According to Greek mythology, Callisto, a river goddess, was the daughter of Lycaon, the king of Arcadia. She was one of the favourite companions of the moon goddess Diana (Artemis) and used to accompany her on the hunt. Like all the other nymphs of Diana, she also took a vow to remain a virgin forever. One day Jupiter (Zeus) saw the beautiful Callisto and immediately fell in love with her. He was, in fact, very much attracted by her magnetic beauty and was desperate to have sex with her. In order to get intimate with Callisto in an easier way, Jupiter disguised himself as Diana and lured her into his embrace.
Callisto’s subsequent pregnancy was discovered several months later, while she was taking a bath with Diana and her fellow nymphs. Diana became so much agitated, upset and enraged, that she immediately expelled Callisto from her group. With time, Callisto gave birth to a male child named Arcas.
The story did not end there. When Juno, the wife of Jupiter, found out the truth, she became mad at Callisto and to avenge her wounded pride, she transformed Callisto into a huge bear. Callisto was, naturally very much unnerved by her physical transformation and ran away in shame from the locality to hide in seclusion. She ran deep into the woods for self protection.
Sixteen years later, when Arcas was grown up to be a handsome young man, he once decided to go out for hunting, and without knowing anything about the past, went into the same woods where his mother Callisto lived. When he was deep in the woods, suddenly Callisto saw him and within no time, recognized Arcas. On seeing her own child after so many years, she was so much overwhelmed with emotion that Callisto forgot about her physical transformation and her present look. She rushed towards Arcas with open arms to embrace him. However, Arcas was scared at the sight of a rushing bear and to protect himself from the possible attack, he lifted his bow and shot at the charging bear, who was none but his poor unfortunate mother.
However, at the eleventh hour, just before it was too late and just before the arrow struck poor Callisto, Jupiter tossed Callisto and her son Arcas into the heavens, and they became the constellations ‘Ursa Major’ and ‘Ursa Minor’, the big and little bears. Today, these constellations are also known as the Big Dipper and the Little Dipper.