heliosphere

noun

Etymology: Etymology tree Proto-Indo-European *sóh₂wl̥ Proto-Indo-European *sh₂wél(i)yos Proto-Hellenic *hāwélios Ancient Greek ἥλῐος (hḗlĭos) English helio- Ancient Greek σφαῖρᾰ (sphaîră)bor. Latin sphaera Late Latin sphērader. Old French spherebor. Middle English spere English sphere English -sphere English heliosphere From helio- + -sphere.

1. The region of space where interstellar medium is blown away by solar wind; the boundary, heliopause, is often considered the edge of the Solar System.

   “The heliosphere isn’t really a sphere at all, more an elongated teardrop shape.”