Portal:Astronomy/Picture/13 August 2005

This optical afterglow of gamma-ray burst GRB 990123 was taken in 1999 by the NASA Hubble Space Telescope. Gamma-ray bursts (GRBs) are the most luminous physical phenomena that can currently be seen from Earth. They emmit gamma rays for a short period of time (anywhere from seconds to hours), then X-rays for several days afterwards. Though their cause is unknown, it is widely specualted that they arise from a hypernova, where a large star collapses into a black hole, and large amounts of energy and matter are exerted.