Wiki Page, B7: World Geography and Civilizations, term 1-1: Seasons

Wiki Page
2013-10-21T10:39:26-06:00

As the earth revolves, its position relative to the sun is not straight up-and-down. Rather, the earth is tilted 23 1/2 degrees on its axis. Because of the earth's tilt, the Tropic of Cancer at 23 1/2 North and the Tropic of Capricorn at 23 1/2 South mark the boundaries of the places on the earth that receive the most direct sunlight.

The earth's tilt also means that sunlight strikes different parts of the planet more directly at certain times of the year.

solstices - June 21 and December 21, the days when the sun appears directly overhead at the Tropics of Capricorn and Cancer. These days mark the seasonal change of summer and winter.

equinoxes - March 21 and September 23, the days when the sun, at noon, appears directly overhead at the Equator. These days mark the seasonal change of spring and fall and around these dates the lengths of day and night are nearly equal everywhere on the earth.