umass amherst sunwheel

Gathering at the UMass Amherst Sunwheel to Mark the Autumnal Equinox

Sunrise and sunset events on Sept. 22 will usher in the fall

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 Wednesday, 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.

umass amherst sunwheel
UMass Amherst Sunwheel

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

Astronomers mark the change of seasons as the moment when the sun crosses over the celestial equator from the northern hemisphere of the sky to the southern hemisphere. This year the exact minute of the autumnal equinox is 3:21 p.m. Eastern Daylight Time on Sept. 22. At that moment, fall begins 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. It also marks the beginning of six months of daylight at the South Pole and six months of nighttime at the North Pole.

People around the world (other than those at the North and South Poles) will see the sun rise due east and set due west, and stays up for 12 hours and down for 12 hours. This is the origin of the word equinox, which means “equal-night.”

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.

Video: Watch the Autumnal Equinox at the UMass Amherst Sunwheel

For last-minute changes because of weather or other problems, please check the Sunwheel website at: