Cosmologists and physicists have been arguing about (and chasing after) it for years now, but NASA are pretty convinced that they’ve seen dark matter ‘in the wild’. Using Chandra and a group of other telescopes, they observed the collision of two clusters of galaxies, touted as the most energetic cosmic event beyond the Big Bang that we know of. The hot gases in the collision were slowed down by the collision, but other components appeared to not be affected – which is taken to mean that the mysterious dark stuff is there, just as the theories predict.