Cancer is a constellation of the zodiac. The genitive, used to form star names, is Cancri.
 
 During the battle of the powerful hero Hercules with the terrible Hydra, the multi-headed monster, the Crab was sent to distract the warrior during the fight. However Hercules crushed the Crab with his foot. As a reward for his efforts, Hera placed him among the stars. The Zodiac symbol represents the crab's claws.
 
 This is the story of Greek mythology that makes the little crab represented by a constellation in the sky, chance or not, so small is its participation in history that the constellation is also the weakest of the 13 zodiacal constellations.
 Popularly known as Cancer (from Latin), it is a constellation with very faint stars and few objects to be seen. Its fame is due to the zodiac and the beautiful group M44. This constellation appears between Gemini and Leo, two masterpieces from our sky.
 
 Millennia ago the sun reached the summer solstice when it was facing this constellation. So, above it there was, in the north latitude, what we call the Tropic of Cancer.