Cancer

Is one of the twelve constellations of the zodiac. Its name is Latin for crab and it is commonly represented as such. Its symbol is  (Unicode ♋). Cancer is small and its stars are faint. It lies between Gemini to the west and Leo to the east, Lynx to the north and Canis Minor and Hydra to the south.


Mythology
Cancer the giant crab, plays a minor role in the Twelve Labors of Hercules. While Hercules was busy fighting the multi-headed monster, Lernaean Hydra, the goddess Hera, who hated her step-son Hercules, sent the Crab to distract him. Cancer tried to kill Hercules, but Hercules kicked Cancer so hard that the crab was sent into the sky.
By other accounts, Cancer grabbed onto the hero's toe with its claws, but barely breaking the rhythm of his great battle with Hydra, Hercules crushed the crab with his foot. Hera, grateful for the little crustacean's heroic but pitiful effort, gave it a place in the sky; but none of its stars were bright because the crab had failed to accomplish its given task. Some scholars have suggested that Cancer was a late add-on to the myth of Hercules to make the Twelve Labors correspond to the twelve signs of the Zodiac.

How to find Cancer in the night sky

Cancer (the Crab)- This is the single hardest constellation to find in the night sky. It requires a completely dark sky. The constellation itself looks like an upside-down "Y". The best way to find Cancer is to find Taurus and Gemini, draw a line through them and continue on to the left until you come to a big empty spot in the sky (it won't take long). The big empty spot is Cancer!