As you read this, it’s only two short days to Christmas and nine to New Year’s Day, but the length of our winter days is subtly increasing. Two days ago, at the winter solstice, Earth’s star began its slow upward arc towards summer 2022. Last Saturday an impressive full moon rose and set close to the sun’s June 21 position, high to the northeast and northwest.

Thanks to the Earth’s elliptical orbit, Dec. 7 was the earliest sunset of the year; two weeks from now, Jan. 7 will host the lat...