Once a month for roughly 20 years, Douglas Wolfe has stood out on the corner of Broadway and 16th Street with his telescopes.

Wolfe is a "Sidewalk Astronomer" -- a worldwide group of the astronomers who bring telescopes to public streets.

"We give people a chance to see the universe that they live in when they least expect it," Wolfe told ABC10 while out there Friday night.

For Wolfe, that means that one weekend a month ("every time the moon is shaped like a 'D,'" he explained), he sets up on the corner across from the Tower Cafe showing people the moon and planets.

Despite his several years doing sidewalk astronomy, many locals are still surprised to learn about his service.

"I was just walking around and happened to see this cool group hanging around," Robert Bridges said after using one of Wolfe's telescopes to look at the moon. "I'm like, 'sweet, I'm down, I'm just going to get food anyways.'"

The telescopes Wolfe uses are made out of plywood and cardboard -- an idea, he said, that came from the Sidewalk Astronomer founder and Sacramento-native, John Dobson.

Asked why Wolfe continues to come out and do this, he simple replied: "Because it's fun."

Wolfe and his astronomer friends will be set-up on Broadway on Saturday night starting around 8:30 p.m.