Astronomy Picture of the Day (General/Chat)
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Mount Rushmore's Starry Night Credit & Copyright: Wally Pacholka (TWAN) Explanation: This starry night sky sparkles above the Black Hills of South Dakota and the United States' Mount Rushmore National Park. The historic site features enormous sculptures of four US presidents; George Washington, Thomas Jefferson, Theodore Roosevelt and Abraham Lincoln, carved into the southeast face of granite cliffs. Above the monumental symbols of the country's independence and early history, the night features stars and constellations familiar to northern skygazers around the world. Most noticeable are the stars of Ursa Major and the asterism known as the Big Dipper, almost resting...
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Perihelion and Aphelion Credit & Copyright: Enrique Luque Cervigón Explanation: This year Aphelion, the point in Earth's elliptical orbit when it is farthest from the Sun, occurs tomorrow, July 4th. Of course, that doesn't affect the seasons on our fair planet. Those are determined by the tilt of Earth's axis of rotation and not Earth's distance from the Sun, so July is still winter in the south and summer in northern hemisphere. But it does mean that on July 4th the Sun will be at its smallest apparent size. This composite neatly compares two pictures of the Sun taken with...
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Lyman Alpha Blob Credit: NASA / ESA, CXC, JPL-Caltech, STScI, NAOJ, J.E. Geach (Univ. Durham) et al. Illustration: NASA/CXC/M.Weiss Explanation: Dubbed a Lyman-alpha blob, an enormous cloud of hydrogen gas spans several hundred thousand light-years in this remarkable image (left), a composite of x-ray, optical, and infrared data from space and ground based observatories. The gigantic, amoeba-like structure is seen as it was when the universe was a mere 2 billion years old (about 12 billion years ago). Lyman-alpha blobs are so called because they strongly emit radiation due to the Lyman-alpha emission line of hydrogen gas. Normally, Lyman-alpha emission...
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Three Galaxies in Draco Credit & Copyright: Giovanni Benintende Explanation: This intriguing trio of galaxies is sometimes called the Draco Group, located in the northern constellation of (you guessed it) Draco. From left to right are edge-on spiral NGC 5981, elliptical galaxy NGC 5982, and face-on spiral NGC 5985 -- all within this single telescopic field of view spanning a little more than half the width of the full moon. While the group is far too small to be a galaxy cluster and has not been cataloged compact group, these galaxies all do lie roughly 100 million light-years from planet...
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The North America and Pelican Nebulae Credit & Copyright: Danny Lee Russell 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 1,500 light-years away, and are separated by a dark absorption cloud. This spectacular image captures the nebulas, bright ionization fronts, and fine details of...
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Fresh Tiger Stripes on Saturn's Enceladus Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA Explanation: Do underground oceans vent through the tiger stripes on Saturn's moon Enceladus? Long features dubbed tiger stripes are known to be spewing ice from the moon's icy interior into space, creating a cloud of fine ice particles over the moon's South Pole and creating Saturn's mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft now orbiting Saturn. Pictured above, a high resolution image of Enceladus is shown from a close flyby. The unusual surface features dubbed tiger stripes are visible on...
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Sarychev Peak Volcano in Stereo Credit: Expedition 20 Crew - International Space Station, NASA Stereo Image: Patrick Vantuyne Explanation: From 400 kilometers above planet Earth, the Expedition 20 Crew onboard the International Space Station (ISS) was able to witness a remarkable event from a remarkable vantage point -- the June 12 eruption of the Sarychev Peak Volcano. The active volcano is located in Russia's Kuril Island chain, stretching to the northeast of Japan. Emphasizing the orbital perspective, this stunning color stereo view was made by combining two images from the ISS and is intended to be viewed with red/blue glasses...
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Molecular Cloud Barnard 68 Credit: FORS Team, 8.2-meter VLT Antu, ESO Explanation: Where did all the stars go? What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gas absorb practically all the visible light emitted from background stars. The eerily dark surroundings help make the interiors of molecular clouds some of the coldest and most isolated places in the universe. One of the most notable of these dark absorption nebulae is a cloud toward the constellation Ophiuchus known as Barnard 68,...
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Atlas 5 Rocket Launches to the Moon Credit: NASA Explanation: This rocket is headed for the Moon. Pictured above, a huge Altas V rocket roared off the launch pad last week to start NASA's first missions to Earth's Moon in 10 years. The rocket is carrying two robotic spacecraft. The Lunar Reconnaissance Orbiter (LRO) is scheduled to orbit and better map the Moon, search for buried and hidden ice, and return many high resolution images. Some images will be below one-meter in resolution and include images of historic Apollo landing sites. Exploratory data and images should allow a more informed...
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NGC 6240: Merging Galaxies Credit: NASA / JPL-Caltech / STScI-ESA / S. Bush, et al. (Harvard-Smithsonian CfA) Explanation: NGC 6240 offers a rare glimpse of a cosmic catastrophe in its final throes. The titanic galaxy-galaxy collision is located a mere 400 million light-years away in the constellation Ophiuchus. One of the brightest sources in the infrared sky, the merging galaxies spew distorted tidal tails of stars, gas, and dust and undergo frantic bursts of star formation. The two supermassive black holes in the original galactic cores will also coalesce into a single, even more massive black hole. Soon, only one...
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M13: A Great Globular Cluster of Stars Credit & Copyright: Danny Lee Russell Explanation: M13 is one of the most prominent and best known globular clusters. Visible with binoculars in the constellation of Hercules, M13 is frequently one of the first objects found by curious sky gazers seeking celestials wonders beyond normal human vision. M13 is a colossal home to over 100,000 stars, spans over 150 light years across, lies over 20,000 light years distant, and is over 12 billion years old. At the 1974 dedication of Arecibo Observatory, a radio message about Earth was sent in the direction...
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Streaming Dark Nebulas near B44 Credit & Copyright: Thomas V. Davis (tvdavisastropix.com) Explanation: Dark dust lit by the bright yellow star Antares highlight this photogenic starscape of the southern sky. A wider angle image shows the central band of our Milky Way Galaxy connected to Antares by streams of dust knows as the Dark River. At the head of the Dark River the dust appears in dense knots. One of the densest knots is B44, pictured near the bottom of the above image. Off to the left of the above image lies Antares, a star so bright that the pictured...
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Stars at the Galactic Center Credit: Susan Stolovy (SSC/Caltech) et al., JPL-Caltech, NASA Explanation: The center of our Milky Way Galaxy is hidden from the prying eyes of optical telescopes by clouds of obscuring dust and gas. But in this stunning vista, the Spitzer Space Telescope's infrared cameras, penetrate much of the dust revealing the stars of the crowded galactic center region. A mosaic of many smaller snapshots, the detailed, false-color image shows older, cool stars in bluish hues. Reddish glowing dust clouds are associated with young, hot stars in stellar nurseries. The very center of the Milky Way was...
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The Milky Road Credit & Copyright: Larry Landolfi Explanation: Inspired by the night skies of planet Earth in the International Year of Astronomy, photographer Larry Landolfi created this tantalizing fantasy view. The composited image suggests a luminous Milky Way is the heavenly extension of a country road. Of course, the name for our galaxy, the Milky Way (in Latin, Via Lactea), does refer to its appearance as a milky band or path in the sky. In fact, the word galaxy itself derives from the Greek for milk. Visible on moonless nights from dark sky areas, though not so bright or...
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SNR 0104: An Unusual Suspect Credit: X-ray: NASA / CXC / Penn State / S.Park & J.Lee; Infrared: NASA / JPL-Caltech Explanation: SNR 0104 is a supernova remnant with an unusual shape. Found 190,000 light-years away in our neighboring galaxy the Small Magellanic Cloud, SNR 0104 is suspected of being the expanding debris cloud from a Type 1a supernova - the catastrophic thermonuclear explosion of a white dwarf star. For example, like Type 1a supernova remnants within our galaxy, investigations show that it contains large amounts of iron. But unlike other Type 1a remnants, including the well-studied Tycho, Kepler, and...
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Pyrenees Paraselene Credit & Copyright: Patrick Lécureuil Explanation: A sea of clouds laps at rugged moutain peaks of the French Pyrenees in this serene view from Pic du Midi Observatory. The time exposure was recorded on June 4, with the constellations Sagittarius and Scorpius shining in the starry night. At the top right lies a faint, but colorful moondog or paraselene. Analogous to a sundog or parhelion, the paraselene is produced by moonlight shining through thin, hexagonal-shaped ice crystals in high cirrus clouds. As determined by the ice crystal geometry, a bright gibbous Moon illuminates the scene from beyond the...
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A Dusty Iris Nebula Credit & Copyright: Alvin Jeng (LightBuckets.com) Explanation: These clouds of interstellar dust and gas have blossomed 1,300 light-years away in the fertile star fields of the constellation Cepheus. Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023, this is not the only nebula in the sky to evoke the imagery of flowers. Surrounding it, obscuring clouds of dust and cold molecular gas are also present and can suggest other convoluted and fantastic shapes. Within the Iris, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue,...
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Markarian's Chain of Galaxies Credit & Copyright: Piotrek Sadowski Explanation: Across the heart of the Virgo Cluster of Galaxies lies a striking string of galaxies known as Markarian's Chain. The chain, pictured above, is highlighted on the upper right with two large but featureless lenticular galaxies, M84 and M86. Prominent to their lower left is a pair of interacting galaxies known as The Eyes. The home Virgo Cluster is the nearest cluster of galaxies, contains over 2000 galaxies, and has a noticeable gravitational pull on the galaxies of the Local Group of Galaxies surrounding our Milky Way Galaxy. The center...
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Possible Jet Blown Shells Near Microquasar Cygnus X-1 Credit & Copyright: Steve Cullen (lightbuckets.com) Explanation: What happens to matter that falls toward an energetic black hole? In the case of Cygnus X-1, perhaps little of that matter actually makes it in. Infalling gas may first collide not only with itself but with an accretion disk of swirling material surrounding the black hole. The result may be a microquasar that glows across the electromagnetic spectrum and produces powerful jets that expel much of the infalling matter back into the cosmos at near light speed before it can even approach the black...
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Asteroid Eros Reconstructed Credit: NEAR Project, NLR, JHUAPL, Goddard SVS, NASA Explanation: Orbiting the Sun between Mars and Earth, asteroid 433 Eros was visited by the robot spacecraft NEAR-Shoemaker in 2000 February. High-resolution surface images and measurements made by NEAR's Laser Rangefinder (NLR) have been combined into the above visualization based on the derived 3D model of the tumbling space rock. NEAR allowed scientists to discover that Eros is a single solid body, that its composition is nearly uniform, and that it formed during the early years of our Solar System. Mysteries remain, however, including why some rocks on the...
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One-Armed Spiral Galaxy NGC 4725 Credit & Copyright: Mike Siniscalchi Explanation: While most spiral galaxies, including our own Milky Way, have two or more spiral arms, NGC 4725 seems to have only one. In this sharp color image, the solo spira mirabilis is tightly wound, traced by bluish, newborn star clusters. The odd galaxy also sports obscuring dust lanes, a prominent ring, and a yellowish central bar structure composed of an older population of stars. NGC 4725 is over 100 thousand light-years across and lies 41 million light-years away in the well-groomed constellation Coma Berenices. Computer simulations of the formation...
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Stars and Dust Across Corona Australis Credit & Copyright: Andrey Oreshko Explanation: Cosmic dust clouds sprawl across a rich field of stars in this sweeping telescopic vista near the northern boundary of Corona Australis, the Southern Crown. Probably less than 500 light-years away and effectively blocking light from more distant, background stars in the Milky Way, the densest part of the dust cloud is about 8 light-years long. At its tip (upper right) is a group of lovely reflection nebulae cataloged as NGC 6726, 6727, 6729, and IC 4812. A characteristic blue color is produced as light from hot stars...
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Sunspots on a Cloudy Day Credit & Copyright: Stefan Seip (TWAN) Explanation: On June 2nd, clouds over Stuttgart, Germany parted to reveal what has become a relatively rare sight, spots on the Sun. In fact, the roughly 11-year solar activity cycle is still in a surprisingly deep minimum and the years 2008 and 2009 have had the lowest sunspot counts since the 1950s. Even the latest prediction is that the new cycle, Solar Cycle 24, will reach a maximum in May 2013 with a below-average sunspot count. The Solar Cycle 24 sunspots recorded here are in active region AR 1019....
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VB 10: A Large Planet Orbiting a Small Star Illustration Credit: JPL-Caltech, NASA Explanation: Can a planet be as large as the star that it orbits? Recent observations have discovered that nearby Van Biesbroeck's star might have just such a large planet. Although VB 10 lies only about 20 light years away, it is a small red dwarf star so dim, at 17th magnitude, that a telescope is needed to see it. Van Biesbroeck's star was previously known for its rapid proper motion across the sky -- it moves so fast it could cross a full moon in only about...
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Spokes Reappear on Saturn's Rings Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA Explanation: What causes the mysterious spokes in Saturn's rings? Visible in the above image as light ghostlike impressions, spokes were first discovered by the Voyager spacecraft that buzzed by Saturn in the early 1980s. Their existence was unexpected. Oddly, the spokes more commonly observed when Saturn's rings are more nearly edge on to the Sun, and so were conspicuously absent from initial images sent back by the robot Cassini spacecraft now orbiting Saturn. Analyses of archived Voyager images have led to the conclusions that the transient spokes,...
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Spirit Encounters Soft Ground on Mars Credit: Mars Exploration Rover Mission, JPL, NASA Explanation: Will Spirit be able to free itself from soft ground on Mars? The robotic Spirit rover currently rolling across Mars ran into unexpectedly soft ground last month while exploring the red planet. A worry is that the ground is so soft that Spirit won't be able to free itself, will have to stay put and thereafter study what it can from its current position near an unusual martian land feature named Home Plate. Pictured above, the front left wheel appears to be primarily digging itself in...
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A Solar Prominence from SOHO Credit: SOHO-EIT Consortium, ESA, NASA Explanation: How can gas float above the Sun? Twisted magnetic fields arching from the solar surface can trap ionized gas, suspending it in huge looping structures. These majestic plasma arches are seen as prominences above the solar limb. In 1999 September, this dramatic and detailed image was recorded by the EIT experiment on board the space-based SOHO observatory in the light emitted by ionized Helium. It shows hot plasma escaping into space as a fiery prominence breaks free from magnetic confinement a hundred thousand kilometers above the Sun. These awesome...
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Messier 106 Credit & Copyright: Ken Crawford (Rancho Del Sol Observatory) Explanation: Close to the Great Bear (Ursa Major) and surrounded by the stars of the Hunting Dogs (Canes Venatici), this celestial wonder was discovered in 1781 by the metric French astronomer Pierre Mechain. Later, it was added to the catalog of his friend and colleague Charles Messier as M106. Modern deep telescopic views reveal it to be an island universe -- a spiral galaxy around 30 thousand light-years across located only about 21 million light-years beyond the stars of the Milky Way. Along with a bright central core, this...
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Moon in the Mullica Credit & Copyright: Jerry Lodriguss (Catching the Light) Explanation: Still waters mimic a predawn sky along the eastern horizon in this peaceful scene. The picture was recorded on May 22nd from the banks of the Mullica River, in a forested region known as the Pine Barrens of southern New Jersey on the US east coast. Near the horizon at the left is an old Moon with its narrow, sunlit crescent. Mars is near picture center and brilliant Venus shines farther right. Like the terrestrial lights along the riverbank, the bright celestial beacons are all reflected in...
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Volcanic Terrain on Mercury Credit: MESSENGER, NASA, JHU APL, CIW Explanation: Why are many large craters on Mercury relatively smooth inside? Recent images from the robotic MESSENGER spacecraft that flew by Mercury last October show previously uncharted regions of Mercury that have large craters with an internal smoothness similar to the maria on Earth's own Moon. Therefore, like our Moon's maria, these craters on Mercury are thought to have been flooded by lava floes that are old but not as old as the surrounding more highly cratered surface. The above image mosaic of the western limb of Mercury was created...
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Whirlpool Galaxy Deep Field Credit & Copyright: Jon Christensen Explanation: Follow the handle of the Big Dipper away from the dipper's bowl, until you get to the handle's last bright star. Then, just slide your telescope a little south and west and you might find this stunning pair of interacting galaxies, the 51st entry in Charles Messier's famous catalog. Perhaps the original spiral nebula, the large galaxy with well defined spiral structure is also cataloged as NGC 5194. Its spiral arms and dust lanes clearly sweep in front of its companion galaxy (left), NGC 5195. The pair are about...
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Hubble Floats Free Credit: STS-125 Crew, NASA Explanation: Why put observatories in space? Most telescopes are on the ground. On the ground, you can deploy a heavier telescope and fix it more easily. The trouble is that Earth-bound telescopes must look through the Earth's atmosphere. First, the Earth's atmosphere blocks out a broad range of the electromagnetic spectrum, allowing a narrow band of visible light to reach the surface. Telescopes which explore the Universe using light beyond the visible spectrum, such as those onboard the Chandra X-ray Observatory, and the Fermi Gamma Ray Space Telescope need to be carried above...
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Carina Nebula Panorama from Hubble Credit: NASA, ESA, N. Smith (U. California, Berkeley) et al., and The Hubble Heritage Team (STScI/AURA) Explanation: In one of the brightest parts of Milky Way lies a nebula where some of the oddest things occur. NGC 3372, known as the Great Nebula in Carina, is home to massive stars and changing nebula. Eta Carinae, the most energetic star in the nebula, was one of the brightest stars in the sky in the 1830s, but then faded dramatically. The Keyhole Nebula, visible left the center, houses several of the most massive stars known and has...
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East of Antares Credit & Copyright: Yuri Beletsky (ESO) Explanation: East of Antares, dark markings sprawl through crowded star fields toward the center of our Milky Way Galaxy. Cataloged in the early 20th century by astronomer E. E. Barnard, the obscuring interstellar dust clouds include B59, B72, B77 and B78, seen in silhouette against the starry background. Here, their combined shape suggests a pipe stem and bowl, and so the dark nebula's popular name is the Pipe Nebula. The deep and expansive view was recorded in very dark Chilean skies. It covers a full 10 by 7 degree field in...
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IC 4592: A Blue Horsehead Credit & Copyright: Rogelio Bernal Andreo Explanation: This complex of beautiful, dusty reflection nebulae lies in the constellation Scorpius along the plane of our Milky Way Galaxy. Its overall outline suggests a horsehead in profile, though it covers a much larger region than the better known Horsehead Nebula of Orion. The star near the eye of the horse and the center of the 5 degree wide field, is embedded in blue reflection nebula IC 4592 over 400 light-years away. At that distance, the view spans nearly 40 light-years. The horse's gaze seems fixed on Beta...
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Sagittarius and the Central Milky Way Credit & Copyright: Robert Gendler (robgendlerastropics.com) Explanation: What does the center of our Milky Way Galaxy look like? In visible light, no one knows! It is not possible to see the Galactic center in light our eyes are sensitive to because the thick dust in the plane of our Galaxy obscures it. If one looks in the direction of our Galaxy's center - which is toward the constellation of Sagittarius - many beautiful wonders become apparent, though. Large dust lanes and star clouds dominate the picture. As many as 30 Messier Objects are...
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M97: The Owl Nebula Credit & Copyright: Keith Quattrocchi Explanation: The Owl Nebula is perched in the sky about 2,600 light-years away toward the bottom of the Big Dipper's bowl. Also cataloged as M97, the 97th object in Messier's well-known list, its round shape along with the placement of two large, dark "eyes" do suggest the face of a staring owl. One of the fainter objects in Messier's catalog, the Owl Nebula is a planetary nebula, the glowing gaseous envelope shed by a dying sun-like star as it runs out of nuclear fuel. In fact, the Owl Nebula offers an...
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Elusive Jellyfish Nebula Credit & Copyright: Gerhard Bachmayer Explanation: Normally faint and elusive, the Jellyfish Nebula is caught in this alluring wide-field telescopic view. Flanked by two yellow-tinted stars, Mu and Eta Geminorum, at the foot of a celestial twin, the Jellyfish Nebula is the brighter arcing ridge of emission with dangling tentacles right of center. In fact, the cosmic jellyfish is seen to be part of bubble-shaped supernova remnant IC 443, the expanding debris cloud from a massive star that exploded. Light from the explosion first reached planet Earth over 30,000 years ago. Like its cousin in astrophysical waters...
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A Space Shuttle Before Dawn Credit & Copyright: Charles Danforth (CASA, U. Colorado) Explanation: This shuttle has launched to space. Pictured above, the Space Shuttle Atlantis sat on Launch Pad 39A before dawn last month as it was prepared for the launch. The shuttle itself is visible on the image right, attached to a brown liquid fuel tank and two white solid rocket boosters. In the image center is the Fixed Service Structure which stands just over 100 meters tall, including the white lightning rod at the top. Starting on Sunday, the space shuttle embarked on one of its most...
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Galaxies of the Perseus Cluster Credit & Copyright: R. Jay Gabany Explanation: This colorful telescopic skyscape is filled with galaxies that lie nearly 250 million light-years away, the galaxies of the Perseus cluster. Their extended and sometimes surprising shapes are seen beyond a veil of foreground stars in our own Milky Way. Ultimately consisting of over a thousand galaxies, the cluster is filled with yellowish elliptical and lenticular galaxies, like those scattered throughout this view of the cluster's central region. Notably, at the large galaxy at the left is the massive and bizarre-looking NGC 1275. A prodigious source of high-energy...
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Halo for NGC 6164 Credit & Copyright: Don Goldman Explanation: Beautiful emission nebula NGC 6164 was created by a rare, hot, luminous O-type star, some 40 times as massive as the Sun. Seen at the center of the cosmic cloud, the star is a mere 3 to 4 million years old. In another three to four million years the massive star will end its life in a supernova explosion. Spanning around 4 light-years, the nebula itself has a bipolar symmetry. That makes it similar in appearance to more familiar planetary nebulae - the gaseous shrouds surrounding dying sun-like stars....
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Titan Beyond the Rings Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA Explanation: When orbiting Saturn, be sure to watch for breathtaking superpositions of moons and rings. One such picturesque vista was visible recently to the robot Cassini spacecraft now orbiting Saturn. In 2006 April, Cassini captured Saturn's A and F rings stretching in front of cloud-shrouded Titan. Near the rings and appearing just above Titan was Epimetheus, a moon which orbits just outside the F ring. The dark space in the A ring is called the Encke Gap, although several thin knotted ringlets and even the small moon Pan...
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Rembrandt Impact Basin on Mercury Credit & Copyright: NASA/JHU APS/ASU/CIW; Courtesy Science/AAAS Explanation: Why do portions of this huge crater on Mercury have so much iron? The unusual Rembrandt impact basin was discovered recently in images taken during the robotic MESSENGER spacecraft's 2008 October flyby of the Solar System's innermost planet. The unusual Rembrandt spans over 700 kilometers and at 4 billion years old is possibly the youngest large impact basin on the planet. Multicolored images of the crater floor, however, indicate reflections from areas containing unusually high amounts of iron and titanium. These elements indicate that some exposed materials...
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The Eskimo Nebula from Hubble Credit: Andrew Fruchter (STScI) et al., WFPC2, HST, NASA Explanation: In 1787, astronomer William Herschel discovered the Eskimo Nebula. From the ground, NGC 2392 resembles a person's head surrounded by a parka hood. In 2000, the Hubble Space Telescope imaged the Eskimo Nebula. From space, the nebula displays gas clouds so complex they are not fully understood. The Eskimo Nebula is clearly a planetary nebula, and the gas seen above composed the outer layers of a Sun-like star only 10,000 years ago. The inner filaments visible above are being ejected by strong wind of particles...
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The Whale Galaxy Credit & Copyright: Adam Block, Mt. Lemmon SkyCenter, U. Arizona Guest Astronomers: Tom Bash and Craig Gates Explanation: NGC 4631 is a big beautiful spiral galaxy. Seen edge-on, it lies only 25 million light-years away in the well-trained northern constellation Canes Venatici. The galaxy's slightly distorted wedge shape suggests to some a cosmic herring and to others its popular moniker, The Whale Galaxy. Either way, it is similar in size to our own Milky Way. In this gorgeous color image, the galaxy's yellowish core, dark dust clouds, bright blue star clusters, and red star forming regions are...
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Lyrid Meteor and Milky Way Credit & Copyright: Tony Rowell / Astrophotostore.com Explanation: On April 22nd, the Lyrid Meteor Shower visited planet Earth's sky, an annual shower produced as the Earth plows through dust from the tail of comet Thatcher. Usually Lyrid meteor watchers see only a drizzle. Just a few meteors per hour stream away from the shower's radiant point near bright star Vega in the constellation Lyra. But photographer Tony Rowell still managed to catch one bright Lyrid meteor. Recorded in early morning hours, his well-composed image looks toward the south from White Mountains of eastern California, USA....
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GRB 090423: The Farthest Explosion Yet Measured Credit: Gemini Observatory / NSF / AURA, D. Fox & A. Cucchiara (Penn State U.), and E. Berger (Harvard Univ.) Explanation: An explosion so powerful it was seen clear across the visible universe was recorded in gamma-radiation last week by NASA's orbiting Swift Observatory. Farther than any known galaxy, quasar, or optical supernova, the gamma-ray burst recorded last week was clocked at redshift 8.2, making it the farthest explosion of any type yet detected. Occurring only 630 million years after the Big Bang, GRB 090423 detonated so early that astronomers had no direct...
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NGC 4565: Galaxy on the Edge Credit & Copyright: Roth Ritter (Dark Atmospheres) Explanation: Is our Galaxy this thin? We believe so. Magnificent spiral galaxy NGC 4565 is likely similar to our own spiral galaxy, but viewed edge-on from far away. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky as it lies in the faint but well-groomed constellation Coma Berenices. This sharp color image reveals the galaxy's bulging central core dominated by light from a population of older, yellowish stars. The core is dramatically...
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Prometheus Creating Saturn Ring Streamers Credit: Cassini Imaging Team, ISS, JPL, ESA, NASA Explanation: What's causing those strange dark streaks in the rings of Saturn? Prometheus. Specifically, an orbital dance involving Saturn's moon Prometheus keeps creating unusual light and dark streamers in the F-Ring of Saturn. Now Prometheus orbits Saturn just inside the thin F-ring, but ventures into its inner edge about every 15 hours. Prometheus' gravity then pulls the closest ring particles toward the 100-km moon. The result is not only a stream of bright ring particles but also a dark ribbon where ring particles used to be. Since...
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NGC 4676: When Mice Collide Credit: ACS Science & Engineering Team, Hubble Space Telescope, NASA Explanation: These two mighty galaxies are pulling each other apart. Known as "The Mice" because they have such long tails, each spiral galaxy has likely already passed through the other. They will probably collide again and again until they coalesce. The long tails are created by the relative difference between gravitational pulls on the near and far parts of each galaxy. Because the distances are so large, the cosmic interaction takes place in slow motion -- over hundreds of millions of years. NGC 4676 lies...
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