Cosmic rays

Particles that bombard the Earth from anywhere beyond its atmosphere are known as cosmic rays. Cosmic rays don't take pretty pictures, but studying the quantity and type of these particles helps us to understand the acceleration processes involved and to measure the composition of the Sun, as well as sources at the far distant reaches of the galaxy.

Cosmic rays include:

   * Galactic Cosmic Rays -- coming from outside the solar system
   * Anomalous Cosmic Rays -- coming from the interstellar space at the edge of the heliopause
   * Solar Energetic Particles -- associated with solar flares and other energetic solar events

   * The term "cosmic rays" used to include X-rays and gamma rays, which are well covered in Imagine the Universe!