Voyager 2 Reaches The Heliosphere

Like its sister craft, Voyager 1 several years ago, Voyager 2 has now flown far enough out into the solar system to encounter the heliosphere, where the wind of solar particles meets the interstellar medium. We already know that the surface of this boundary zone is irregular in shape because of earlier measurements by Voyager 1 (http://www.aip.org/pnu/2006/split/778-1.html).

Voyager 1 is currently about 9.8 billion miles from Earth and traveling out at a speed of 38,000 miles per hour. Voyager 2 is about 7.8 billion miles away and traveling at about 35,000 miles per hour. Voyager 1 might be faster, further, and earlier, but Voyager 2's plasma measuring instrument is functioning, unlike Voyager 1's. Voyager 2 confirms that the boundary layer is irregular and has found that the temperature just beyond the boundary is some ten times cooler than expected. (Results reported at this week’s meeting of the American Geophysical Union in San Francisco.)