coined 1959, from magneto- + sphere. So called because it is the region around the earth (and some other planets) in which the magnetic field of the planet plays a dominant role in the motion of particles.
early 15c., "a delay, a temporary rest in singing or speaking," from Old French pausee "a pause, interruption" (14c.) and directly from Latin pausa "a halt, stop, cessation," from Greek pausis "stopping, ceasing," from pauein "to stop (trans.), hold back, arrest, to cause to cease," a word of uncertain etymology with no certain cognates outside Greek [Beekes]. Later also "a hesitation proceeding from doubt or uncertainty;" hence to give (one) pause "cause to stop or hesitate" (c. 1600).