Scientists home in on the make-up of cosmic rays, which are more nuanced than previously thought.
By Leah Hesla
Unlike the twinkling little star of nursery rhyme, the cosmic ray is not the subject of any well-known song about an astronomical wonder. And yet while we know all about the make-up of stars, after decades of study scientists still wonder what cosmic rays are.
Thanks to an abundance of data collected over eight years, researchers in the Pierre Auger collaboration are closer to finding out what cosmic rays—in particular ultrahigh-energy cosmic rays—are made of. Their composition would tell us more about where they come from: perhaps a black hole, a cosmic explosion or colliding galaxies.