Cancer (the Crab) is a zodiac constellation located in the Northern celestial hemisphere, between Gemini (constellation) to the west and Leo (constellation) to the east. It is the dimmest of the zodiacal constellations. Its brightest star is Tarf. Cancer has two most common shapes. One resembles a slightly irregular letter Y made up of 4 lines; the other is a quadrilateral with 3-4 lines attached to the corners, representing the crab's body and legs.