Enjoying EarthSky? Subscribe.

117,250 subscribers and counting ...

Sun at zenith over Earth’s equator on the September equinox

Simulated image above: Planet Earth, from the vantage point of the sun, at the instant of the September 2014 equinox.

Tonight for September 22, 2014

The 2014 northern autumnal equinox (southern spring equinox) takes place on Tuesday, September 23 at 2:29 UTC. If you could be standing on the sun at that moment, at the instant of the 2014 autumnal equinox, you’d see the part of Earth shown on the image at the top of this post facing your direction.

Although the equinox happens at the same instant for everyone worldwide, the clock time for the equinox varies by time zone. In the U.S., the equinox come on Monday, September 22. The time will be 10:29 p.m. EDT, 9:29 p.m. CDT, 8:29 p.m. MDT or 7:29 p.m. PDT.

At this special moment – the instant of the September equinox – the midday sun will be at zenith, or straight overhead, at the Earth’s equator. That’s the meaning of this equinox. At the September equinox sun crosses the sky’s equator, going from north to south. Because the path of the sun is heading southward, this equinox signals the beginning of autumn in the Northern Hemisphere and spring in the Southern Hemisphere.

On the day of the equinox, the sun rises due east and sets due west all over the world, with everyone worldwide receiving approximately the same amount of day and night.

As soon as the beginning of October, however, that’ll change dramatically. By then, the sun will rise noticeably south of due east and will set noticeably south of due west. That’ll mean shorter days and longer nights for the Northern Hemisphere, and longer days and shorter nights in the Southern Hemisphere.

After the equinox, the sun and the migrating birds will continue to travel southward to the southern climes. Arctic sea ice will begin to freeze; Antarctic ice will start melting. The great wheel of the seasons will continue to turn.

How to celebrate? Try to watch as the sun rises due east and sets due west on this day of the equinox.

Read more: Everything you need to know about the September equinox 2014

Day and night sides of Earth at instant of September 2014 equinox

Worldwide map, showing the day and night sides of Earth at the instant of the September 204 equinox (2014 September 23 at 2:29 Universal Time)

Worldwide map, showing the day and night sides of Earth at the instant of the September 2014 equinox (2014 September 23 at 2:29 Universal Time)

Fastest sunsets of the year around equinox time