AMHERST — The people celebrating summer Monday night came to learn about astronomy or just to watch the sun set behind one of the several stones that constitute the Sunwheel at the University of Massachusetts Amherst.
There were parents with toddlers on shoulders, seniors with canes and walkers, teenagers huddled in the grass – about 80 of them, plus five dogs.
Built in the 1990s as a project of late UMass astronomy professor Judith Young, the Sunwheel is made up of rocks that mark the directions in which the sun and moon rise and fall at different times of the year.
Stephen Schneider, head of the UMass astronomy department, said Young had the idea after noticing many students thought the sun always rose due east and set due west.
“She thought building one of these structures would give people a chance to be more aware of what’s happening in the sky,” Schneider said.
The Sunwheel may be less than two decades old, but most of the planet’s notable solar calendars are far more ancient. Schneider mentioned Stonehenge, which may date back as many as 5,000 years, and Peru’s Chankillo, a pre-Incan complex that includes 13 towers that may have functioned as a solar calendar.
Solstice and equinox events have taken place at the Sunwheel since its construction. Monday’s event was set to start at 7:30 p.m., and by 7, a crowd was already gathering.
Unlike the enigmatic ancient solar calendars, the Sunwheel has little mystery. It sits in a mowed yard near Warren McGuirk Alumni Stadium. Fifty yards in one direction stood a row of U-Haul trucks; in the other, a few guys kicked around a soccer ball. Children chased each other around the rim of the wheel.
Elaine Cat and Richard Loomis, of Belchertown, said they had been coming to the Sunwheel for some solstices and equinoxes since early in its history.
“There are probably a few more diehard than us, but we’re (here) more than most,” Loomis said.
Near 7:30, Andy Morris-Friedman, a Sunwheel volunteer wearing high white socks and a shirt depicting a Stonehenge-like structure, asked how many people were there for the first time. About 60 percent raised their hands. Morris-Friedman held a globe with a hole cut in its top — the Sunwheel’s donation jar.
A few minutes later, Schneider stood at the center of the wheel and gave a short talk on the basic astronomy of the Sunwheel.
He told the crowd how civilizations around the world have used solar calendars, how before the advent of modern calendars they dictated when crops would be planted and when religious holidays would occur.
He used a hula-hoop, a globe with a wooden stick driven through it and a Styrofoam ball set atop a rod to explain the Earth’s movement around the Sun, the tilt of the Earth’s axis and how the way the Sun hits the tilted Earth causes the seasons.
The crowd was enthusiastic. When the sun emerged from a streak of clouds, a small cheer went up.
Even when Schneider started incorporating math into the discussion, only a couple of people left.
By 8 p.m., the sun was deep orange and hovering just above the horizon. People started taking pictures on their phones. When Schneider finished talking, they mostly split into two lines – one for a solar telescope, the other for the center of the wheel, the optimal spot for picture-taking.
Mike Dickson, of Montague, stood in the telescope line with his children, 7-year-old Amelia and 4-year-old Sam. It was their first time seeing the solstice from the Sunwheel.
“I pretty much had always meant to come out,” Dickson said. “My daughter is 7, and they learned a little about their solstice in first grade, and I thought it’d be fun going with her to see it.”
All three said they learned new things during Schneider’s talk, though Amelia and Sam had trouble naming specifics.
“Did you learn that the Earth revolves around the Sun?” Dickson asked Sam.
“Yes!” he responded.
“I already knew that,” Amelia quipped.
As the sun reddened, painting the sky yellow and orange and purple, Morris-Friedman said the turnout was one of the largest he’d seen. He thinks the events offer a chance to tap into deep-seated human curiosity.
“You get to come here and do what human beings have done since the beginning of time — stare up at the night sky, look at the heavens and try to figure out what our place is in it all,” Morris-Friedman said.
A moment later, at 8:19 p.m., the sun sunk below the pin pricks of trees lining the horizon. The watchers applauded. They weren’t a mass of pagans celebrating a holiday, nor were they farmers depending on the stones to know when to plant crops. This wasn’t a field in England or a desert ridge in Peru. But it was the same sun.
Jack Evans can be reached at jackevan@indiana.edu.