Why are there Ursa Major and Ursa Minor in the Milky Way?

In ancient Greek mythology, there was a beautiful and kind girl named Crystal. She always wears hunting clothes, carries a bow on her shoulder and holds golden hair, and bravely follows Artemis to chase wild animals in the deep mountains and forests. One day, Zeus fell in love with the beautiful Crystal, and he became Artemis to cheat her. Poor callisto couldn't escape Zeus. Zeus proudly returned to the Heavenly Palace. Unfortunately, only innocent callisto found out that she was pregnant. Artemis was so angry that she was driven out of the hunting ground. Helpless callisto built a thatched shed deep in the forest and settled down. Soon after, she gave birth to a boy named Achatz. Hera, Zeus' wife, heard about it. She secretly cast a spell to turn the angelic Callisto into a big bear. Time flies, fifteen years have passed. Little Achatz grew up to be a beautiful young man. Like his mother, he became an excellent hunter. Hera saw that the son of her enemy was so handsome, and the evil spirit of more than ten years ago could not help but come to her mind, and a deadly trap was born in her heart. One day, Achatz was looking for prey in the forest with a pike in his hand. Suddenly, a big bear came slowly towards him. God, how could Achatz think that this bear in front of him is his mother who has been lost for fifteen years! Seeing such a big bear coming at him, he flashed back excitedly, raised his spear and stabbed the bear with all his strength. Seeing that a tragedy was about to happen, Zeus, who was surveying the sky at this time, saw this scene. He couldn't bear to let his son kill his mother himself, so he turned Achatz into a bear by magic. In this way, little Achatz immediately recognized his mother, and the mother and son were happily reunited. In order not to let the mother and son suffer any more accidents, Zeus lifted them to the sky and gave them two glorious positions among the stars, namely Ursa Major and Ursa Minor, which shone brightly in the northern sky. Hera also sent a hunter with two fierce hounds to chase the two bears. This hunter is the shepherd in the sky, and the two hounds he leads are the dog constellation. The ancient Greeks saw this big bear wandering in the sky every night and never fell below the horizon. They think this must be Hera's trick again. It turned out that Hera sent hunters and hounds to hunt down the mother and son, but she still refused to give up. She came to the blue sea again and asked her brother Poseidon for help. Poseidon listened to his sister's story and agreed to her request. So we can see that other constellations have the phenomenon of rising east and setting west. Once in a while, they sank below the horizon and went to Poseidon's territory to rest. Except for two bears. But fortunately, Crystal can stay with her Achatz all the time, so that Hera won't come up with any bad ideas.