The longest day of the year
Solstice comes from the Latin (sol, sun; sistit, stands). For several days before and after each solstice, the sun appears to stand still in the sky—that is, its noontime elevation does not seem to change.
Solstice, from the Latin for sun stands still, in astronomy, either of the two points on the ecliptic that lie midway between the equinoxes (separated from them by an angular distance of 90°).
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, around June 20 or 21, 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.
The Columbia Encyclopedia, Fifth Edition Copyright © 1993, Columbia University Press. Licensed from Inso Corporation. All rights reserved.