A bow shock is the area between a magnetosphere and an ambient medium. For stars, this is typically the boundary between their stellar wind and the interstellar medium.
In a planetary magnetosphere, the bow shock is the boundary at which the speed of the solar wind abruptly drops as a result of its approach to the magnetopause. The best-studied example of a bow shock is that occurring where the solar wind encounters the Earth's magnetopause, although bow shocks occur around all magnetized planets. The Earth's bow shock is about 17.3 km thick and located about 90,000 km (56,000 mi) from the Earth.
For several decades, the solar wind from the Sun was thought to form a bow shock when it collides with the surrounding interstellar medium. This long-held belief was called into question in 2012 when data from the Interstellar Boundary Explorer (IBEX) found the solar system to be moving slower through the interstellar medium than previous believed. This new finding suggests that beyond the termination shock and heliopause surrounding the solar system there is in fact no bow shock.
Read more about Bow Shock: Description, Bow Shock Theory For Earth's Sun, Bow Shock in The Infrared
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