Binary White Dwarf
Two white dwarfs have been discovered on the brink of a merger. In just 900,000 years, material will start to stream from one star to the other, beginning the process that may end with a spectacular supernova explosion. Watching these stars fall in will allow astronomers to test Einstein's theory of general relativity as well as the origin of a special class of supernovae. Credit: David A. Aguilar (CfA)