magˈnēd.ə, -ed.əˌˌ noun
Etymology: magnet- + sphere
: a region of space that surrounds a celestial object (as the earth or a star) and is dominated by the object's magnetic field so that charged particles are trapped in it
• mag·ne·to·spheric ̷ ̷ ¦ ̷ ̷ ̷ ̷ ˌ adjective