Active Region 1002 on an Unusually Quiet Sun Credit: SOHO Consortium, EIT, ESA, NASA Explanation: Why has the Sun been so quiet recently? No one is sure. Our Sun has shown few active regions -- that house even fewer associated sunspots -- for over a year now, and such a period of relative calm is quite unusual. What is well known is that our Sun is in a transitional period between solar cycles called a Solar Minimum, where solar activity has historically been reduced. The stark lack of surface tumult is unusual even during a Solar Minimum, however, and activity this low has not been seen for many decades. A few days ago, however, a bona-fide active region -- complete with sunspots --appeared and continues to rotate across the Sun's face. Visible above, this region, dubbed Active Region 1002 (AR 1002), was imaged in ultraviolet light yesterday by the SOHO spacecraft, which co-orbits the Sun near the Earth. Besides the tranquility on the Sun's surface, recent data from the Ulysses spacecraft, across the Solar System, indicate that the intensity of the solar wind blowing out from the Sun is at a fifty year low. Predictions hold, however, that our Sun will show more and more active regions containing more and more sunspots and flares until Solar Maximum occurs in about four years.
The Case of the Very Dusty Binary Star Illustration Credit & Copyright: Lynette Cook Explanation: For astronomers, close binary star system BD+20 307 originally stood out because it is extremely dusty. A substantial amount of warm dust surrounding it causes the system to appear exceptionally bright at infrared wavelengths. Of course, dust associated with planet formation is often detected around young stars, stars only a few million years old. But the BD+20 307 system has now been found to be at least a few billion years old, an age comparable to the age of our own Solar System. The large amount of warm dust is likely the debris from a relatively recent collision of planet-sized objects on the scale of, say, Earth and Venus, in the BD+20 307 system. Reminiscent of the classic scifi novel When Worlds Collide, the dramatic illustration offers a depiction of the catastrophic event. Ironically, this indirect evidence of a destructive planetary collision could also be the first indication that planetary systems can form around close binary stars. BD+20 307 is about 300 light-years distant toward the headstrong constellation Aries.
M83: The Thousand-Ruby Galaxy Color Composite: Davide De Martin (Skyfactory) Credit: European Southern Observatory Science Archive Explanation: 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. Prominent spiral arms traced by dark dust lanes and blue star clusters lend this galaxy its popular name of the Southern Pinwheel. But reddish star forming regions that dot the sweeping arms highlighted in this sparkling color composite also suggest another nickname, The Thousand-Ruby Galaxy. About 40,000 light-years across, M83 is a member of a group of galaxies that includes active galaxy Centaurus A. The core of M83 itself is bright at x-ray energies, showing a high concentration of neutron stars and black holes left from an intense burst of star formation. The sharp image, based on archival data from the European Southern Observatory's Wide Field Imager camera, also features spiky foreground Milky Way stars and distant background galaxies.
Young Stars of NGC 346 Credit: Antonella Nota (ESA/STScI) et al., ESA, NASA NASA Explanation: The massive stars of NGC 346 are short lived, but very energetic. The star cluster is embedded in the largest star forming region in the Small Magellanic Cloud, some 210,000 light-years distant. Their winds and radiation sweep out an interstellar cavern in the gas and dust cloud about 200 light-years across, triggering star formation and sculpting the region's dense inner edge. Cataloged as N66, the star forming region also appears to contain a large population of infant stars. A mere 3 to 5 million years old and not yet burning hydrogen in their cores,the infant stars are strewn about the embedded star cluster. In the above false-color Hubble Space Telescope image, visible and near-infrared light are seen as blue and green, while light from atomic hydrogen emission is red.
NGC 253 Close-Up Credit: NASA, ESA, J. Dalcanton, B. Williams (Univ. Washington) Ground-based data: T. Rector (Univ. Alaska, Anchorage), T. Abbott, NOAO/AURA/NSF Explanation: This dusty island universe is one of the brightest spiral galaxies in the sky. Seen nearly edge-on, NGC 253 lies a mere 13 million light-years away and is the largest member of the Sculptor Group of galaxies, neighbor to our own local galaxy group. The remarkably sharp, close-up view is based on data from the Hubble's Advanced Camera for Surveys (ACS). Beginning on the left near the galaxy's core, the panorama follows filaments of dust, interstellar gas, and even individual stars toward the galaxy's edge at the far right, a magnificent vista spanning nearly 50,000 light-years. The image data are part of ANGST, the ACS Nearby Galaxy Survey Treasury, a program to explore our cosmic backyard.
Young Suns of NGC 7129 Credit & Copyright: Bob and Janice Fera (Fera Photography) Explanation: Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only about a million years old, it is likely that our own Sun formed in a similar stellar nursery some five billion years ago. Most noticeable in the striking image are the lovely bluish dust clouds that reflect the youthful starlight, but the smaller, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color is characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. At the estimated distance of NGC 7129, this telescopic view spans about 40 light-years.
A Solar Prominence Unfurls Credit: STEREO Project, NASA Explanation: On September 29, this magnificent eruptive solar prominence lifted away from the Sun's surface, unfurling into space over the course of several hours. Suspended in twisted magnetic fields, the hot plasma structure is many times the size of planet Earth and was captured in this view by the Sun-watching STEREO (Ahead) spacecraft. The image was recorded in extreme ultraviolet light emitted by ionized Helium, an element originally identified in the solar spectrum. Seen against the brilliant solar surface in visible light, such prominences appear as dark filaments because they are relatively cool. But they are bright themselves when viewed against the blackness of space, arcing above the Sun's edge. A video of the eruption (a 2.6MB .mov file) is available here.
Cool.. a nice vally for my tent.. Layers of Red Cliffs on Mars Credit: HiRISE, MRO, LPL (U. Arizona), NASA Explanation: How did these layers of red cliffs form on Mars? No one is sure. The northern ice cap on Mars is nearly divided into two by a huge division named Chasma Boreale. No similar formation occurs on Earth. Pictured above, several dusty layers leading into this deep chasm are visible. Cliff faces, mostly facing left but still partly visible from above, appear dramatically red. The light areas are likely water ice. The above image spans about one kilometer near the north of Mars, and the elevation drop from right to left is over a kilometer. One hypothesis relates the formation of Chasma Boreale to underlying volcanic activity.
Dust Mountains in the Carina Nebula Credit: NASA, ESA, Hubble Heritage (STScI/AURA); Acknowledgement: N. Smith et al. (JHU) Explanation: Bright young stars sometimes sculpt picturesque dust mountains soon after being born. Created quite by accident, the energetic light and winds from these massive newborn stars burn away accumulations of dark dust and cool gas in a slow but persistent manner. Such is the case in NGC 3324, a star forming region near the edge of NGC 3372, the energetic and expansive Carina Nebula. Pictured above, in scientifically assigned colors, is only a small part of NGC 3324. The Carina Nebula itself is one of the largest star forming regions known and home to Eta Carinae, one of the most unstable and variable stars known. The above image was created from archived Hubble Space Telescope data in honor of the 10th anniversary of the Hubble Heritage Project. The Hubble Heritage Project has created, so far, nearly 130 visually stunning images.
Mercury as Revealed by MESSENGER Credit: MESSENGER, NASA, JHU APL, CIW Explanation: The planet Mercury has been known since history has been recorded, but parts of the Solar System's innermost planet have never been seen like this before. Two days ago the robotic MESSENGER spacecraft buzzed past Mercury for the second time and imaged terrain mapped previously only by comparatively crude radar. The above image was recorded as MESSENGER looked back 90 minutes after passing, from an altitude of about 27,000 kilometers. Visible in the above image, among many other newly imaged features, are unusually long rays that appear to run like meridians of longitude out from a young crater near the northern limb. MESSENGER is scheduled to fly past Mercury once more before firing its thrusters to enter orbit in 2011.
Massive Stars in NGC 6357 Credit & Copyright: Johannes Schedler (Panther Observatory) Explanation: Massive Stars lie within NGC 6357, an expansive emission nebula complex some 8,000 light-years away in the tail of the constellation Scorpius. In fact, positioned just below center in this close-up view of NGC 6357, star cluster Pismis 24 includes some of the most massive stars known in the galaxy, stars with over 100 times the mass of the Sun. The nebula's bright central region also contains dusty pillars of molecular gas, likely hiding massive protostars from the prying eyes of optical instruments. Intricate shapes in the nebula are carved by interstellar winds and energetic radiation from the young and newly forming massive stars. This alluring telescopic view spans just under 50 light-years at the estimated distance of NGC 6357.
Irregular Galaxy NGC 55 Credit & Copyright: Robert Gendler Explanation: Irregular galaxy NGC 55 is thought to be similar to the Large Magellanic Cloud (LMC). But while the LMC is about 180,000 light-years away and is a well known satellite of our own Milky Way Galaxy, NGC 55 is more like 6 million light-years distant and is a member of the Sculptor Galaxy Group. Classified as an irregular galaxy, in deep exposures the LMC itself resembles a barred disk galaxy. However, spanning about 50,000 light-years, NGC 55 is seen nearly edge-on, presenting a flattened, narrow profile in contrast with our face-on view of the LMC. Just as large star forming regions create emission nebulae in the LMC, NGC 55 is also seen to be producing new stars. This gorgeous galaxy portrait highlights a bright core, telltale pinkish emission regions, and young blue star clusters in NGC 55.
Bright Bolide Credit & Copyright: Howard Edin (Oklahoma City Astronomy Club) Explanation: On September 30, a spectacular bolide or fireball meteor surprised a group of amateur astronomers enjoying dark night skies over the Oklahoma panhandle's Black Mesa State Park in the Midwestern US. Flashing past familiar constellations Taurus (top) and Orion, the extremely bright meteor was captured by a hillside camera overlooking the 2008 Okie-Tex Star Party. Astronomy enthusiast Howard Edin reports that he was looking in the opposite direction at the time, but saw the whole observing field light up and at first thought someone had turned on their car headlights. So far the sighting of a such a bright bolide meteor, produced as a space rock is vaporized hurtling through Earth's atmosphere, really is a matter of luck. But that could change. Earlier this week the discovery and follow-up tracking of tiny asteroid 2008 TC3 allowed astronomers to predict the time and location of its impact with the atmosphere. While no ground-based sightings of the fireball seem to have been reported, this first ever impact prediction was confirmed by at least some detections of an air burst and bright flash on October 7th over northern Sudan.
Cassini Passes Through Ice Plumes of Enceladus Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA Explanation: What telling impurities taint the ice plumes of Enceladus? To help answer this question, the robotic Cassini spacecraft dove last week to within 30 kilometers of Saturn's ice-plume emitting moon. At this closest-ever approach, Cassini attempted to sniff and obtain chemical data on particles ejected from Enceladus' regular surface, while at other times Cassini flew right through -- and sampled -- ice geysers directly. Searches in the data for impurity clues in the water-ice dominated plumes and surface ejecta are progressing. Although the main purpose of this flyby was particle analysis, several interesting images are emerging. Visible in the above image, for example, is an unusual gray sheen running vertically up the image center that might be water vapor escaping from surface canyons. Other notable features visible above include vast plains of craterless icy grooves, the day-night terminator across the image left, and an area near the top comparatively rich in craters. Cassini is scheduled to buzz by Enceladus in an imaging run near the end of this month.
Camera Orion Credit & Copyright: John Gauvreau Explanation: Orion, the Hunter, is one of the most easily recognizable constellations in planet Earth's night sky. But Orion's stars and nebulas don't look quite as colorful to the eye as they do in this lovely camera image, taken early last month at the Black Forest Star Party from Cherry Springs State Park in Pennsylvania, USA. In this single exposure, cool red giant Betelgeuse takes on a yellowish tint as the brightest star at the far left. Otherwise Orion's hot blue stars are numerous, with supergiant Rigel balancing Betelgeuse at the upper right, Bellatrix at the upper left, and Saiph at the lower right. Lined up in Orion's belt (bottom to top) are Alnitak, Alnilam, and Mintaka all about 1,500 light-years away, born of the constellation's well studied interstellar clouds. And if the middle "star" of Orion's sword looks reddish and fuzzy to you, it should. It's the stellar nursery known as the Great Nebula of Orion.
Wow... I mean... wow. Sharpless 171 Credit & Copyright: Antonio Fernandez Explanation: Cosmic pillars of cold molecular gas and clouds of dark dust lie within Sharpless 171, a star-forming region some 3,000 light-years away in the royal constellation Cepheus. This tantalizing false-color skyscape spans about 20 light-years across the nebula's bright central region. It also highlights the pervasive glow of emission from atomic gas using narrowband filters and a color palette made popular in Hubble Space Telescope images. Powering the nebular glow are the young, hot stars of a newly formed cluster, Berkeley 59. Of course, this star-forming region is entry number 171 in the famous 1959 catalog of emission nebulae compiled by astronomer Stewart Sharpless.
unfeakingbelievable.. beautiful In the Center of the Lagoon Nebula Credit: A. Caulet (ST-ECF, ESA), NASA Explanation: The center of the Lagoon Nebula is a whirlwind of spectacular star formation. Visible on the upper left, at least two long funnel-shaped clouds, each roughly half a light-year long, have been formed by extreme stellar winds and intense energetic starlight. The tremendously bright nearby star, Hershel 36, lights the area. Vast walls of dust hide and redden other hot young stars. As energy from these stars pours into the cool dust and gas, large temperature differences in adjoining regions can be created generating shearing winds which may cause the funnels. This picture, spanning about 5 light years, was taken in 1995 by the orbiting Hubble Space Telescope. The Lagoon Nebula, also known as M8, lies about 5000 light years distant toward the constellation of Sagittarius.
Moons, Rings, and Unexpected Colors on Saturn Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA Explanation: Why would Saturn show such strange colors? The robotic Cassini spacecraft currently orbiting Saturn has beamed back images showing that the northern hemisphere our Solar System's most spectacularly ringed planet has changed noticeably since Cassini arrived in 2004, now sporting unusual and unexpected colors. No one is sure why. Although the cause for many of Saturn's colors is unknown, the recent change in colors is thought to be related to the changing seasons. Pictured above, the unusual colors are visible just north of the dark ring shadows. The razor-thin plane of ring particles is visible nearly edge-on across the bottom of the image. The cloudy moon Titan looms large just above the rings, while close observation will reveal three other moons. Cassini arrived at Saturn in 2004, sending back data and images that have not only led to a deeper understanding of the Jovian world's atmosphere, moons, and rings, but also raised new mysteries.
Beautiful Spiral NGC 7331 Credit & Copyright: Vicent Peris (OAUV / PTeam), Gilles Bergond, Calar Alto Observatory. Explanation: A favorite target for astronomers, big, beautiful spiral galaxy NGC 7331 is one of the brighter galaxies not found in Charles Messier's famous 18th century catalog. About 50 million light-years distant in the northern constellation Pegasus and similar in size to our own Milky Way Galaxy, NGC 7331 is often imaged as the foreground of a visual grouping that includes an intriguing assortment of background galaxies some ten times farther away. This striking image of the well-studied island universe and environs was produced using data from the Calar Alto Observatory in southern Spain. Perhaps the deepest view of the region yet, the image data were processed to reveal sharp details of all sizes in both bright and faint areas. A color balance was chosen so that white would be the result of averaging colors over the entire galaxy. The result shows off a wealth of remarkable features in NGC 7331 and its surroundings.
Great Orion Nebulae Credit & Copyright: Tony Hallas Explanation: The Great Nebula in Orion, also known as M42, is one of the most famous nebulae in the sky. The star forming region's glowing gas clouds and hot young stars are on the right in this sharp and colorful two frame mosaic that includes the smaller nebula M43 near center and dusty, bluish reflection nebulae NGC 1977 and friends on the left. Located at the edge of an otherwise invisible giant molecular cloud complex, these eye-catching nebulae represent only a small fraction of this galactic neighborhood's wealth of interstellar material. Within the well-studied stellar nursery, astronomers have also identified what appear to be numerous infant solar systems. The gorgeous skyscape spans nearly two degrees or about 45 light-years at the Orion Nebula's estimated distance of 1,500 light-years.
