Happy (Belated) Winter Solstice!

The day the sun stands still, as the etymology says.

Some ancients thought — sensibly enough in context of the knowledge and methods humans had developed at that point — that the sun went around the earth.

Getting more advanced, to explain why the sun was higher in the sky at some times during the year (about 87º at noon in June in Houston TX) and lower in the sky at other times (about 37º at noon in December in Houston TX), they thought the sun was orbiting the earth (whether flat or round) in a spiral. Think of it as the sun traveling up and down a cylinder that encircles the earth.

At our Northern Hemisphere summer solstice, the sun would be higher up the cylinder, at the top, turning around to start cycling back down. At the Northern Hemisphere winter solstice, the sun would be lower down on the cylinder, at the bottom, turning around to go back up.

Here is a diagram from p. 43 of Elements of Astronomy by Simon Newcomb.

See also “Understanding Astronomy The Sun and the Seasons.”