Cosmic Rays Tracked (broadcast Friday, November 9th, 2007)

A cosmic ray event viewed by all four fluorescence detectors at the Pierre Auger Observatory. Each detector records the growth and decay of the extensive cosmic ray air shower comprised of billions of secondary particles. Pierre Auger Observatory

For years, astronomers have been trying to locate the source of high-energy cosmic rays that hit the Earth's atmosphere. In new work published this week in the journal Science, researchers report that the most energetic cosmic rays they detected can usually be traced back to areas of the sky that contain nearby Active Galactic Nuclei, which are thought to be powered by supermassive black holes devouring large amounts of matter. The work was based on detailed observation of 77 extremely high energy cosmic ray events using the Pierre Auger Observatory in Argentina. In this segment, Ira and guests talk about the findings and what they might mean. Teachers, find more information about using Science Friday as a classroom resource in the Kids' Connection.