Tagundnachtgleiche is the German word for equinox, which is the day when the sun crosses the celestial equator, making the day and night equal in length and also marking a change of seasons. The autumn equinox, which falls on September 22nd this year, marks the beginning of autumn. In this case, the German term leaves nothing to be deduced. The word is a short phrase put together – Tag und Nacht Gleiche – meaning “day and night equality”. This year the autumn equinox occurs on September 22nd.