UMass Amherst Sunwheel and Sky-Watching Events Mark the Winter Solstice on Dec. 21

Sunwheel drawing
Sunwheel drawing

AMHERST, Mass. – The public is invited to witness sunrise and sunset associated with the winter solstice among the standing stones of the UMass Amherst Sunwheel on Thursday, Dec. 21 at 7 a.m. and 3:30 p.m. Heavy rain or snow will cancel the gatherings.

Sunwheel events mark the astronomical change of seasons. The winter solstice occurs when nights are longest and days are shortest in the Northern Hemisphere and the sun rises and sets at its most southerly spot along the horizon, over the southeasterly and southwesterly stones in the Sunwheel, respectively.

At the hour-long gatherings, UMass Amherst astronomer Stephen Schneider will discuss the astronomical cause of the solstice. He will explain the seasonal positions of Earth, the sun and moon, and the design of the Sunwheel and other calendar sites such as the Temple of Karnak in Egypt and Chankillo in Peru.

He will also answer other astronomical questions, such as why the earliest sunset occurs about two weeks before the solstice and the latest sunrise about two weeks later, or why the longest day of the year is actually Dec. 22. If it is clear for the evening session, telescopes will be set up to observe the crescent moon and to safely observe the surface of the sun.

Even though the instant when the sun reaches its southernmost position occurs at11:28 a.m. local time on Dec. 21, Sunwheel visitors who stop in on their own will be able to see the sun rising and setting over the winter solstice stones from roughly Dec. 16–26. This is because around the time of the solstice (which means stationary sun) the sun appears to rise at a fixed spot on the southeast horizon and to set in a fixed southwest direction for more than a week.

The UMass Amherst Sunwheel is located south of McGuirk Alumni Stadium, just off Rocky Hill Road about one-quarter mile south of University Drive. Visitors to the Sunwheel should be prepared for freezing 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.

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