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 (as shown in this artist's conception), beginning the process that may end with a spectacular supernova explosion. Watching these stars fall in will allow astronomers to test Einstein's general theory of relativity as well as the origin of a special class of supernovae. David A. Aguilar (CfA)