Separation Anxiety: Cosmic collision may shed light on dark matter

12:37pm, August 22, 2007

Some 3 billion years ago, two massive clusters of galaxies collided head on. The debris from this ancient cosmic train wreck, astronomers say, might pose a new puzzle about the invisible material believed to account for most of the mass in the universe.

A variety of evidence indicates that this material, known as dark matter, is about eight times as abundant as ordinary matter and that it resides in vast, invisible halos around star-filled galaxies. Dark matter keeps galaxies and galaxy clusters intact, theorists say.

This article is available only to subscribing members. Join SSP today or Log in.

More from Science News