Mark the Spring Equinox on March 20 at the UMass Amherst Sunwheel

The public is invited to celebrate the beginning of spring at the University of Massachusetts Amherst’s Sunwheel on Sunday, March 20. To mark the day of the vernal equinox, UMass astronomers will give talks explaining the astronomy of the seasonal changes at 6:45 a.m. and 6 p.m., while viewing sunrise and sunset among the standing stones of the Sunwheel.

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On the day of the March equinox, the sun crosses the celestial equator, passing from south to north. This year, the sun crosses the equator at 11:33 a.m. EDT on March 20, marking the moment when astronomical spring begins in the Northern Hemisphere and autumn in the Southern Hemisphere.

The term, “equinox,” derives from equi-nox (equal-night), and on the equinox, the length of nighttime is nearly equal to the length of daytime. Over the previous six months, the sun has been rising in the southeast and setting in the southwest, but on the equinox it rises due east and sets due west, before continuing its northward motion. The equinox also marks the start of six months of daylight at the North Pole, and six months of nighttime at the South Pole.

The shifting position of the rising and setting sun has been the basis for calendar circles like the Sunwheel built all over Earth for thousands of years. The presentations will explain how the Sunwheel was designed to mark these changes along with those of the moon, and relate them to the astronomical motions of the sun, moon, and Earth. Other questions about astronomy are also welcome!

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 cold temperatures and wet footing. Rain or blizzard conditions cancel the events. Donations are welcome to help with the cost of additional site work and future events.

For more information, please visit the UMass Amherst Sunwheel website.