A gamma ray burst unleashes so much energy that it is hard to understand. That is a lot of energy. No one knows what causes these explosions, but astronomers have lots of ideas. One idea is that two superdense stars, called neutron stars, crash into each other. All of the mass in the two stars turns into energy in an explosion that we can detect billions of light years away.
Some astronomers disagree with that idea.
They think that gamma-ray bursts are caused by hyperactive supernova explosions. Just last month, in March 2000, scientists noticed a huge gamma-ray burst. Three different satellites registered a 10 second burst of high energy gamma radiation. These satellites were able to pinpoint where the rays came from. Astronomers were then able to look at the right place in the sky and photograph the fireball.