1. Gilbert sketch Gilbert's sketch of the alignment of bar magnets at various latitudes on the earth, from his book De Magnete, as reproduced at www.gutenberg.org/ebooks/3 3810. The earth's rotation axis is horizontal in this diagram. At the poles, the magnets point directly along the vertical direction. www.gutenberg.org/ebooks/3 3810

2. Magnetic pole history History of the north magnetic pole location as provided by Tentotwo at Wikimedia Commons. TentotwoWikimedia Commons

3. Magnetic reversals History of magnetic field reversals, as determined from geologic records. Dark regions indicate times when the magnetic field had the same orientation as today; light areas indicate times when the magnetic field was reversed. Image available from The U.S. Geologic Survey via Wikimedia Commons. Wikimedia Commons