Milky Way Galaxy. In fact, the twisting central shape seen here is well known as the Snake Nebula. It is also listed as Barnard 72 (B72), one of 182 dark markings of the sky cataloged in the early 20th century by astronomer E. E. Barnard. Unlike bright emission nebulae and star clusters, Barnard's nebulae are interstellar dark clouds of obscuring gas and dust. Their shapes are visible in cosmic silhouette because they lie in the foreground along the line of sight to rich star fields and glowing stellar nurseries near the plane of our Galaxy. Many of Barnard's dark nebulae are themselves likely sites of future star formation. Barnard 72 is about 650 light years away. With bluish star 44 Ophiuchi at bottom left, the intriguing star field spans nearly 2 degrees or almost 20 light-years at the estimated distance of the Snake Nebula.
Orion Nebula: The Hubble View Credit: NASA, ESA, M. Robberto (STScI/ESA) et al Explanation: Few cosmic vistas excite the imagination like the Orion Nebula. Also known as M42, the nebula's glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud only 1,500 light-years away. The Orion Nebula offers one of the best opportunities to study how stars are born partly because it is the nearest large star-forming region, but also because the nebula's energetic stars have blown away obscuring gas and dust clouds that would otherwise block our view - providing an intimate look at a range of ongoing stages of starbirth and evolution. This detailed image of the Orion Nebula is the sharpest ever, constructed using data from the Hubble Space Telescope's Advanced Camera for Surveys and the European Southern Observatory's La Silla 2.2 meter telescope. The mosaic contains a billion pixels at full resolution and reveals about 3,000 stars.
Late yester evening, I espied a great disturbance on the horizon. I uncapped my telescope, focused in on the disturbance, and viewed this... I hope we are able to resist the invasion.
Two Tails of Comet Lulin] Credit & Copyright: Richard Richins (NMSU) Explanation: Go outside tonight and see Comet Lulin. From a dark location, you should need only a good star map and admirable perseverance -- although wide-field binoculars might help. Yesterday, Comet Lulin passed its closest to Earth, so that the comet will remain near its brightest over the next few days. The comet is currently almost 180 degrees around from the Sun and so visible nearly all night long, but will appear to move on the sky about 10 full moons a night. Pictured above, Comet Lulin was captured in spectacular form two nights ago from New Mexico, USA. The central coma of the comet is appearing quite green, a color likely indicating glowing cyanogen and molecular carbon gasses. Bright stars and a distant spiral galaxy are clearly visible in the image background. The yellow dust tail, reflecting sunlight, is visible sprawling to the coma's left trailing behind the comet, while the textured bluish-glowing ion tail is visible to the coma's right, pointing away from the Sun. Over the past few weeks, from the current vantage point of Earth, these two tails appeared to point in opposite directions. Comet Lulin is expected to slowly fade over the next few weeks.
NGC 2442: Galaxy in Volans Credit & Copyright: Martin Pugh Explanation: Distorted galaxy NGC 2442 can be found in the southern constellation of the flying fish, (Piscis) Volans. Located about 50 million light-years away, the galaxy's two spiral arms extending from a pronounced central bar give it a hook-shaped appearance. This deep color image also shows the arms' obscuring dust lanes, young blue star clusters and reddish star forming regions surrounding a core of yellowish light from an older population of stars. But the star forming regions seem more concentrated along the drawn-out (right side) spiral arm. The distorted structure is likely the result of an ancient close encounter with the smaller galaxy seen near the top left of this field of view. The two interacting galaxies are separated by about 150,000 light-years at the estimated distance of NGC 2442.
IC 5146: The Cocoon Nebula Credit & Copyright: Neil Fleming, David Plesko Explanation: Inside the Cocoon Nebula is a newly developing cluster of stars. Cataloged as IC 5146, the beautiful nebula is nearly 15 light-years wide, located some 4,000 light years away toward the northern constellation Cygnus. Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by young, hot stars and blue, dust-reflected starlight at the edge of an otherwise invisible molecular cloud. In fact, the bright star near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it clears out a cavity in the molecular cloud's star forming dust and gas. This exceptionally deep color view of the Cocoon Nebula traces tantalizing features within and surrounding the dusty stellar nursery.
Comet Lulin and Distant Galaxies Credit & Copyright: Johannes Schedler (Panther Observatory) Explanation: Now fading in our night sky, Comet Lulin has provided some lovely cosmic vistas. Moving rapidly against the background of stars, Lulin briefly posed with the likes of Saturn, and Regulus (Alpha Leo). But here it is seen against a field of distant galaxies. To reveal the faint background galaxies and trace the comet's fading tail, the remarkable picture is a blended composite of telescopic exposures aligned with the both the stars and the speedy comet. The largest galaxies seen left of the comet's head or coma are cataloged as NGC 3016, NGC 3019, NGC 3020 and NGC 3024 and lie at a distance of 100 million light-years or so. When the exposures were made, on February 28, the comet was about 3.6 light-minutes from Earth.
Gibbous Europa Credit: Galileo Project, JPL, NASA; reprocessed by Ted Stryk Explanation: Although the phase of this moon might appear familiar, the moon itself might not. In fact, this gibbous phase shows part of Jupiter's moon Europa. The robot spacecraft Galileo captured this image mosaic during its mission orbiting Jupiter from 1995 - 2003. Visible are plains of bright ice, cracks that run to the horizon, and dark patches that likely contain both ice and dirt. Raised terrain is particularly apparent near the terminator, where it casts shadows. Europa is nearly the same size as Earth's Moon, but much smoother, showing few highlands or large impact craters. Evidence and images from the Galileo spacecraft, indicated that liquid oceans might exist below the icy surface. To test speculation that these seas hold life, ESA and NASA have together started preliminary development of the Europa Jupiter System Mission , a spacecraft proposed to better study Europa. If the surface ice is thin enough, a future mission might drop hydrobots to burrow into the oceans and search for life.
