heliosphere

The heliosphere is the region of space including the Sun's magnetic field and the solar wind, charged particles from the Sun. It extends at least 100 AU from the Sun, easily including all the solar system planets. Essentially, you are out of the heliosphere when instead of a wind from the Sun, you are experiencing the wind of the surrounding interstellar medium (ISM). The heliosheath is the portion of the heliosphere where the ISM starts significantly affecting it and the heliopause is the outermost edge.

A generalization of this term applicable to analogous regions around other stars is astrosphere (or occasionally asterosphere).