Hubble Finds Dark Matter

Astronomers have discovered a ring of dark matter in a galaxy cluster about 5 billion light years away. The Hubble Telescope turned up an anomaly in the way stars in the area appear, which researchers think is a distortion caused by the intense gravity of the galactic "glue" holding the cluster together.

Scientists have long guessed that a super-dense, invisible substance creates most of the gravity in the universe, and this discovery could be major progress toward confirming that theory. "Nature is doing an experiment for us that we can't do in the lab, and it agrees with our theoretical models," said one astronomer. (More Hubble stories.)