Cosmic ray

Cosmic rays are high-energy protons and atomic nuclei which move through space at nearly the speed of light. They originate from the sun, from outside of the solar system in our own galaxy, and from distant galaxies. Upon impact with the Earth's atmosphere, cosmic rays can produce showers of secondary particles that sometimes reach the surface.

Origin

Cosmic rays are understood to be generated by a variety of processes, including supernova explosions within our galaxy, and also during the formation of stars. They can also be produced by phenomena such as gamma-ray bursts and active galactic nuclei outside our galaxy.

Composition

Cosmic rays are composed primarily of protons and alpha particles, but also include other nuclei such as lithium, beryllium, and boron. A small fraction are stable particles of antimatter, such as positrons or antiprotons. The precise nature of this remaining fraction is an area of active research.

Detection

Cosmic rays can be detected in a variety of ways, including through the use of cloud chambers, bubble chambers, and emulsion plates. More recently, large-scale detectors such as the Pierre Auger Observatory and the IceCube Neutrino Observatory have been constructed to study cosmic rays.

Health effects

Cosmic rays can have a variety of health effects on humans, particularly for those in high-altitude environments or in space. These effects can include cancer, cataracts, and cardiovascular disease. Measures are taken to protect astronauts from the health effects of cosmic rays, including the use of shielding and the monitoring of individual exposure.

See also

• Solar particle event
• Van Allen radiation belt
• Cosmic ray visual phenomena
• Cosmic Ray Air Shower

References

Cosmic ray Resources
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