A gamma-ray burst

This artist's impression illustrates how a gamma-ray burst can flare dramatically over a short time period (gamma ray bursts usually last between a hundredth of a second to a hundred seconds). The bursts can occur as often as several times a day. There is no way to predict when or where they will next occur.

ESA missions such as XMM-Newton, Integral and Ulysses study these mysterious, powerful bursts.