equinox

equinoxcelestial sphere showing the positions of the autumnal and vernal equinoxes

e·qui·nox

E0190400 (ē′kwə-nŏks′, ĕk′wə-)n.1. Either of two points on the celestial sphere at which the ecliptic intersects the celestial equator.2. Either of the two times during a year when the sun crosses the celestial equator and when the length of day and night are approximately equal; the vernal equinox or the autumnal equinox.

[Middle English, from Old French equinoxe, from Medieval Latin aequinoxium, from Latin aequinoctium : aequi-, equi- + nox, noct-, night; see nek^w-t- in Indo-European roots.]

equinox

(ˈiːkwɪˌnɒks; ˈɛkwɪˌnɒks) n1. (Astronomy) either of the two occasions, six months apart, when day and night are of equal length. See vernal equinox, autumnal equinox2. (Astronomy) another name for equinoctial point[C14: from Medieval Latin equinoxium, changed from Latin aequinoctium, from aequi- equi- + nox night]

e•qui•nox

(ˈi kwəˌnɒks, ˈɛk wə-)

n. the time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length all over the earth and occurring about March 21 (vernal equinox) and Sept. 22 (autumnal equinox). [1350–1400; Middle English < Medieval Latin equinoxium, for Latin aequinoctium=aequi- equi- + noct-, s. of nox night + -ium -ium¹]

equinoxChanges in seasons occur as the position of the Earth in relation to the sun changes. Equinoxes and solstices mark the beginning of opposite seasons in the Northern and Southern Hemispheres. For example, the June solstice marks the beginning of summer in the Northern Hemisphere and of winter in the Southern Hemisphere. The September equinox marks the beginning of fall in the Northern Hemisphere and of spring in the Southern Hemisphere.

e·qui·nox

(ē′kwə-nŏks′)1. Either of the two moments of the year when the sun crosses the celestial equator. The vernal equinox occurs on March 20 or 21, and the autumnal equinox occurs on September 22 or 23. The days on which an equinox falls have about equal periods of sunlight and darkness.2. Either of the two points on the celestial sphere where the apparent path of the sun (known as the ecliptic) crosses the celestial equator. Compare solstice.

equinox

“Equal night,” the two points at which the ecliptic intersects the celestial equator to produce the seasonal spring (vernal) equinox and autumnal (fall) equinox.

Thesaurus

Noun	1.	equinox - either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal lengthcosmic time - the time covered by the physical formation and development of the universeMarch equinox, spring equinox, vernal equinox - March 21autumnal equinox, fall equinox, September equinox - September 22
	2.	equinox - (astronomy) either of the two celestial points at which the celestial equator intersects the eclipticequinoctial pointastronomy, uranology - the branch of physics that studies celestial bodies and the universe as a wholecelestial point - a point in the heavens (on the celestial sphere)vernal equinox - (astronomy) the equinoctial point that lies in the constellation of Piscesautumnal equinox - (astronomy) the equinoctial point that lies in the constellation of Virgo

Translations

春分或秋分昼夜平分点

equinox

(ˈekwinoks) noun the time when the sun crosses the equator, about March 21 and September 23. 昼夜平分点，春分或秋分

equinox

(ē`kwĭnŏks), either of two points 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
..... Click the link for more information. where 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
..... Click the link for more information. 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. This occurs about Mar. 21, marking the beginning of spring in the Northern Hemisphere. At the autumnal equinox, about Sept. 23, the sun again appears to cross the celestial equator, this time from north to south; this marks the beginning of autumn in the Northern Hemisphere. On the date of either equinox, night and day are of equal length (12 hr each) in all parts of the world; the word equinox is often used to refer to either of these dates. The equinoxes are not fixed points on the celestial sphere but move westward along the ecliptic, passing through all the constellations of the zodiaczodiac
[Gr. zoion=animal], in astronomy, zone of the sky that includes about 8° on either side of the ecliptic. The apparent paths of the sun, the moon, and the major planets all fall within this zone.
..... Click the link for more information. in 26,000 years. This motion is called the precession of the equinoxesprecession of the equinoxes,
westward motion of the equinoxes along the ecliptic. This motion was first noted by Hipparchus c.120 B.C. The precession is due to the gravitational attraction of the moon and sun on the equatorial bulge of the earth, which causes the earth's axis to
..... Click the link for more information. . The vernal equinox is a reference point in the 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.
..... Click the link for more information. .

Equinox

(religion, spiritualism, and occult)

The equinoxes (from the Latin for “equal night”) are the two points in the year when the length of the day is equal to that of the night. These are the vernal (spring) equinox, which occurs on the first day of spring (on or around March 21), and the autumnal equinox, which takes place on the first day of fall (on or around September 23). In astronomical terms, the equinoxes occur when Earth reaches a place in its orbit where, from our point of view, the Sun appears to be situated at the exact intersection of the celestial equator and the ecliptic. The vernal equinox is especially important for Western astrologers, who regard the Sun’s position against the backdrop of the stars at the spring equinox (the vernal point) as the place where the zodiac begins.

Sources:

Filbey, John, and Peter Filbey. The Astrologer’s Companion. Wellingborough, Northamptonshire, UK: Aquarian Press, 1986.Tester, Jim. A History of Western Astrology. New York: Ballantine, 1987.

Equinox

the moment at which the sun’s center crosses the celestial equator in the course of the sun’s apparent annual path along the ecliptic. At the time of the equinox, the length of the day is almost equal to that of the night over the entire earth, except near the poles. The difference is a matter of only a few minutes and results from refraction and the great angular diameter of the sun.

The point at which the sun’s center crosses the equator as the sun travels from the southern hemisphere to the northern hemisphere is called the vernal equinox. The point at which the sun’s center crosses the equator as the sun travels in the opposite direction is the autumnal equinox. Since the time between two successive transits of the sun through the same equinox (the tropical year) is not the same as the length of the calendar year, the equinox changes each year relative to the start of the calendar day. In a common year the equinox begins 5 hours 48 minutes 46 seconds later than the preceding year, while in a leap year it begins 18 hours 11 minutes 14 seconds earlier. The equinox may therefore extend over two successive calendar days. At the present time (second half of the 20th century), the sun passes through the vernal equinox on Mar. 20 and 21 (start of astronomical spring in the northern hemisphere) and the autumnal equinox on Sept. 23 (start of astronomical autumn in the northern hemisphere). These dates are given in the New Style for the start of the day in Moscow time.

Hipparchus (second century B.C.) discovered that the equinoxes slowly shift along the ecliptic in the direction of the apparent annual path of the sun. This shift, owing to the precession of the earth’s axis of rotation, has a period of about 26,000 years. In 1737, J. Bradley found that the earth’s axis experiences nutation, as a consequence of which the equinoxes complete oscillatory motions with a period of 18.6 years relative to their mean positions as determined by their precessional motion. Changes in the celestial coordinates of the heavenly bodies are related to the changing positions of the equinoxes. Star catalogs give the positions of stars for given vernal equinoxes of different epochs.

equinox

[′ē·kwə‚näks] (astronomy) Either of the two points of intersection of the ecliptic and the celestial equator, occupied by the sun when its declination is 0°. Also known as equinoctial point. That instant when the sun occupies one of the equinoctial points.

equinox

Positions of sun and the earth at spring and autumnal equinoxes.i. One of the two points of intersection of the ecliptic and the celestial equators, occupied by the sun when its declination is 0°. Also called an equinoctial point. That point occupied on or about March 21, when the sun's declination changes from south to north, is called the vernal equinox, spring equinox, March equinox, or first point of Aries that point occupied on or about September 23, when the declination changes from north to south, is called the autumnal equinox, September equinox, or first point of Libra. Equinox is often used to mean vernal equinox, when referring to the origin of measurement of right ascension and celestial longitude. At the time of equinox, the duration of day and night is the same or equal.
ii. That instant the sun occupies one of the equinoctial points.

equinox

either of the two occasions, six months apart, when day and night are of equal length

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Synonyms for equinox

noun either of two times of the year when the sun crosses the plane of the earth's equator and day and night are of equal length

Related Words

noun (astronomy) either of the two celestial points at which the celestial equator intersects the ecliptic

Synonyms

Related Words