Voyager 1 Treks Past Solar System to Unexpected Frontier

After 36 years and a journey that took the spacecraft 12 billion miles beyond the sun, Voyager 1 has left the solar system, the first human jaunt into interstellar space, U.S. scientists said.

The probe crossed into a region of cold, dark space outside the heliosphere, a bubble of charged particles at the boundary of the solar system, on Aug. 25, 2012, according to a report in the journal Science by researchers from the National Aeronautics and Space Administration and the University of Iowa.