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The Question

(Submitted January 06, 1999)

Why do we study cosmic rays? I understand that they might come form exploding stars, but why do we study them and for what purpose would it serve?

The Answer

We study cosmic rays because they are one of our few samples of matter from outside the solar system. Studying the composition of cosmic rays tells us how the galaxy has continued to evolve chemically since the solar system was formed. This helps us to understand how the solar system got the chemical composition that it has, and so tells us about our origin. Studying how cosmic rays have gotten to us tells us about the dynamics of the Milky Way galaxy. Also, historically, many new particles (muons and pions for example) were discovered first in the cosmic rays.

For more information on cosmic rays, you can check the Cosmicopia at:

Thanks for your questions

Eric Christian
for Ask an Astrophysicist

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