"Zombie" stars that explode like bombs as they die, only to revive by sucking matter out of other stars. According to an astrophysicist at UC Santa Barbara, this isn't the plot for the latest 3D blockbuster movie. Instead, it's something that happens every day in the universe -- something that can be used to measure dark energy.
This is a Chandra X-ray image of Tycho's supernova remnant. This Type Ia sueprnova was observed by Tycho Brahe in 1572, and today is just an expanding ball of gas. Astronomers used to have to wait years for a close, bright supernova to learn about them. Today big surveys are discovering supernovae by the thousands. (Credit: NASA/Chandra X-ray Observatory)