Mark the Spring Equinox at the UMass Sunwheel

The public is invited to view the sunrise and sunset on the day of the spring equinox among the standing stones of the UMass Sunwheel on Monday, March 20 at 6:45 a.m. and 6 p.m. These Sunwheel events mark the astronomical change of seasons when days and nights are nearly equal in length everywhere in the world, which is the source of the term equinox (for “equal night”), and UMass astronomers will give talks explaining the astronomy of the seasonal changes

Observers standing at the center of the Sunwheel’s standing stones will see the sun rise and set over stones placed to mark the equinoxes, very close to due east and due west. Other structures around the world mark this astronomical change, such as the pyramid at Chichen Itza. The exact time of the equinox this year is 5:24 p.m. Eastern Daylight Time on March 20. This is the moment when the sun crosses the celestial equator, traveling from south to north as viewed from Earth.

On the equinoxes, observers at Earth’s poles see the sun skimming around the entire horizon as six months of daylight begin at the North Pole and six months of night at the South Pole. Observers at the equator will see the sun pass directly overhead at local noon. After the March equinox, Earth’s Northern Hemisphere tilts progressively more toward the sun.

During the approximately hour-long gatherings, UMass Amherst astronomer Stephen Schneider will discuss the astronomical cause of the Sun’s changing position and how the Sunwheel helps track these motions. He will explain the seasonal positions of the sun, moon and Earth, and answer questions about astronomy.

Visitors to the Sunwheel should be prepared for especially wet footing this year. Rain or blizzard conditions cancel the events.