We'll pretend you were waiting on the OFFICIAL start of Fall to start slurping PSLs and chunkin 'punkins. Well now you can! The official equinox rings in a new season Monday at 2:19 PM ET. That is when the sun's rays are perpendicular to the equator.
Most associate the equinox with equal day and night. Because sunlight gets refracted through the atmosphere, it will appear that the sun has risen when it really hasn't - that's the difference between an even split of day and night.
If you're thinking "haven't we already done this?" Yes, well, sort of. Meteorologists did it on September 1st, as a way to keep record books similar year in and year out. The sun's rays are good and all but most people don't feel like we're really INTO Fall until the clocks budge. We've still got some time on that one: