Equinox Comes On September 22

20 September 2016

 - The September equinox will arrive on September 22, 2016 at 14:21 UTC. Although the equinox happens at the same moment worldwide, your clock times will depend on your time zone.

At the equinox, days and nights are approximately equal in length. For us in the Northern Hemisphere, the sun is rising later now, and nightfall comes sooner. We’re enjoying the cooler days of autumn. Meanwhile, south of the equator, spring is about to begin.

What is an equinox? The earliest humans spent more time outside than we do. They used the sky as both a clock and a calendar. They could easily see that the sun’s path across the sky, the length of daylight, and the location of the sunrise and sunset all shift in a regular way throughout the year.

Our ancestors built the first observatories to track the sun’s progress. One example is at Machu Picchu in Peru, where the Intihuatana stone, shown above, has been shown to be a precise indicator of the date of the two equinoxes and other significant celestial periods. The word Intihuatana, by the way, literally means for tying the sun.