For all practical purposes, fall probably started three weeks ago with the pumpkin spice world takeover. That's more noticeable than this scientific equinox stuff anyway.

But do you know what's actually happening to the earth today?  Here is the Cliffs Notes version of what the Autumnal Equinox really means.

Today is the first official day of fall, meaning the earth is as straight up and down as it will ever be. In summer, the sun's equator lines up with our Northern Hemisphere, and in winter the sun's equator lines up with the Southern Hemisphere.

The earth's tilt makes that happen. Today, on the first day of fall, the earth is basically stuck between those periods, and instead of tilting one way or another it's straight up and down. I know this from my second grader, and from verifying that she was correct on Weather.com.

There are all sorts of myths about other things that can happen on this Autumnal Equinox, like if you stand on the equator you won't cast a shadow because the sun is right on top of you and there is no angle for a shadow.

But even if it's noon and you're on the equator, the act of looking down at your toes will cast a shadow of your head, right? Fascinating.

Night and day are both about 12 hours long today, and from here the days get shorter and the nights get longer. Winter is coming.

But for now, grab a pumpkin spice latte or a pumpkin ale, jump into a big pile of leaves, and start shopping for your Darth Vader Halloween costume. Fall is here.

Sunny and 93 for the first day of fall? Come on Texas. You can cool off any minute now. Fall has officially arrived.