Solstice

Solstice, two times each year when the sun is on the points of the ecliptic farthest from the equator. At the summer solstice, in late June (about June 22), the sun is directly overhead at noon on the Tropic of Cancer; at winter solstice, in late December (about Dec. 22), it is overhead at noon on the Tropic of Capricorn. In the Northern Hemisphere these celestial events are used as the traditional commencement of summer and winter. They are also the days of the longest and shortest daylight hours.

See also: Equinox.