This was one of my more satisfying essays. Several years ago I gave some thought to what it meant for the earth to be considered a magnet. More recently in 2012 an article in the magazine BirdWatching brought it all back when I saw its diagram of the earth as a magnet for guiding migratory birds. Knowing that magnets have north and south poles, where should we expect to find the earth’s north and south magnetic poles? See Earth as Magnet.
Update (2/28/2025) Even Experts Slip Up
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As my opening post, I begin with something I noticed back in 2011 when we purchased a new microwave that had a revolving carousel to distribute the heating. The glass plate was turning faster than the plastic support ring under it. I wondered if the speed depended on the size of the support ring and/or the size of its roller wheels.