Gemini (astronomy) (Latin for “twins”), a zodiacal constellation, that is, a constellation located along the ecliptic, the apparent annual path of the sun across the sky (see Zodiac). Gemini is visible in the Northern Hemisphere. Its most prominent features are two bright stars, Castor and Pollux; it also includes a star cluster visible to the naked eye on clear, moonless nights. The astronomers of ancient Egypt symbolized this constellation by a pair of young goats; the Arabians by peacocks; and the Greeks by twin children.