March equinox

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Related to March equinox: September equinox, June solstice

March equinox

[′märch ′ē·kwə‚näks]
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

vernal equinox

vernal equinoxclick for a larger image
i. That point of intersection of the ecliptic and the celestial equator occupied by the sun as it changes from a south to a north declination, on or about March 21. Also called the March equinox or the first point of Aries.
ii. That instant the sun reaches the point of zero declination when crossing the celestial equator from south to north.


equinoxclick for a larger image
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.
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References in periodicals archive ?
Even the earliest date of March 26 is well after the March equinox. Thus, all of the hypothetical observational Nisan 15 dates fulfill the conditions of TB Sanhedrin 11b.
The March equinox was one of the most important dates in ancient Egyptian and Persian calendars.
So during one visibility period of Saturn we can see the shadows moving from west to east and from either north to south (around the March equinox on Saturn) or south to north (around the September equinox).
In 2006 there were 75 days between perihelion and the March equinox. One quarter of a year averages 91.3 days.
The eclipsed Moon will rise just north of due east, because this eclipse comes shortly before the March equinox (when the Sun and therefore any eclipsed Moon are on the celestial equator).
The rule most people remember is that Easter falls on the first Sunday after the first full Moon following the March equinox. In practice, Roman Catholic and Protestant churches follow a method of calculation adopted with the Gregorian calendar reform of 1582.
I refer to the full Moon nearest the September equinox (or nearest the March equinox for those living south of the equator), the one commonly called the Harvest Moon.
This comes just nine nights after the March equinox, when (for observers north of the tropics) the ecliptic makes the steepest possible angle with the horizon at sunset.