Traditional astronomy makes use of light in the visible part of the electromagnetic spectrum.
Our sun, and most 'normal' stars, emit the majority of their light in these familiar colors of the rainbow. The vast majority of gamma rays which encounter the earth's atmosphere collide with the atmosphere and never reach the surface. The result is that nearly all of gamma-ray astronomy must be performed either at very high altitudes, with aircraft or balloons, or above the atmosphere entirely, aboard satellite observatories. Once thought to be galactic in origin, astronomers now believe the objects that can suddenly emit 1000 times more gamma-ray energy than any other source in the sky and then vanish, lie far beyond our own Milky Way galaxy. Supernovae are also important to gamma-ray astronomy as they often result in the birth of neutron stars, pulsars and black holes.