solstice

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solstice

(sŏl`stĭs) [Lat.,=sun stands still], in astronomy, either of the two points on the eclipticecliptic
, the great circle on the celestial sphere that lies in the plane of the earth's orbit (called the plane of the ecliptic). Because of the earth's yearly revolution around the sun, the sun appears to move in an annual journey through the heavens with the ecliptic as its
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 that lie midway between the equinoxesequinox
, either of two points on the celestial sphere where the ecliptic and the celestial equator intersect. The vernal equinox, also known as "the first point of Aries," is the point at which the sun appears to cross the celestial equator from south to north.
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 (separated from them by an angular distance of 90°). At the solstices the sun's apparent position on the celestial spherecelestial sphere,
imaginary sphere of infinite radius with the earth at its center. It is used for describing the positions and motions of stars and other objects. For these purposes, any astronomical object can be thought of as being located at the point where the line of sight
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 reaches its greatest distance above or below the celestial equator (see equatorial coordinate systemequatorial coordinate system,
the most commonly used astronomical coordinate system for indicating the positions of stars or other celestial objects on the celestial sphere. The celestial sphere is an imaginary sphere with the observer at its center.
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), 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 (see tropicstropics,
also called tropical zone or torrid zone, all the land and water of the earth situated between the Tropic of Cancer at lat. 23 1-2°N and the Tropic of Capricorn at lat. 23 1-2°S.
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). 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 Dec. 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.

Solstice

(religion, spiritualism, and occult)

The solstices (from the Latin sol, meaning “sun,” plus sistere, meaning “to stand still”) are the longest and the shortest days of the year. In the Northern Hemisphere, from the summer solstice to the winter solstice the sunrise occurs a little farther north each day. On the day of the winter solstice, the Sun pauses (“stands still”) in its gradual northward movement and begins to move south. This continues until the next summer solstice, when the Sun once again pauses and reverses direction. In the tropical zodiac, the solstices correspond with the moment the Sun enters 0° Cancer (summer solstice) and 0° Capricorn (winter solstice).

Solstice

 

the instant at which the center of the sun is at the northernmost or southernmost point on the ecliptic. The term “solstice” is also applied to these points on the ecliptic, as is the term “solstitial point.” When the sun is at the northernmost point on the ecliptic, both the instant in time and the point are known as the summer solstice; the sun’s declination here is +23°27’. When the sun is at the southernmost point on the ecliptic, the instant and the point are called the winter solstice; the sun’s declination in this case is – 23°27’.

Near the solstices, the sun’s declination changes very slowly (seeCELESTIAL COORDINATES), since in this region the sun’s motion along the ecliptic is almost parallel to the equator. As a result, the midday altitude of the sun remains almost constant for several days—hence the term “solstice.”

The interval of time between two successive passages of the sun through the same solstitial point does not coincide with the calendar year. For this reason, the instant at which the sun is at the solstitial point occurs at a different time each year relative to the beginning of the calendar day. In a common year, the solstice occurs 5 hours 48 minutes 46 seconds later than in the preceding year. In a leap year, the solstice occurs 18 hours 11 minutes 14 seconds earlier than in the preceding year. Thus, the solstice may occur on two successive dates. At the present time, in the second half of the 20th century, the summer solstice is on June 21 or 22, and the winter solstice is on December 21 or 22.

The summer solstice is the beginning of the astronomical summer in the northern hemisphere, and the winter solstice is the beginning of the astronomical winter in the northern hemisphere. In the northern hemisphere, the length of the day is greatest at the time of the summer solstice and is least at the time of the winter solstice. In the southern hemisphere, the shortest and longest days, respectively, are observed at these times.

solstice

[′sälz·təs]
(astronomy)
The two days (actually, instants) during the year when the earth is so located in its orbit that the inclination (about 23½°) of the polar axis is toward the sun; the days are June 21 for the North Pole and December 22 for the South Pole; because of leap years, the dates vary a little.

solstice

solsticeclick for a larger image
i. The time when the sun reaches its maximum distance from the equator. It is the point where the sun's declination reaches a maximum value. The two solstices are the summer solstice, which is on June 20 to 23 in the Northern Hemisphere, and the winter solstice, which is on December 20 to 23, also in the Northern Hemisphere. The other definition of solstice is that it is one of the two points of the ecliptic farthest from the celestial equator. One of the two points on the celestial sphere occupied by the sun at maximum declination. Also called a solstitial point.
ii. The instant at which the sun reaches one of the solstices.

solstice

1. either the shortest day of the year (winter solstice) or the longest day of the year (summer solstice)
2. either of the two points on the ecliptic at which the sun is overhead at the tropic of Cancer or Capricorn at the summer and winter solstices