Which constellation are the stars Castor and Pollux in?

Castor and Pollux are in the constellation Gemini.

Gemini is one of the 12 zodiac constellations and its name is Latin for “twins.” Castor and Pollux appear as the heads of the two figures traditionally drawn in the constellation, making them among the easiest stars to use when identifying Gemini in the night sky. Pollux is the brighter of the pair, while Castor is slightly dimmer.

The stars are linked to the Greek myth of the Dioscuri, twin half-brothers. Castor was mortal, while Pollux was the divine son of Zeus. After Castor died, Pollux asked Zeus to let them remain together, and the brothers were placed among the stars. The myth explains why Gemini is represented by twins, although the stars themselves are not a physically bound pair.

Gemini lies near familiar constellations including Orion and Taurus and is especially prominent in Northern Hemisphere winter skies. Another common mix-up is confusing Gemini with neighboring Auriga; locating Castor and Pollux above Orion is a useful way to distinguish it.