Galaxies
A galaxy is a principal component of our universe. It is made up of stars, an interstellar medium of gas and dust and a large number of stars, ranging from a few tens of million to as many as a trillion. Stars may congregate in clusters, associations and in spiral arms. Galaxies are also thought to contain vast amounts of dark matter, extending beyond the distribution of stars. Galaxies are held together by gravity including that due to the dark matter. Most galaxies are 1,000 to 100,000 parsecs (3000 to 300,000 light-years) in diameter and are usually separated by distances on the order of millions of parsecs. There are about 100 billion galaxies in the visible Universe. When capitalized, Galaxy refers to our own Milky Way Galaxy.
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Featured News
Dense Gas in Ultraluminous Infrared Galaxies
CAMBRIDGE, MA (Jan. 18, 2010) – Ultraluminous infrared galaxies have luminosities that exceed a trillion suns. (For comparison, the Milky Way's luminosity is only that of... More »
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Featured News
Black hole zapping a galaxy into existence
GARCHING, GERMANY (Nov. 30, 2009) – Which comes first, the supermassive black holes that frantically devour matter or the enormous galaxies where they reside? A brand new... More »
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Baffling Galactic Bulge
GARCHING, GERMANY (Nov. 18, 2009) – Just as many people are surprised to find themselves packing on unexplained weight around the middle, astronomers find the evolution of... More »
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'Dropouts' Pinpoint Earliest Galaxies
PASADENA, CA (Nov. 9, 2009) – Astronomers, conducting the broadest survey to date of galaxies from about 800 million years after the Big Bang, have found 22 early galaxies... More »
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X-ray Jets from Galaxies
Harvard-Smithsonian Center for Astrophysics (Oct. 22, 2009) – Some dramatic galaxies eject gigantic, collimated jets of ionized gas millions of light-years long, powered... More »
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Ram Pressure Stripping Galaxies, Hubble Space...
ESA/Hubble, Garching, Germany (Sep. 30, 2009) – A newly released set of images, taken by the NASA/ESA Hubble Space Telescope before the recent Servicing Mission, highlight the... More »
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Featured News
NGC 4945: The Milky Way's not-so-distant Cousin
European Southern Observatory, Garching (Sep. 2, 2009) – ESO has released a striking new image of a nearby galaxy that many astronomers think closely resembles our own Milky... More »
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Featured News
Galaxies Demand a Stellar Recount
NASA JPL, Pasadena, CA (Aug. 20, 2009) – For decades, astronomers have gone about their business of studying the cosmos with the assumption that stars of certain sizes form in... More »
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Featured News
Mysterious Space Blob Discovered at Cosmic Dawn
Carnegie Institution for Science (Apr. 23, 2009) – Using information from a suite of telescopes, astronomers have discovered a mysterious, giant object that existed at a time... More »
ESO Very Large Telescope Shows Spectacular Spiral...
Last Updated on 2011-08-16 at 17:45
ESO, Garching, Germany (10 Aug. 2011) – This new picture from ESO’s Very Large Telescope shows NGC 3521, a spiral galaxy located about 35 million light years away in... More »
Dense Gas in Ultraluminous Infrared Galaxies
Last Updated on 2010-01-18 at 13:59
CAMBRIDGE, MA (Jan. 18, 2010) – Ultraluminous infrared galaxies have luminosities that exceed a trillion suns. (For comparison, the Milky Way's luminosity is only that of... More »
Black hole zapping a galaxy into existence
Last Updated on 2009-11-30 at 11:27
GARCHING, GERMANY (Nov. 30, 2009) – Which comes first, the supermassive black holes that frantically devour matter or the enormous galaxies where they reside? A brand new... More »
Baffling Galactic Bulge
Last Updated on 2009-11-19 at 17:01
GARCHING, GERMANY (Nov. 18, 2009) – Just as many people are surprised to find themselves packing on unexplained weight around the middle, astronomers find the evolution of... More »
Radio Galaxies: Early Universe
Last Updated on 2009-11-11 at 17:09
Radio galaxies are cosmic beacons, with the brightest ones beaming nearly a trillion solar-luminosities of radiation into space at radio wavelengths. The origin of this intense... More »
Seven Billion Year-old Galaxies
Last Updated on 2009-11-11 at 16:28
As modern telescopes peer more and more deeply into the universe, they are seeing older and older galaxies. The current record is a galaxy whose light has been traveling towards... More »
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