The great circle of the heavens which the sun appears to us to describe in the course of a year, in consequence of the earth's motion round that luminary. It is inclined to the equinoctial at an angle of nearly 23° 28′, called the obliquity of the ecliptic, and cuts it in two points diametrically opposite to each other, called the equinoctial points. The time when the sun enters each of these points (which occurs about the 20th of March and 23d of September, respectively) is termed the equinox, day and night being then equal; at these periods, especially about the time of the vernal equinox, storms, called the equinoctial gales, are prevalent in many parts of the globe. The two points of the ecliptic, which are each 90° distant from the equinoctial points, are called the solstitial points. That great circle which passes through the equinoctial points and the poles of the earth, is called the equinoctial colure; and that which passes through the solstitial points and the poles of the earth, the solstitial colure.