Dark Matter observed by KIPAC/SLAC (CA) in a galaxy cluster 3 billion light years from earth using gravitational lensing to detect DM mass (DM doesn't reflect light or give off heat but GL detects the distortion in light of background galaxies caused by DM), artificial colour applied to distinguish between dark matter (blue) and luminous matter (red). The bullet cluster consists of 2 clusters of galaxies passing through one another. As the two clusters cross at a speed of 10 million miles per hour, the luminous matter in each cluster interacts with the luminous matter in the other cluster and slows down. But the dark matter in each cluster does not interact at all, passing right through without disruption. This difference in interaction causes the dark matter to sail ahead of the luminous matter, separating each cluster into two components: dark matter in the lead and luminous matter lagging behind. Observations were made using the Hubble Space Telescope, the Magellan Telescope.