NGC 922: Collisional Ring Galaxy
Why does this galaxy have so many big black holes? No one is sure. What is sure is that NGC 922 is a ring galaxy created by the collision of a large and small galaxy about 300 million years ago.
Image Credit: NASA, ESA; Acknowledgement: Nick Rose
Like a rock thrown into a pond, the ancient collision sent ripples of high density gas out from the impact point near the center that partly condensed into stars. Pictured above is NGC 922 with its beautifully complex ring along the left side, as imaged recently by the Hubble Space Telescope. Observations of NGC 922 with the Chandra X-ray Observatory, however, show several glowing X-ray knots that are likely large black holes.
The high number of massive black holes was somewhat surprising as the gas composition in NGC 922 — rich in heavy elements — should have discouraged almost anything so massive from forming. Research is sure to continue. NGC 922 spans about 75,000 light years, lies about 150 million light years away, and can be seen with a small telescope toward the constellation of the furnace (Fornax).
NGC 206 and the Star Clouds of Andromeda
The large stellar association cataloged as NGC 206 is nestled within the dusty arms of neighboring spiral galaxy Andromeda (M31), 2.5 million light-years distant.
Seen near the center of this gorgeous close-up of the southwestern extent of Andromeda’s disk, the bright, blue stars of NGC 206 indicate its youth. Its youngest massive stars are less than 10 million years old.
Much larger than the clusters of young stars in the disk of our Milky Way galaxy known as open or galactic clusters, NGC 206 spans about 4,000 light-years. That’s comparable in size to the giant stellar nurseries NGC 604 in nearby spiral M33 and the Tarantula Nebula, in the Large Magellanic Cloud.
A single image from the world’s most powerful survey instrument captured this spectacular skyview.
Looking toward Sagittarius, the scene spans nearly 3 degrees or six times the width of the Full Moon. At bottom, upper right, and lower left it covers the Lagoon Nebula (M8), the Trifid Nebula (M20), and NGC 6559, in the crowded, dusty starfields of the central Milky Way.
The adopted color scheme shows dust reddened starlight in red hues and normally red emission from hydrogen atoms in green. Built and operated by the Pan-STARRS project, the instrument features a 1.4 gigapixel (billion pixel) digital camera and telescope.
Pan-STARRS, the Panoramic Survey Telescope & Rapid Response System, is intended to scan the skies for potentially dangerous near-earth asteroids and comets, exploring the Universe with a unique high resolution, wide field view.
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The outer shells of Centaurus A
Spiral Galaxy NGC 4038 in Collision
Image Credit: Data Collection: Hubble Legacy Archive; Processing: Danny Lee Russell
This galaxy is having a bad millennium. In fact, the past 100 million years haven’t been so good, and probably the next billion or so will be quite tumultuous.
Visible on the upper left, NGC 4038 used to be a normal spiral galaxy, minding its own business, until NGC 4039, toward its right, crashed into it. The evolving wreckage, known famously as the Antennae, is pictured above. As gravity restructures each galaxy, clouds of gas slam into each other, bright blue knots of stars form, massive stars form and explode, and brown filaments of dust are strewn about.
Eventually the two galaxies will converge into one larger spiral galaxy. Such collisions are not unusual, and even our own Milky Way Galaxy has undergone several in the past and is predicted to collide with our neighboring Andromeda Galaxy in a few billion years. The frames that compose this image were taken by the orbiting Hubble Space Telescope by professional astronomers to better understand galaxy collisions.
These frames — and many other deep space images from Hubble — have since been made public, allowing an interested amateur to download and process them into this visually stunning composite.
High Energy Stereoscopic System II
The largest of its kind, the High Energy Stereoscopic System (H.E.S.S.) II telescope stands in the foreground of this photo.
Tilted horizontally it reflects the inverted landscape of the Namibian desert in a segmented mirror 24 meters wide and 32 meters tall, equal in area to two tennis courts.
Now beginning an exploration of the Universe at extreme energies, H.E.S.S. II saw first light on July 26. Most ground-based telescopes with lenses and mirrors are hindered by the Earth’s nurturing, protective atmosphere that blurs images and scatters and absorbs light.
But the H.E.S.S. II telescope is a cherenkov telescope, designed to detect gamma rays - photons with over 100 billion times the energy of visible light - and actually requires the atmosphere to operate. As the gamma rays impact the upper atmosphere they produce air showers of high-energy particles.
A large camera at the mirror’s focus records in detail the brief flashes of optical light, called cherenkov light, created by the air shower particles. The H.E.S.S. II telescope operates in concert with the array of four other 12 meter cherenkov telescopes to provide multiple stereoscopic views of the air showers, relating them to the energies and directions of the incoming cosmic gamma rays.
Enceladus Backlit by Saturn
Image Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA; Color Composite: Gordan Ugarkovic
This moon is shining by the light of its planet. Specifically, a large portion of Enceladus pictured above is illuminated primarily by sunlight first reflected from the planet Saturn. The result is that the normally snow-white moon appears in the gold color of Saturn’s cloud tops.
As most of the illumination comes from the image left, a labyrinth of ridges throws notable shadows just to the right of the image center, while the kilometer-deep canyon Labtayt Sulci is visible just below. The bright thin crescent on the far right is the only part of Enceladus directly lit by the Sun.
The above image was taken last year by the robotic Cassini spacecraft during a close pass by by the enigmatic moon. Inspection of the lower part of this digitally sharpened image reveals plumes of ice crystals thought to originate in a below-surface sea.
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Through a Sun Tunnel
Today the Sun stands still at 05:30 UT. Halting its steady march toward southern declinations and begining its annual journey north, the event is known as a solstice. In the northern hemisphere December’s solstice marks the astronomical start of winter. And if you’re in the Great Basin Desert outside of Lucin, Utah, USA, near solstice dates you can watch the Sun rise and set through Sun Tunnels.
A monumental earthwork by artist Nancy Holt, the Sun Tunnels are constructed of four 9 foot diameter cast concrete pipes each 18 feet long. The tunnels are arranged in a wide X to achieve the solstitial sunset and sunrise alignments. In this dramatic snapshot through a Sun Tunnel the Sun is just on the horizon. The cold, cloudy sunset was near the 2010 winter solstice.
During daylight hours, holes in the sides of the pipes project spots of sunlight on their interior walls, forming a map of the principal stars in the constellations Draco, Perseus, Columba, and Capricorn. Fans of planet earthworks and celestial landart should note that the Sun Tunnels are about 150 miles by car from Robert Smithson’s (Holt’s late husband) Spiral Jetty.
Image Credit & Copyright: Arne Erisoty
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Starburst Galaxy IC 10
Lurking behind dust and stars near the plane of our Milky Way Galaxy, IC 10 is a mere 2.3 million light-years distant.
Even though its light is dimmed by intervening dust, the irregular dwarf galaxy still shows off vigorous star-forming regions that shine with a telltale reddish glow in this colorful skyscape.
Image Credit & Copyright: Dietmar Hager, Torsten Grossmann
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Lunar Eclipse Over an Indian Peace Pagoda
Our Moon turned red last week. The reason was that during December 10, a total lunar eclipse occurred. The above digitally superimposed image mosaic captured the Moon many times during the eclipse, from before the Moon entered Earth’s shadow until after the Moon exited.
The image sequence was recorded over a Shanti Stupa Peace Pagota near the center of New Delhi, India, where the eclipse of the Moon was nearly, but not completely, total.
The red tint of the eclipsed Moon was created by sunlight first passing through the Earth’s atmosphere, which preferentially scatters blue light (making the sky blue) but passes and refracts red light, before reflecting back off the Moon. Differing amounts of clouds and volcanic dust in the Earth’s atmosphere make each lunar eclipse appear differently. The next total lunar eclipse will occur only in 2014.
Image Credit & Copyright: Chander Devgun (SPACE)
