Summer officially begins on Monday, June 20, when the sun goes as far north in the sky as it’s going to get, which is directly over the Tropic of Cancer at 23.44 degrees north.
The Tropic of Cancer (also known as the Northern Tropic) is the north circle of latitude at which the sun appears directly overhead at it most northern point. The equivalent line of latitude south of the Equator is called the Tropic of Capricorn.
The region between these two lines is the “tropics.” The term tropic is derived from a Greek word meaning a turn, change of direction or circumstances, because the sun appears to turn back at the solstices.
These two circles of latitude are named after the constellations Cancer and Capricorn, based on ancient astrological conditions that are not pertinent to modern astronomy. Nevertheless, the terms Tropic of Cancer and Tropic of Capricorn are part of our culture.
The summer solstice takes place around June 21 every year, and the winter solstice takes place around Dec. 21. The summer solstice represents the change from spring to summer, and the winter solstice represents the change from fall to winter. Around the days at which the solstices take place we have the times of longest daylight (summer solstice) and the longest night (winter solstice).
