• July 20, 2006

    Episode 47: A Distant Cluster of Galxies

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    Astronomers combing through the archives of x-ray observations taken by the XMM-Newton telescope have found the most distant cluster of galaxies ever seen. The objects, embedded in hot gas that glows with x-rays, are located nearly 10 billion light years away. They offer a tantalizing glimpse of what galaxy clusters would have been like at the earliest stages of their formation. Strangely, though the cluster — named XMM 2215-1738 — must have formed when the universe was relatively young, its galaxies' colors indicate old age.