CLINTON — Summer solstice will be observed at 5:30 p.m. Thursday, the longest day of the year, at the Bickelhaupt Arboretum.

“Solstice” is derived from two Latin words “sol” meaning sun, and “sistere,” to cause to stand still. This is because as the summer solstice approaches, the noonday sun rises higher and higher in the sky on each successive day. On the day of the solstice, it rises an imperceptible amount, compared to the day before. In this sense, it “stands still.”

Since early history this celebration has marked a time of abundance and the grounds of the Arboretum are accordingly lush in color. The Solstice Committee, which includes Joyce Ollie, Liz Clemence, Barbara Hagenson, Michele Scott, Carol Miller, Alma Mariano and Marion Johnson, has planned a drumming experience as visitors gather Thursday, followed by a Medicine Wheel ceremony.

Visitors to the celebration are invited to bring a symbol of the earth — rock, feather, twig, herb, leaf, flower — to be placed in the circle. They are also invited to dress in the one of the colors of the wheel: red, yellow, black or white.

Located at 340 S. 14 St., Clinton, the Arboretum holds equinox and solstice events at the beginning of the seasons as a way to celebrate these changes in weather and as a reminder of the importance of spring, summer, fall and winter.