When does an equinox occur?
Equinox is either of the two instants of time at which it is no-shadow-
noon, at a location on the equator of the Earth.
It occurs on about March 21 or about September 23, every year.
March equinox is called vernal equinox and September equinox is
In 2017, these instants, in GMT, are nearly
Mar 20, 20:26 and Sep 22, 20:02.
A MON AVIS : The difference for half a year appears to be more
than the axial-precession-delay of
These equinox locations are in the Pacific ocean.