Colliding Galaxies--August 8, 2007
Three galaxies the size of our own Milky Way and a fourth that’s even bigger are smashing into each other in an unprecedented galactic pileup. That’s the finding of a NASA telescopic survey of a cluster of galaxies about 5 billion light years from us. The report will appear in Astrophysical Journal Letters.
Galaxies are known to merge. The Milky Way and the Andromeda galaxy are on a collision course that will lead to a combined galaxy in some 5 billion years. But this four galaxy merger is the first known case of more than two large galaxies coming together.
Kenneth Ries of the Harvard-Smithsonian Center for Astrophysics said "Most of the galaxy mergers we already knew about are like compact cars crashing together. What we have HERE is like four sand trucks smashing together, flinging sand everywhere." The grains of sand are stars.
Once the merger is complete the new galaxy will be one of the biggest known, up to 10 times the size of the Milky Way.