Earth & Cosmos / Earth, Climate & Environment

The Earth as a Magnet (Gilbert)

William Gilbert's 'De Magnete' (1600) shows by experiments with a magnetic globe that the Earth itself is a giant magnet.

Gilbert explained why compass needles point north and also dip, and distinguished magnetism from static electricity. Paleomagnetism, the record of the field in rocks, later became key evidence for plate tectonics.