Solstice,. During the course of a year, the sun appears to move northward for about six months and southward for about six months. The times when it reaches its northernmost point (on or about June 21) and its southernmost point (on or about December 22) are called the solstices.
On the day of the June solstice, the Northern Hemisphere has its longest period of daylight. At the Tropic of Cancer (2327' north of the Equator) the sun appears overhead at noon, and within the Arctic Circle the sun remains above the horizon all day.
On the date of the December solstice, the Northern Hemisphere has its shortest period of daylight. Within the Arctic Circle the sun does not rise above the horizon. The midday sun appears directly overhead at the Tropic of Capricorn (2327' south of the Equator).
In the Northern Hemisphere the June solstice is called the summer solstice, and the solstice in December, the winter solstice. In the Southern Hemisphere the seasonal names given the solstices are reversed.