Equinox

views updated Jun 27 2018

Equinox

The Latin meaning of the word equinox is equal night, referring to those two moments in the year when day and night are equal in length. In technical astronomical terms, the equinox is the moment at which the sun appears to cross the equator as a result of Earths rotation around the sun. The vernal (spring) equinox, which occurs as the sun moves from south to north across the equator, takes place around March 21 and marks the beginning of spring. On about September 23, the sun moves from north to south across the equator, marking the autumnal equinox and beginning of autumn. The sun does not actually move around Earth; its apparent path is a reflection of Earths orbital movement about the sun combined with the tilt of Earths axis.

When you gaze upward on a clear night, you see the sky as if it were part of a giant sphere that surrounds earth. Although we know it is Earth that rotates, it appears as though this star-speckled dome turns about us. Early astronomers thought the stars were attached to this giant sphere. Today, astronomers still find it useful to imagine a celestial sphere that surrounds Earth. The extension of Earths north and south poles extend to the north and south celestial poles, and Earths equator can be projected outward to the celestial equator. Time and horizontal angles are measured eastward from the vernal equinoxthe point where the sun crosses the celestial equator in Marchand vertical angles are measured north or south of the celestial equator.

Earths axis of rotation is tilted 23.5° to the plane of its orbit. This tilt causes the seasons, and (from our frame of reference) it makes the sun and the planets, which have orbital planes parallel to Earths appear to move north and south during the course of the year along a path called the ecliptic. Because the ecliptic is tipped relative to Earths equator, it is also tipped relative to the celestial equator. The two points where the ecliptic intercepts the celestial sphere are the equinoxes. When the sun reaches either equinox, it rises in a direction that is due east everywhere on earth. After the vernal equinox, the sun continues to move northward along the ecliptic, rising a little farther north of east each day until it reaches the summer solsticea point 23.5° above the equatoraround June 22. The summer solstice marks the beginning of summer, after which, the sun begins to move southward. It crosses the celestial equator (marking the autumnal equinox) and continues to move southward and rise a little farther south of east each day until it is 23.5° south of the celestial equator at the winter solstice around December 22. It then begins its northward movement back to the vernal equinox.

Equinox

views updated May 23 2018

Equinox

The term "equinox" (from the Latin for equal night) refers to those times during the year in which the length of the day and the night are equal. The equinox occurs twice yearly, at the beginning of spring (around March 21) and the beginning of fall (around September 23). From an astrological perspective, the equinox occurs when the sun appears to be at the point where the celestial equator (the Earth's equator imaginably projected outward into space) meets the eliptical, the path that the sun appears to take as viewed from earth. As people observed the heavens in ancient times, among the first phenomena that became noticeable to them were the apparent movements of the sun, especially the different points on the horizon at which it rose day after day, and the variant length of days. The longest and shortest days (the solstices) and the equinoxes were important markers in the annual calendar, as were the points halfway between each of these days, signaling as they did important activities in the agricultural season. Very early these points became ritualized, the occasions for feasts and celebrations.

In astrology, the spring equinox is the beginning of the new astrological year. At that time the sun enters 0° Aries. At the fall equinox it enters 0° Libra. The planetary configurations at the time of the equinoxes have a particular importance in the interpretations of mundane astrology (the astrology of nations).

The astrological year was largely replaced by the Christian calendar in the West, but came back into use for marking the year with the rebirth of ritual magic in the nineteenth century. It was notable that magician Aleister Crowley named his biannual journal Equinox. However, as with most ritual magicians and astrologers, the equinox, while being an important marker in the calendar, was not a particularly significant point for ritual activity or horoscope interpretation.

Ritual significance was poured back into the equinox within the Neo-Pagan Witchcraft Movement launched by Gerald Gardner in the mid-twentieth century. Gardner revived the eight annual sabbats, two of which occurred on the equinoxes.

Sources:

Cunningham, Scott. Wicca: A Guide for the Solitary Practitioner. St. Paul, Minn.: Llewellyn Publications, 1988.

Farrar, Stewart. What Witches Do. New York: Coward, McCann & Geoghegan, 1971.

Equinox

views updated Jun 08 2018

Equinox

The Latin meaning of equinox is "equal night," the times of the year when day and night are equal in length. In astronomy , the equinox is the point at which the Sun appears to cross the equator as a result of Earth's rotation around the Sun. The vernal equinox, which occurs as the Sun moves from south to north across the equator, takes place around March 21 and marks the beginning of spring. On about September 23, the Sun moves from north to south across the equator, marking the autumnal equinox and beginning of autumn. It is important to realize that the Sun does not actually move; its apparent path is a reflection of Earth's orbital rotation about the sun, and the tilt of Earth's axis.

When you stand on Earth and gaze upward on a clear night, you see the sky as part of a giant sphere that surrounds Earth. Although we know it is Earth that rotates, it appears as though this star-bearing dome turns about us. Early astronomers thought the stars were attached to this giant sphere. Today, astronomers still find it useful to imagine a celestial sphere that surrounds Earth. The extension of Earth's north and south poles extend to the north and south celestial poles, and Earth's equator can be projected outward to the celestial equator. Time and horizontal angles are measured eastward from the vernal equinox—the point where the Sun crosses the celestial equator in March—and vertical angles are measured north or south of the celestial equator.

Earth's axis of rotation is tilted 23.5° to the plane of its orbit . This tilt causes the seasons , and (from our frame of reference) it makes the Sun and the planets, which have orbital planes parallel to Earth's appear to move north and south during the course of the year along a path called the ecliptic. Because the ecliptic is tipped relative to Earth's equator, it is also tipped relative to the celestial equator. The two points where the ecliptic intercepts the celestial sphere are the equinoxes. When the Sun reaches either equinox, it rises in a direction that is due east everywhere on Earth. After the vernal equinox, the sun continues to move northward along the ecliptic and rise a little farther north of east each day until it reaches the summer solstice—a point 23.5° above the equator—around June 22. The summer solstice marks the beginning of summer, after which, the Sun begins to move southward. It crosses the celestial equator (the autumnal equinox) and continues to move southward and rise a little farther south of east each day until it is 23.5° south of the celestial equator at the winter solstice around December 22. It then begins its northward movement back to the vernal equinox.

equinox

views updated May 14 2018

equinox XIV. — (partly through (O)F. équinoxe) L. æquinoctium, in medL. -noxium, f. æqui- EQUI- + nox, noct- NIGHT.
So equinoctial XIV. — (O)F. équinoxial — L. æquinoctiālis.

equinox

views updated May 14 2018

e·qui·nox / ˈekwəˌnäks; ˈēkwə-/ • n. the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20).

equinox

views updated May 29 2018

equinox Either of the two days each year when day and night are of equal duration. They occur on the two occasions, (one spring, one autumn) when the Sun crosses the celestial equator. In the Northern Hemisphere, the Vernal (spring) Equinox occurs around March 21 and the Autumnal Equinox around September 23.

equinox

views updated May 29 2018

equinox the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about 22 September and 20 March).
See also precession of the equinoxes.