Movatterモバイル変換

Explanation: Where does the Sun's influence end? Nobody is sure. Out past the orbits ofNeptune andPluto extends a region named theheliosphere where theSun's magnetic field and particles from theSolar Wind continue to dominate. The surface where theSolar Wind drops belowsound speed is called thetermination shock and is depicted as the inner oval in theabove computer-generated illustration. It is thought that this surface occurs as close as 75-90AU -- so close that aPioneer orVoyager spacecraft maysoon glide through it as they exit theSolar System at about 3 AU/year. The actual contact sheet between the Sun'sions and the Galaxy's ions is called theheliopause and is thought to occur at about 110 AU. It is depicted above as the middle surface. The Sun'sheliopause moves through thelocal interstellar medium much as a boat moves on water, pushing abow shock out in front, thought to occur near 230 AU.