We’re all familiar with the sun’s daily motion in the sky. It rises in the east, gets higher in the sky until circa noon, then begins its hours-long descent to set on the western horizon.

You may also know of our star’s more stately annual journey. For Northern Hemisphere dwellers, as summer approaches, it moves a tiny bit higher in the sky every day at noon until the June solstice, when it turns around and starts to get lower every day until the December solstice.

These motions are the clockwork of the sky. They repeat with enough precision that we base our measurements of passing time on them. But there are more than two gears to this cosmic mechanism; in addition, there are subtle and elegant—though somewhat bizarre—cogs that swing the sun’s position in the sky back and forth during t

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