If we go 23 1/2° north of the Equator we encounter a special dashed parallel called the Tropic of Cancer; if we go the same distance south we see its companion the Tropic of Capricorn. The former is at the latitude at which the Sun passes directly overhead on the first day of summer in the Northern Hemisphere, while the latter is where the Sun passes overhead on the first day of Southern Hemisphere summer (or Northern Hemisphere Winter); these evens occur, respectively, about June 22nd and December 22nd.