Has Voyager 1 left the Solar System? Is it officially the first spacecraft to reach interstellar space? It depends on whom you ask. NASA says no, but W.R. Webber of the New Mexico State University Department of Astronomy and F.B. McDonald of the University of Maryland Institute of Physical Science and Technology say yes. They contend that the unmanned, nuclear-powered probe left the Solar System on August 25, 2012 at a distance of 121.7 AU (18.2 billion km) from the Sun when its instruments on board detected a major shift in cosmic ray intensity.
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