A Portrait of the Dumbass as an Old Man

Way Cool Picture

Quick hitter, here is a great picture from NASA's "Astronomy Picture of the Day", the most excellent site that my most excellent baby sister pointed me at, that I check daily. This shows the aftermath of one cluster of galaxies, the smaller one on the right, punching through the center of the larger cluster on the left. The magenta is X-ray imaging from the Chandra X-ray telescope -- clusters of galaxies are the primary extragalactic objects you see in X-ray. The cone on the right is the shock wave of the smaller cluster's passage -- unbelievable, a sonic boom in intracluster gas.

The blue is artificial, the cluster "dark matter" as inferred from gravitational lensing of background galaxies. This has gotten a fair amount of press as the first proof of the existence of dark matter, and shows that it is weakly bound by gravity, as it is not being affected like the gas (magenta) is.

There are cool animations of the collision here.