Science glossary film: Cosmic rays

Highly charged particles, originating from outer space. The term comes from the early days of radiation research, when any directed stream of ionising radiation was termed a ray. Cosmic ray particles, as they are now known, are understood to arrive individually, not in the form of a beam. A single particle will release a secondary shower of particles when they hit our atmosphere. Most are simply protons and electrons.

The term comes from the early days of radiation research, when any directed stream of ionising radiation was termed a ray. Cosmic ray particles, as they are now known, are understood to arrive individually, not in the form of a beam. A single particle will release a secondary shower of particles when they hit our atmosphere. Most are simply protons and electrons.