News from the Edge of Interstellar Space

Abstract

Auroral activity and magnetic storms that occasionally disrupt electric power grids are caused by the supersonic solar wind that sweeps past Earth as it blows radially away from the Sun. This wind creates the heliosphere, a bubble of magnetized plasma that surrounds the Sun and includes the orbits of all known planets. Two spacecraft, Voyager 1 and 2, are approaching the edge of the heliosphere the heliopause where the radially decreasing pressure of the expanding solar wind balances the inward pressure of the local interstellar medium. En route, the spacecraft are sending back important information about the far reaches of the solar system.