WHAT ARE COSMIC RAYS ?
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This photo of the remains of Supernova 1987A
was taken by Hubble Space Telescope 7 years
after the star exploded.
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Cosmic rays are high energy particles
from outer space.
About 1000 cosmic rays per second strike
each square meter area of Earth's atmosphere.
Cosmic rays are produced in our Galaxy
by supernova explosions and by objects such as neutron stars and
black holes. Cosmic rays are also produced by the Sun during
violent events called coronal mass ejections.
About 90 % of Galactic cosmic rays are protons,
9 % are helium nuclei, and the rest are nuclei of heavier atoms.
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