Today, September 22, at 20h02 (UT) or 22h02 locat time, the astronomical autumn starts. It's the moment the plane of the Earth's equator passes through the center of the Sun's disc. It's also the moment the Sun's apparent geocentric longitude is exactly 180°00'00" and this is called Equinox. Equinox meaning Equi Nox, equal day and night. The autumn period will last 89days and 10hours.
