What is the name of the double star in Ursa Major?

Mizar and Alcor are indeed the well-known double star system located in the constellation Ursa Major. Mizar is the brighter star in the pair and is often noted for being one of the first examples of a double star observed through a telescope. It is visible to the naked eye, while Alcor, the fainter star, is close enough to Mizar that it can be seen without optical aid by many observers.

This double star is significant not just for its visibility but also for its historical context in astronomy, as it has been used as a test of eyesight for centuries. In the context of the options given, the other pairs of stars mentioned do not belong to the Ursa Major constellation. Polaris, also known as the North Star, is located in Ursa Minor, while Thuban is found in Draco. Spica and Antares are part of the constellations Virgo and Scorpius, respectively, and Algol is located in Perseus, while Aldebaran is in Taurus. Therefore, Mizar and Alcor are uniquely positioned in Ursa Major, making this choice the correct answer.