Wednesday, July 11, 2012

Ghost Galaxies

The Hubble Space Telescope has captured images of three odd galaxies that may help scientists solve a 13 billion-year cosmic mystery.
The galaxies are so old and faint that astronomers nicknamed them "ghost galaxies" in a description. The objects are among the smallest and faintest galaxies near our own Milky Way galaxy, researchers said.
 "These galaxies are fossils of the early universe: they have barely changed for 13 billion years," scientists explained in a July 10 announcement. "The discovery could help explain the so-called 'missing satellite' problem, where only a handful of satellite galaxies have been found around the Milky Way, against the thousands that are predicted by theories."

The three galaxies observed by the Hubble telescope are known as Hercules, Leo IV and Ursa Major. All three objects are small dwarf galaxies that appear to have begun forming about 13 billion years ago and then — for an unknown reason — their growth hit a cosmic wall. Since the universe is estimated to be about 13.7 billion years old, the galaxies were born sometime within the first billion years of the cosmos. 

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