At the solstices the sun's apparent position on the celestial sphere reaches its greatest distance above or below the celestial equator, about 23 1/2° of arc. At the time of summer solstice, about June 22, the sun is directly overhead at noon at the Tropic of Cancer.
In the Northern Hemisphere the longest day and shortest night of the year occur on this date, marking the beginning of summer. At winter solstice, about December 22, the sun is overhead at noon at the Tropic of Capricorn; this marks the beginning of winter in the Northern Hemisphere. For several days before and after each solstice the sun appears to stand still in the sky, i.e., its noontime elevation does not seem to change from day to day.
Seasons for the Northern Hemisphere
- Vernal Equinox: Mar. 20, 1:26 P.M. EST (18:26 UT*), Sun enters sign of Aries; spring begins.
- Summer Solstice: June 21, 8:26 A.M. EDT (12:26 UT*), Sun enters sign of Cancer; summer begins.
- Autumnal Equinox: Sept. 23, 12:03 A.M. EDT (Sept. 23, 04:03 UT*), Sun enters sign of Libra; fall begins.
- Winter Solstice: Dec. 21, 7:22 P.M. EST (Dec. 22, 00:22 UT*), Sun enters sign of Capricorn; winter begins.