Longest Galactic 'Tail' Found Near Doomed Galaxy Group.

Astronomers have discovered the longest galactic tail ever seen, measuring over a million light-years long, using data from NASA's Chandra X-ray Observatory and the Sloan Digital Sky Survey. The tail was created by a galaxy group called NGC 4839 as it moved through the Coma Cluster, leaving a trail of hot gas in its wake. The discovery provides a rare opportunity to study the mechanics of how galaxy clusters merge and will eventually disperse as the gas mixes with cooler gases in the cluster.