Cosmic crash unmasks dark matter

[Rick]

Striking evidence has been found for the enigmatic "stuff" called dark matter which makes up 23% of the Universe, yet is invisible to our eyes.

The results come from astronomical observations of a titanic collision between two clusters of galaxies 5.7 billion light-years away.

More: http://news.bbc.co.uk/2/hi/science/nature/7587090.stm