Today is the first day of the fall season for the northern half of the world as September 23rd marks the official first day of the fall season .
According to NASA , an equinox “occurs midway between the two solstices , when the days and nights are the least equal .”
Therefore, an equinox is when that day and night each last an equal 12 hours and it also marks the time when the plane of Earth's axial tilt is directly perpendicular to the sun 's radiation.
According to Almanac.com , this year's equinox “the autumnal equinox occurs on Monday, September 23 at 07:50 UTC. The equinox occurs at the same moment worldwide; your clock time depends on your time zone.”
The equinox in Mexico
During the equinox , the pyramid at Chichén Itzá puts on a fantastic show. The pyramid was built by the Mayans around 1,000 years ago and is designed to cast a shadow outlining the body of Kukulkán , the feathered snake god. A snake statue is located at the bottom of the pyramid , and as the sun sets, the sunlight and shadow show the body of the snake joining the head.
![](https://i.ytimg.com/vi/Zvv9EnBuem4/hqdefault.jpg)
Also located in Yucatán, Dzibilchaltún is another legendary Mayan archeological zone where people can witness how the s un rays penetrate through the main castle during every fall equinox .
![](https://i.ytimg.com/vi/nG9DSw0iJNM/hqdefault.jpg)
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