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

Astronomer on hand to explain why day and night length varies by season
Sunwheel
UMass Amherst Sunwheel

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

The winter solstice occurs when daytime is shortest in the Northern Hemisphere. On this date the sun rises and sets at its most southerly spot along the horizon, over the southeasterly and southwesterly stones in the Sunwheel, respectively. The sun actually reaches its southernmost position at 11:19 p.m. local time on Dec. 21, and then begins moving northward. For those living in time zones to the east, the day of the equinox will occur on Dec. 22.

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 December 22.

If it is clear during the morning session, a telescope will be set up to observe the waning crescent moon. In the evening session a telescope will be set up to safely observe the surface of the sun.

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 (Amity St.) about one-quarter mile west 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.