Celebrate the Autumnal Equinox at the UMass Amherst Sunwheel on Sept. 22

AMHERST, Mass. – The public is invited to join UMass Amherst astronomer Stephen Schneider among the standing stones of the campus Sunwheel to observe sunrise and sunset on Thursday, Sept. 22 — the autumnal equinox. These Sunwheel events mark the astronomical change of seasons when days and nights are nearly equal in length around the world. The gatherings will be held in person at 6:30 a.m. and 6:00 p.m.

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From the UMass Sunwheel in Amherst, observers standing at the center of the Sunwheel see the sun rise and set over particular stones placed to mark the equinoxes.

Schneider will explain the design of the Sunwheel and compare it to ancient sites around the world. He will explain the astronomical cause of the sun’s changing alignments during the hour-long gatherings. He will also explain the seasonal positions of Earth, the sun and moon and discuss various myths and confusing aspects of the equinox.

The autumnal equinox marks the astronomical change of seasons when days and nights are nearly equal in length around the world—giving us the word equinox for equal night.

Astronomers mark the change of seasons at the moment the sun crosses over the celestial equator from the northern hemisphere of the sky to the southern hemisphere. This year that happens at 9:03 p.m. Eastern Daylight Time on Sept. 22. That moment marks the beginning of fall in the Northern Hemisphere and spring in the Southern. On the day of the equinox, an observer located on Earth’s equator will see the sun pass directly overhead at local noon, and it marks the beginning of six months of daylight at the South Pole and six months of nighttime at the North Pole. In places other than the poles, the sun rises due east and sets due west.

The UMass Amherst Sunwheel is located south of McGuirk Alumni Stadium, just off Rocky Hill Road (Amity St.) about one-quarter mile south of University Drive. Visitors to the Sunwheel should be prepared for wet footing, and mosquito repellent is highly recommended. Heavy rain cancels the events, but the talks will be given if there are clouds or light rain.

For last-minute changes because of weather or other problems, please check the Sunwheel website at www.umass.edu/sunwheel.