The Tropic of Cancer is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith. This happens once a year, at the time of the June solstice.The imaginary line is called the Tropic of Cancer because when the Sun reaches the zenith at this latitude, it is entering the tropical sign of Cancer. When it was named, the Sun was also in the direction of thecondtellation Cancer. The postcard shows one of many monuments placed along this circle. This one was placed at the East coastline of Taiwan. It looks like a chess pawn, doesn't it?
Thank you, Cadence! I hadn't even known of the Tropic of Cancer before you sent me this card ;)