heliopause hurmarz Fr.: héliopause The edge of the solar system where the pressure of the → solar wind balances that of the → interstellar medium plasma. In other words, the surface boundary that separates the → heliosphere from interstellar space. It is estimated to be situated 100 → astronomical units or more from the Sun. A → bow shock likely forms as the interstellar medium wind approaches the heliosphere and is deflected around the heliosphere, forcing it into a teardrop-shaped structure with a long, comet-like tail. From → helio- + pause "break, cessation, stop," from M.Fr. pause, from L. pausa "a halt, stop, cessation," from Gk. pausis "stopping, ceasing," from pauein "to stop, to cause to cease." Hurmarz, from hur, → helio-, + marz "frontier, border, boundary," → frontier. |