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Cosmic rays

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Intro to Astronomy

Definition

Cosmic rays are highly energetic particles that originate from outer space and travel at nearly the speed of light. They consist mostly of protons, but also include heavier atomic nuclei and electrons.

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5 Must Know Facts For Your Next Test

  1. Cosmic rays are primarily composed of protons, with a smaller fraction of helium nuclei and other heavy elements.
  2. They originate from supernova explosions, active galactic nuclei, and other high-energy astrophysical events.
  3. Cosmic rays can penetrate Earth's atmosphere and are responsible for creating secondary particles when they collide with atmospheric molecules.
  4. The energy of cosmic rays can range from a few million electron volts (MeV) to over 10^20 electron volts (eV).
  5. Understanding cosmic rays helps astronomers study the processes in massive star evolution and the interstellar medium.

Review Questions

  • What are the primary components of cosmic rays?
  • How do cosmic rays interact with Earth's atmosphere?
  • Why are supernovae significant sources of cosmic rays?
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