In Greek mythology, Arcas was the son of Zeus and the nymph Callisto, whom Hera turned into a bear. Arcas unknowningly attempted to kill his mother during a hunt, not recognizing her. Zeus put them both in the sky as Ursa Major (Callisto) and Ursa Minor (Arcas).
According to varying versions, Arcas was raised by Maia or Lycaon.
An alternate version: One of Artemis' companions, Callisto lost her virginity to Zeus, who had come disguised as Artemis. Enraged, Artemis changed her into a bear. Callisto's son, Arcas, nearly killed his mother while hunting, but Zeus or Artemis stopped him and placed them both in the sky as Ursa Major and Ursa Minor.
Hera was not please with the placement of Callisto and Arcas in the sky, so she asked her nurse, Tethys, to help. Tethys, a marine goddess, cursed the constellations to forever circle the sky and never drop below the horizon, hence explaining why they are circumpolar.
