One of astronomy's most baffling mysteries is the undiscovered source of sudden, intense bursts of gamma rays. The Compton Observatory typically detects one burst a day. The bursts differ greatly in duration and appear randomly from any direction. They are not known to repeat.

Amazingly, once a burst fades away, no trace of it remains. No known object has yet been linked with any gamma-ray burst.

A Serendipitous Discovery Gamma-ray bursts were first recorded accidently in 1967 by the Vela satellites. These satellites were developed to look for clandestine nuclear tests by searching for telltale x-rays or gamma rays emitted from nuclear explosions. But the gamma-ray bursts the satellite discovered came from deep space.

Astronomers expected to associate the locations of the bursts with known stars or galaxies. But despite many observations by many different telescopes, no such identification has ever been made.

Enter BATSE The Compton Observatory's Burst and Transient Source Experiment--BATSE--was specifically designed to investigate gamma-ray bursts. The eight large detectors located at the corners of the spacecraft allow BATSE to monitor the entire sky continuously.

Strange Stars or Cosmic Collisions? Many theories have been advanced to explain the distribution and origin of the bursts, but none answers all the questions the bursts pose. Some scientists say the sources of the bursts are relatively close, and others say they are some of the most distant objects in the known universe. Gamma-ray bursts may come from relatively nearby, perhaps from a spherical "cloud" of neutron stars that could surround our own Milky Way galaxy.

(Courtesy of the National Air and Space Museum) Other theories propose that the bursts emanate from the outer reaches of the observable universe, perhaps from violent collisions between neutron stars and black holes.

(Courtesy of R. Windhorst (ASU) and NASA)

See the first-detected gamma-ray burst and the satellite that detected it... See what scientists thought about bursts before the Gamma Ray Observatory... Learn about gamma rays... What in the universe emits gamma rays? Learn about the observatory...

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• Text taken from NASA web page on GRB's