An asymmetric region surrounding a planet, star, or other body, in which the body's magnetic field traps charged particles and dominates their behavior.
That region surrounding a planet in which the planet's magnetic field is stronger than the interplanetary field: the solar wind gives it a cometlike shape with the tail extending from the night side of the planet for vast distances.
A highly asymmetrical region surrounding the Earth, beginning about 100 km (62 mi) above the surface on the side of the Earth facing the Sun and extending hundreds of thousands of kilometers into space on the opposite side. In this region the Earth's magnetic field exerts a significant influence on any charged particles that encounter it. The magnetosphere deflects most of the charged particles in the solar wind , but also traps and deflects some of these particles toward the Earth's magnetic poles, causing magnetic storms and auroras .
Origin of magnetosphere
magneto- +"Ž -sphere