Happy Fall, everybody! Or, rather, everybody in the northern hemisphere. Southern Hemispherians: Happy Spring to you!
Yesterday was the Autumnal Equinox. Your calendar usually just says “Fall Begins” or “First Day of Fall.” So what does that mean? Yesterday, the Sun appeared directly over the celestial equator on its way to shine more directly on the southern hemisphere, where they had their Vernal or Spring Equinox, prior to their summer. You can think of the equinox as a day of sharing, where we are in the midst of swapping seasons, taking turns having the sun shine directly on our hemisphere to have summer.We had the direct sunlight all summer, so I suppose it is fair we give the southern hemisphere a chance, right? If you don’t feel like sharing, just think of the penguins and feel ashamed of yourself.
The name “equinox” is derived from the Latin aequus (equal) and nox (night). The length of day and night on the equinox are nearly equal (but not quite; variable upon where you live).You can read more about the September equinox here. Also, the standing-up-eggs-on-the-equinox thing is a misconception, which you can read about here, on Bad Astronomy. For more about seasons in general, you could check out here and here.