Starwatch: a close lunar encounter with Pollux

The brightest star in the constellation Gemini, the twins, is named after the son of Leda and Zeus

On the evening of 23 November, the moon will have a close encounter with the star Pollux, the brightest star in the constellation Gemini, the twins.

Pollux marks the head of one twin. The other twin is marked by the star Castor. Although Pollux is the brighter star, it was Castor that was given the designation alpha Geminorum by German astronomer Johann Bayer in his 1603 star atlas Uranometria, which was the first to chart the entire celestial globe. Although Bayer mostly designated stars in brightness order, by giving Pollux the beta Geminorum designation we can see that this was not a hard and fast rule.