Highest-energy cosmic rays have extragalactic origin

(CNRS) A 50-year-old debate has at last been settled: the highest-energy cosmic rays do not originate in our own Galaxy but in galaxies located tens or even hundreds of millions of light years away. The evidence comes from the Pierre Auger Observatory in Argentina, which has been gathering data since 2004 about these particles that constantly bombard the Earth. The CNRS is the observatory's principal French funding agency.