AMHERST, Mass. (WWLP)– Saturday is the Autumnal Equinox, beginning at 2:50 AM, ushering in the change from summer to fall.

Two public programs are being held at the standing stones of the UMass Amherst Sunwheel to observe sunrise and sunset on Saturday, September 23 at 6:30 AM and 6:00 PM.

UMass Amherst astronomer Stephen Schneider will give a presentation explaining the differences between an equinox and a solstice, how people have celebrated seasonal changes across centuries and cultures, and the significance of standing stones.

The equinox occurs when the sun crosses the celestial equator from north to south as seen from Earth, marking the start of fall in the Northern Hemisphere. The sun will rise due east and set due west, stays up for 12 hours and down for 12 hours.

If there are clear skies, a telescope will be set up before the morning session to view Venus in its crescent phase and possibly Jupiter and its moons (beginning about 6 a.m.).

During the evening session, a solar telescope will be set up before sunset to safely view the sun’s surface. Afterward, there will be an opportunity to look at the waxing gibbous moon.

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.