An artist's impression of a gamma-ray burst, a powerful jet of energy lasting from less than a second to several minutes. The most powerful events in the universe, they are thought to be mostly associated with the explosion of stars that collapse into black holes. A. Roquette/ESO hide caption

itoggle caption A. Roquette/ESO

A composite of Lyrids over Huntsville, Ala., in 2009. This year, the meteor shower will hit its peak before dawn Sunday morning. Danielle Moser/MSFC/NASA hide caption

itoggle caption Danielle Moser/MSFC/NASA