The official first day of fall, otherwise known as the autumnal equinox, is this weekend in the Northern Hemisphere. According to Encyclopedia Britannica, it is one of only two days, the other being the vernal equinox, when the sun is directly above the Equator, essentially dividing night and day into equal portions.

Fall weather is soon going to be hitting the Northeast and just in time as the official start to fall — the autumnal equinox — is about to arrive. The fall — or autumnal — equinox can land on Sept. 22 or 23 depending on the year This year,

So is the autumnal equinox, which marks the end of astronomical summer and the first day of fall in the Northern Hemisphere. The exact time of the fall equinox changes slightly each year. This year, the equinox arrives Sept.