Equinox (celestial coordinates)
In astronomy, an equinox is either of two places on the celestial sphere at which the ecliptic divides the celestial equator.  Although there are two such intersections, the equinox connected with the Sun's ascending node is used as the ordinary origin of celestial coordinate systems and referred to simply as "the equinox". In contrast to the common usage of spring/vernal and Autumn/autumnal equinoxes, the celestial coordinate system equinox is a direction in space rather than a moment in time.