Mythology of the constellation Cancer

According to an ancient Greek legend, the figure of a gigantic crab was placed in the nighttime sky by the goddess Hera to form the constellation Cancer. Hera swore to kill Heracles, the most famous Greek hero. Hera attempted to kill Heracles in many different ways, but each time his incredible physical strength allowed him to survive. The Romans called him Hercules.

Hera cast a spell of madness on Heracles, causing him to commit a great crime. In order to be forgiven, he had to perform twelve difficult tasks. One of these tasks was destroying the terrible nine-headed water-serpent, Hydra.

During the battle between Heracles and Hydra, the goddess Hera sent a giant crab to aid the serpent. But Heracles, being so strong, killed the crab by smashing its shell with his foot. As a reward for its service, Hera placed the crab's image in the night sky.