Background Radiation
Astrophysics
Filling all space, e.g. the radiation from the early, hot universe.
- — The Universe Adventure Glossary retrieved 2014-05-20
Nuclear Physics
The radiation of man's natural environment originating primarily from the naturally radioactive elements of the earth and from the cosmic rays. The term may also mean radiation extraneous to an experiment.
- — Glossary of Nuclear Science Terms retrieved 2014-05-20