I Zwicky 18
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I Zwicky 18 is a galaxy 45 million light years away. It is named after Swiss astronomer Fritz Zwicky, who first photographed it in the 1930s.
I Zwicky 18 is 500 million years old, which makes it practically an infant (by comparison, most galaxies, including our own Milky Way, are approximately 12,000 million years old). It may still be creating Population III stars - spectroscopy shows that its stars are composed almost entirely of hydrogen and helium, with heavier elements almost completely absent. It is thought that either the galaxy formed really recently, as its "normal" matter appears to indicate, or it has been around for thousands of millions of years as a dark galaxy, and has only recently picked up the required mass in hydrogen and helium, which other galaxies have done thousands of millions of years ago.
External links
- [Hubble Uncovers a Baby Galaxy in a Grown-Up Universe]
- http://www.newscientist.com/article.ns?id=dn7056
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