´╗┐The TROPIC OF CANCER ---> referred to as the Northern Tropic which is the most northerly circle of latitude on the Earth at which the Sun may appear directly overhead at its culmination. The said event occurs once every year at the time of the Northern solstice, when the Northern Hemisphere is tilted toward the Dun to its maximum extent.

It is called Tropic of Cancer because when the Sun reaches  the zenith at this latitude, it is entering the astrological sign of Cancer (summer solstice in the Northern hemisphere). When it was named that way, the Sun was also in the direction of the constellation Cancer (which is the Latin word for CRAB).