text: The theory of seafloor spreading was connected to changes in this entity by the Vine-Matthews-Morley hypothesis.
full_question: The theory of seafloor spreading was connected to changes in this entity by the Vine-Matthews-Morley hypothesis. Those changes involving this entity were first identified by Motonori Matuyama, and the homing pigeon is thought to get its navigation skills from its ability to sense this thing. This entity was impacted during the Laschamp event. It names a region of the atmosphere in which solar wind particles are deflected. The dynamo theory predicts that this thing is generated by the motion of liquid metals in the core. This thing occasionally undergoes complete reversals. For 10 points, name this field whose non-geographic poles are pointed to by a compass.
first_sentence: The theory of seafloor spreading was connected to changes in this entity by the Vine-Matthews-Morley hypothesis.
raw_answer: Earth's magnetic field [or word forms; accept geomagnetic field; prompt on "magnetic field"; prompt on "magnetosphere"]