The public is invited to observe sunrise and sunset of the longest day of the year among the standing stones of the UMass Amherst Sunwheel on Tuesday June 21 at 5:00 a.m. and 7:30 p.m. UMass Amherst astronomers will describe how the Sunwheel works and explain the astronomical cause of the solstice at the roughly hour-long gatherings.

For astronomers, the solstice takes place at the moment when the Sun reaches its northernmost point relative to the stars, which occurs this year at 5:13 a.m. EDT. This marks the astronomical start of summer in the Northern Hemisphere and winter in the Southern Hemisphere.

On the date of the solstice, daylight is longest and nighttime is shortest in the Northern Hemisphere. At local noon in Amherst (about 12:52 pm EDT), the Sun will be the highest it gets in the sky all year round, about 71 degrees above the horizon. The Sun passes straight overhead on this day only for people living along the Tropic of Cancer.

The Sunwheel's standing stones mark the changing positions of the Sun and Moon throughout the year, much like ancient calendar-stone sites found around the world. On the date of the June solstice, the Sun rises and sets farthest north at spots along the horizon marked by tall standing stones. Other stones mark the position of the Sun at the equinoxes and winter solstice.

The position where the Sun rises and sets on the horizon changes so gradually around the date of the solstice that it looks as though it is in the same place every day for more than a week. This is the origin of the word solstice, which means "stationary Sun." Sunwheel visitors who stop in on their own will be able to see the sun rising and setting over the summer solstice stones from roughly June 16-26.

Location: The UMass Sunwheel is located south of McGuirk Alumni Stadium, just off Rocky Hill Road. The Sunwheel can easily be reached from the center of Amherst, following Amity St. to the west, on the right hand side of the road about 1/4 mile after crossing University Drive.

Visitors to the Sunwheel should be prepared for wet footing and mosquitoes. The events will be canceled in the event of heavy rain.

More Information: For more information on the U.Mass. Sunwheel, click here. For more information on the Moon's 18.6-year cycle, click here.

DIRECTIONS TO THE SUNWHEEL:

For directions from out of town, click here.

For a map showing the Sunwheel on the UMass Amherst campus, click here.

DATES OF SUNWHEEL GATHERINGS:

For the dates and times of Sunwheel gatherings, click here.