Castor and Pollux meet the moon, March 10 to 12

Castor and Pollux, fattened half circle with two dots on the left, and constellation below. — The waxing gibbous moon approaches Castor and Pollux March 10 to 12, 2022. Chart via John Jardine Goss.

On March 10, 2022, you can see the 1st-quarter moon among the stars we in the Northern Hemisphere associate with the winter season. The moon floats above the upraised club of Orion the Hunter. On March 10, the moon is still some distance from Castor and Pollux in the constellation Gemini the Twins. If you watch over March 10 to 12, you’ll see the moon slide toward these stars, moving closer to them on each consecutive night.

On March 11, the moon hops from Taurus into Gemini. Notice that it has moved toward the east (toward the sunrise direction) relative to Castor and Pollux. That day-by-day eastward motion on our sky’s dome is a reflection of the moon’s motion in orbit: always toward the east; however, during the course of a night, the moon along with the stars and planets moves toward the west. Also notice that the moon is growing fatter. Full moon will come on the night of March 17-18 for us in the Americas (7:18 UTC on March 18).

On March 12, a 74%-lit moon pairs closely with Castor and Pollux. On this date, the moon is closer to Pollux than Castor. Notice that Pollux is the brighter of the two stars, and also notice how bright and close together Castor and Pollux are on our sky’s dome. If you keep watching after March 12, and wait for the moon to move away, you’ll be able to find Castor and Pollux again and again. You’ll be able to notice that Pollux is golden in color, while Castor is white.