Cosmic Ray Counts on the Rise for Voyager 1

This graphs shows the amount of cosmic rays encountered by the Voyager 1 spacecraft from June 2011 to June 2012 with an increase starting in May 2012.

From January 2009 to January 2012, there had been a gradual increase of about 25 percent in the amount of galactic cosmic rays Voyager was encountering. Beginning on May 7, 2012, the cosmic ray hits have increased five percent in a week and nine percent in a month. This sharp increase in cosmic rays could herald Voyager 1's long-awaited breakthrough to interstellar space. Credit: NASA/JPL

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