1983 – NASA’s Pioneer 10 flies beyond the orbit of Pluto after completing the first mission to Jupiter. Despite flying beyond Pluto’s orbital path, Pioneer 10 still had not left the solar system, since Pluto’s irregular orbit meant that it was closer to the Sun than Neptune at that point. But on June 13, 1983, Pioneer 10 passed the orbit of Neptune and officially became the first man-made object to leave our solar system. By September 9, 2012, Pioneer 10 was predicted to be about 10 billion miles from the Sun, traveling at about 26,930 mph and heading for the constellation Taurus. At that distance, light from our sun takes almost 15 hours to reach the probe. Its trajectory will take it in the general direction of the star Aldebaran, about 68 light years away. If Aldebaran had a zero relative velocity, Pioneer 10 would still take more than 2 million years to reach it.
April 25, On this Day in Aviation History
