News Astronomy

Ultrahigh energy cosmic rays come from outside the Milky Way

Huge experiment is trying to track the particles back to their sources

Pierre Auger Observatory

LYING IN WAIT  Huge tubs of water (one shown) at the Pierre Auger Observatory in Argentina reveal the tracks left as cosmic particles zip through them.

Steven Saffi

By Lisa Grossman

- More than 2 years ago

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The largest study yet of the most energetic particles to slam into Earth provides the first solid clues to where the particles come from.