Boundary between the heliosphere
the teardrop-shaped region around the Sun created by the solar wind and filled with solar magnetic fields and outward-moving gas
and the zone of transition to the interstellar medium .
Its tail is estimated to reach 50–100 astronomical unit s from the Sun, encompassing the orbits of all the major planets. Its shape changes, influenced by a wind of interstellar gas produced by the Sun's motion through it.