heliosphere

noun Astronomy.

1. the region around the sun over which the effect of the solar wind extends.

noun

1. the region around the sun outside of which the sun’s influence is negligible and interstellar space begins

1. The large, roughly elliptical region of space around the Sun through which the solar wind extends and through which the Sun exerts a magnetic influence. The heliosphere extends well beyond the orbits of the planets, and its shape and extent fluctuate with changes to the solar wind and other influences.♦ The boundary between the heliosphere and interstellar space is known as the heliopause.