Gamma rays are formed by changes in the atomic nuclei and are also the decay products of collisions between cosmic rays and interstellar matter. Although highly energetic, most gamma rays are absorbed by the earth's atmosphere. Gamma Ray astronomy didn't really begin until the space age provided satellite detecting devices. Through gamma ray astronomy the study of our galaxy has been aided in many ways. We have begun to understand the high energy processes occurring in outer space such as neutron stars, quasars and black holes.
Ultraviolet radiation is another form of radiation used in exploring outer space.
The wavelengths of Ultraviolet radiation range between 4000 angstrom units and 150 angstrom units. Natural ultraviolet radiation is produced mainly by the sun. However ultraviolet radiation can also be produced artificially by electric-arc lamps. Ultraviolet radiation is very useful in astronomy. Ultraviolet radiation detectors have been used since the early 1960's on artificial satellites.