Lsummer is officially behind us. Lovers of summer and aperitifs on the beach will have to put their soul in peace. Although this year the autumn equinox is scheduled for 23 September at 3.03 Italian time. And not today, September 21stas we learned in school.
The solar year does not coincide with that of the calendar
The solar year, in fact, does not coincide with that of the calendar. Because? It is not really true that the Earth takes exactly 365 days to complete an orbit around the Sun. Our Planet takes 365,256 days, which is our calendar year to which about six hours must be added.
The leap year – one every four years – comes precisely to compensate for these differences. And he makes up for the hours lost previously. This is why the autumn equinox, as well as the other seasons, undergoes this calculation.
The autumn equinox in Yucatan, Mexico on September 30, 2003. Credit: EPA PHOTO / EFE / Lucio Blanco // EPA PHOTO / EFE / Lucio Blanco //
In general, then, the autumn equinox tends to be delayed due to Kepler’s II law: the path of our planet slows down the further it is from the star (aphelion). And this happens when it is summer in our hemisphere.
Why we talk about the “autumn equinox”
What does the autumn equinox consist of? This is the exact moment in which day and night have the same duration. The name derives from the Latin aequinoctium which means, in fact, same night. It corresponds to that moment of the earth’s revolution around the Sun when the latter is at the Zenith of the equator.
iO Donna © REPRODUCTION RESERVED