Mark the Winter Solstice at the UMass Amherst Sunwheel
The UMass Sunwheel in winter. Photo: umass.edu
Source: UMass News and Media
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 Sunday, Dec. 21, at 7 a.m. and 3:30 p.m. Faculty from the UMass Amherst astronomy department will discuss the astronomical cause of the solstice, and a telescope will be set up to observe the waning gibbous moon, Venus, and the surface of the sun. Heavy rain or snow will cancel the gatherings.
Astronomers mark the start of winter as the moment the sun reaches its southernmost apparent position relative to the stars. The winter solstice is the shortest day of the year 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 official solstice occurs at 10:03 a.m. and the sun reaches its southernmost position at 6:34 p.m. Eastern standard time on December 21. After that moment, the sun begins moving northward, and the days start getting longer.
At the approximately hour-long gatherings, UMass Amherst astronomers Stephen Schneider (sunrise) and Grant Wilson (sunset) will discuss the astronomical cause of the solstice. They 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 at Chankillo in Peru. They 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 solar day of the year is actually Dec. 22.
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 Street) 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.
For more information, please visit the UMass Amherst Sunwheel website.