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Related to September equinox: December solstice, June solstice

EQUINOX. The name given to two periods of the year when the days and nights are equal; that is, when the space of time between the rising and setting of the sun is one half of a natural day. Dig. 43, 13, 1, 8. Vide Day.

References in periodicals archive ?
During the March equinox (also known as vernal equinox in reference to spring) and the September equinox (autumnal equinox) the length of nigh and day become equal.
The rings of Saturn lie in the equatorial plane of the planet, which means that at the March equinox on Saturn, the Sun rises for the northern side of the rings and sets for the southern side, whereas at the September equinox the Sun rises for the southern side of the rings and sets for the northern side.
The other two Bihus are - Kongali Bihu, which is celebrated in October and is associated with the September Equinox, and the Bhogali Bihu in January, which is associated with the January Solstice.
The pagan Prichards would have seen the September equinox - an astronomical point whose name comes from the Latin meaning equal night - as something truly special.
We've just passed the September equinox, and that's generally considered to be the start of the autumnal gale season, so be prepared for a few more gusts.