image: A water-Cherenkov detector seen against the night sky at the Pierre Auger Observatory in western Argentina. This material relates to a paper that appeared in the Sept. 22, 2017, issue of Science, published by AAAS. The paper, by The Pierre Auger Collaboration, and colleagues was titled, "Observation of a large-scale anisotropy in the arrival directions of cosmic rays above 8 × 1018 eV." view more
Credit: Steven Saff