"the autumn equinox"

An equinox occurs twice a year, when the centre of the sun is in the same plane as the earth's equator, so that the earth's axis is neither tilted toward or away from the sun.

The Spring equinox is in March, usually 20th-21st, and the Autumn equinox in September, usually 22nd-23rd.

In England, the Autumn equinox marks the Harvest Festival, when Britons give thanks for plentiful harvests of crops. The event has its roots in Paganism, an ancient celtic religion which held that spirits existed in natural objects such as trees and rocks.