Google wore her autumn with a new Doodle that reminds us of the day and the fact of the autumn equinox. On 11: 20 this morning Wednesday September 23 (Greek time), the autumn equinox occurs in the northern hemisphere. 
The northern hemisphere belongs to Greece, and the autumn equinox marks the astronomical start of this autumn.
In the southern hemisphere spring begins.
The equinox is happening two times a year, when the earth's axis is aligned parallel and at right angles to the sun's axis.
At this particular moment, Heliums lies in a straight line with the earth's vertical equator, with the result that night and day are of equal duration at any point on earth surfaces.
Equinox occurs around 20 March and September 22. At this point the deviation of the earth's axis is zero to the sun.
Google wouldn't let the fact go unnoticed, and so if you look at the machine's home page today search you will see the corresponding Doodle.
With information by WikiPedia.
