Telescopes from the Ground Up

A strange telescope detects elusive gamma rays

Get to the root of it

Gamma rays come from some of the most mysterious and powerful objects in the universe: black holes, quasars, supernovae, and neutron stars. They speed across the universe, past galaxies, racing between the stars … until they reach the earth, where the atmosphere stops them like a brick wall.

It’s a good thing it does — gamma radiation is highly dangerous to living things. It breaks up molecules and causes mutations. On the unfortunate side, astronomers on Earth can’t see or detect gamma radiation.

Now for something completely different

So in 1991, NASA launched the Compton Gamma Ray Observatory, CGRO. The observatory, named after the astronomer Arthur Holly Compton, spent 9 years orbiting the Earth.

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Space Telescopes
Illustration of the Copton Gamma Ray Observatory in orbit around Earth.
Artist illustration of the Compton Gamma Ray Observatory in orbit.Enlarge picture
Compton Gamma Ray Observatory (CGRO)
Year launched: 1991
Telescope type: Detector
Light collector: Gamma ray counter
Light observed: Gamma ray
Discovery Highlights:
  • Established that all the mysterious sources of gamma-ray bursts lie outside the Milky Way Galaxy. Also, discovered a nearby supernova remnant.