9212osd (05/05/83)
The April 30, 1983 issue of SCIENCE NEWS has an article titled: "Solar system escape: How far is out?" by J. Eberhart. This is a summary of the article. Four spacecraft are heading out of the solar system, with Pioneer 10 and Voyager 1 ahead of the others. The question of who will reach the edge first depends on how you define the edge. EDGE WINNER Present orbital distance of Pluto from the Sun PIONEER 10 4/25/83 The above for Neptune which is now the outermost planet PIONEER 10 6/13/83 Cross the orbits of all known planets VOYAGER 1 11/88 Pluto's aphelion distance PIONEER 10 6/19/90 Reach the heliopause (1) VOYAGER 1 date not given Oort cloud (2) VOYAGER 1 about 15,000 years from now (1)- as high as 20 billion km, the boundary between the sun's mangetosphere and the interstellar "wind" through which the system is moving. (2)- the source of many long-period comets 6-15 trillion km away