Ecliptic (redirected from ecliptics)

ecliptic (ēklĭp`tĭk, ĭ–), 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 path. The ecliptic is the principal axis in the ecliptic coordinate system. The two points at which the ecliptic crosses the celestial equator are the equinoxes. The obliquity of the ecliptic is the inclination of the plane of the ecliptic to the plane of the celestial equator, an angle of about 23 1-2°. The constellations through which the ecliptic passes are the constellations of the zodiac.

---

ecliptic

Great circle that is the apparent path of the Sun among the constellations in the course of a year; from another viewpoint, the projection on the celestial sphere of the orbit of Earth around the Sun, which intersects the plane of the celestial equator at the vernal and autumnal equinoxes. The constellations of the zodiac are arranged along the ecliptic.

---

ecliptic

1. Astronomy

a. the great circle on the celestial sphere representing the apparent annual path of the sun relative to the stars. It is inclined at 23.45? to the celestial equator. The poles of the ecliptic lie on the celestial sphere due north and south of the plane of the ecliptic

b. (as modifier): the ecliptic plane

2. an equivalent great circle, opposite points of which pass through the Tropics of Cancer and Capricorn, on the terrestrial globe

3. of or relating to an eclipse

---

ecliptic [i′klip·tik]

(astronomy)

The apparent annual path of the sun among the stars; the intersection of the plane of the earth's orbit with the celestial sphere.

The plane of the earth's orbit around the sun.

---

Ecliptic 

the great circle on the celestial sphere along which occurs the apparent annual motion of the sun or—more precisely—the apparent annual motion of the center of the sun. Since the apparent annual motion of the sun reflects the actual motion of the earth about the sun, the ecliptic may be regarded as the intersection of the celestial sphere and the plane of the earth’s orbit.

The plane of the ecliptic is inclined to the plane of the celestial equator by an angle of ε = 23° 27’ 8″.26 – 0.4685t, where t is the number of years that have elapsed since the beginning of 1900. The equation is valid for several centuries after the 20th century. The angle of inclination, which is called the obliquity of the ecliptic, varies periodically over hundreds of thousands of years.

The term “ecliptic” is associated with the fact, known since ancient times, that solar and lunar eclipses occur only when the moon is near one of the points where its orbit intersects the ecliptic. These points on the celestial sphere are called the lunar nodes. The ecliptic passes through 12 constellations, which are known as the zodiacal constellations. The plane of the ecliptic is the fundamental plane in the ecliptic system of celestial coordinates.