Usually, yesterday is the Autumnal Equinox, AKA the first day of Fall. Not this year, as Joe Rao of Space.com reports in Fall Begins Monday: Equinox Myth Debunked.
Sick of long, hot summer days? Well, you're in luck. Astronomically speaking, autumn is about to begin in the north.If you don't believe Rao, National Geographic confirms it in Autumnal Equinox 2014: Facts About the First Day of Fall.
On Monday (Sept. 22), at 10:29 p.m. EDT (0229 Sept. 23 GMT) autumn begins astronomically in the Northern Hemisphere. This also marks the start of spring in the southern half of the globe.
This date is called an equinox, from the Latin for "equal night," alluding to the fact that day and night are then of equal length worldwide. But that is not necessarily correct.
The true days of day-night equality always fall after the autumnal equinox and before the vernal equinox, Geoff Chester, a public affairs specialist with the U.S. Naval Observatory in Washington, D.C., explained to National Geographic News in 2005.The true date of day-night equality will be September 26, not today. Just the same, the official day is today. Happy Equinox!
The difference is a matter of geometry, atmosphere, and language.
"Those factors all combine to make the day of the equinox not the day when we have 12 hours [each] of light and darkness," Chester said.