Which constellation contains the stars Mizar and Alcor?

The stars Mizar and Alcor are located within the constellation Ursa Major. Mizar is notably part of the "Big Dipper," which is an asterism often associated with this constellation. Specifically, Mizar is the middle star of the handle of the Big Dipper and is famous for being a double star, with Alcor as its companion. Observers can spot Mizar and Alcor relatively easily; Alcor, being dimmer, is sometimes referred to as the "horse and rider" in historical astronomical observations, where Mizar represents the rider and Alcor the horse.

Ursa Major, which translates to "Great Bear," is one of the most recognizable constellations in the northern sky, containing several other bright stars beyond just Mizar and Alcor. In contrast, the other constellations mentioned do not contain these stars; Ursa Minor, while also part of related mythologies involving bears, features different stars, primarily Polaris. Bootes, known for the bright star Arcturus, and Cassiopeia, famous for its distinctive W shape, belong to entirely different regions of the sky, making them unrelated to Mizar and Alcor. Thus, Ursa Major is the correct answer as it directly encompasses