Cosmic rays maintain their mystery

Excerpt from the November 27, 1965 issue of Science News Letter

illustration of cosmic rays showering Earth

SUBATOMIC SHOWERS  Earth is perpetually pelted by cosmic rays, which trigger cascading showers of subatomic particles (illustrated) when they hit the atmosphere. 

NASA, S. Swordy/University of Chicago

Major energy cosmic? — Previous ideas on how long and how far [cosmic rays] travel in interstellar space were probably incorrect. It now appears that either these nuclei are younger and have passed through less of the Milky Way galaxy than previously thought … or … cosmic radiation fills all of space, not just our galaxy. If this is so, then the physical processes of producing cosmic rays must be as common as those which produce star light. — Science News Letter, November 27, 1965 


The galaxy is teeming with cosmic rays — and we now know a lot more about these subatomic particles that tear through space with tremendous energy, up to roughly 100 billion billion electron volts. The lowest-energy cosmic rays come from the sun. Zippier particles are probably shot out of super­novas within the Milky Way. The source of the most energetic (and rare) cosmic rays are an enduring mystery, but they probably originate from outside our galaxy.

headshot of Associate News Editor Christopher Crockett

Christopher Crockett is an Associate News Editor. He was formerly the astronomy writer from 2014 to 2017, and he has a Ph.D. in astronomy from the University of California, Los Angeles.

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