Edge of the Solar System

Edge of the Solar System

. Voyager 1 and 2 spacecraft, located at a distance of about 90 AU and 70 AU, approach the place where the Solar System ends and interstellar space begins. One AU is the mean distance between the Earth and the Sun, and the edge of the Solar System is located at roughly 100 times this distance. At the termination shock, the supersonic solar wind abruptly slows from an average speed of 400 kilometers per second to less than one quarter that speed. Beyond the termination shock is the heliosheath, a vast region where the turbulent and hot solar wind is compressed as it presses outward against the interstellar wind. The edge of the Solar System is found at the heliopause, where the pressure of the solar wind balances that of the interstellar medium. A bow shock likely forms as the interstellar wind approaches and is deflected around the heliosphere, forcing it into a teardrop-shaped structure with a long, comet-like tail. (Courtesy of JPL and NASA.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University