Snow flies at Carnegie Science Center's annual Snowball Day

They came by the score carrying snowballs in coolers, plastic storage containers and plastic bags, anything that would keep the icy spheroids cold on a day when the temperature was expected to reach 90 degrees.

Most of the children and families that showed up to celebrate the annual Snowball Day at the Carnegie Science Center Tuesday — the first official day of summer — had been saving their snowballs in freezers throughout the region since last winter.

As part of an annual event, the Science Center was celebrating the solstice just as it has every year since 2006 — by helping visitors launch those snowballs into the Ohio River.

“I’ve been bringing the kids to this snowball event since they were little,” said Heather Linton of Cranberry. “In the winter, we collect the snowballs and put them in the freezer and come down on the first day of summer and throw them in the river.”

Linton’s daughter Emily, 19, said she hasn’t outgrown the fun of Snowball Day.

“I’m an adult now but I still like doing it,” she said.

The participants, mostly younger children, used slingshots and other methods to launch their snowballs into the Ohio.

Beth King, 54, East Huntingdon, was holding a plastic bag filled with snowballs as she stood next to her 12-year-old son Nathaniel. Beth, a former crime lab chemist, said she appreciated the science lesson in all this, including the challenge of keeping a snowball cold on a summer day and the physics of how snowballs follow a flight path into the river.

“Anything developed with science can be used for other things,” she said. “It’s not just the original purpose. You use the scientific principles to serve something else, whether it’s physics or biology, adapt and modify is how science works.”

Nathaniel had a simpler view of the proceedings.

“It’s just fun,” he said.

Andy King, 58, Bellevue, brought his 5-year-old grandson Oliver to Snowball Day in keeping with a family tradition. But, he said they forgot to save snowballs from last winter.

“We took ground ice and put it in some cups,” he said.

Meanwhile, Oliver didn’t seem to mind that his grandfather had bent the rules a bit. “I want to do it some more,” he said.

In fact, for anyone who didn’t save a snowball, the Science Center made some with a snow cone machine.

“We have a lot of excited people here with their snowballs, a steady stream since we opened at 10 a.m.,” said Carnegie Science Center program director Brad Peroney.

“We’re really happy with what we’re seeing today. People are having a blast. Winter will be back before you know it so it’s fun to play with the snow today knowing we don’t have to go home and shovel those driveways and clear off the cars,” he said.

General admission was reduced to $5 for the day of the event, which was expected to bring some 1,500 people to the banks of the Ohio River to launch snowballs.