Pennsylvania light in sky
©Jason Plotkin
Dave Dietz points out one of the photographs on his computer of the UFO he witnessed and took pictures of outside his Thomasville home last week.

Dave Dietz of Thomasville saw something in the night sky last week, and he's still not sure what.

Dietz isn't some kind of nut. He doesn't have posters of UFOs in his office. He doesn't believe Bigfoot is stalking the woods beyond his Jackson Township home. He doesn't believe in paranormal nonsense.

He's a scientist by trade, an environmental geologist. By avocation, he's an amateur astronomer. His office bookshelves contain tomes about geology and astronomy. There's not an "I want to believe" poster in sight.

And so, he doesn't know how to explain what he saw one recent night while driving home from Abbottstown.

"It was something in the sky, and it was unidentified," Dietz, 48, said. "What I saw was something I can't identify."

That makes it a UFO.

It was between 10:30 and 11 p.m. when he saw something in the southern sky. He looks at the sky a lot, having an interest in the heavens, and he could tell immediately that what he saw was something he hadn't seen before.

It was a group of bright orbs, much brighter than the brightest star in the sky, Sirius, the Dog Star. They weren't planets; they weren't in a part of the sky that any planet would appear in. He didn't know what they were.

They hovered, in a kind of V-shape, and turned around. They weren't moving.

When he got home, he stood in the backyard of his 18th-century home and watched the lights. They were moving around, but not in any way that would indicate any kind of aircraft he's familiar with.

His wife had never seen anything like it before, either. Their 10-year-old son, Nicholas, came out and watched, too.

Dietz snapped photos, about 40 in all. The photos show lights that don't appear to be like any aircraft or easily explained phenomena.

At one point - a moment captured in one of his photos - the grouping of bright lights seemed to expel one of the lights.

"It shot out," he said. "It reminded me of one of those marshmallow guns."

He stayed in the yard until about 1 a.m., watching the lights, and then went to bed. The next day, he looked at the pictures and tried to figure out what it was he had seen in the sky.

"As a scientist, the first thing I tried to do was debunk it," he said.

He checked satellites on the Internet and found none that would be visible to the naked eye in that area of the sky. Even if it were a satellite, he said, satellites do not move in the way the lights he saw moved. He checked to see whether the space shuttle was orbiting; shuttles were earthbound, he found.

He checked the location of the International Space Station. It could have been that, he said. But it would have been in another part of the sky and would have been visible only for a few minutes.

Nothing he checked could have been the lights, he said.

"I still haven't been able to debunk it," he said.

He reported it to the Mutual UFO Network at MUFON.com, but he hasn't heard anything back.

"I'm not saying I saw aliens," he said. "But with all of the billions of galaxies and stars in the universe, it's foolish to think we're the only people out there."

MUFON lists UFO sightings in Pennsylvania. Some of them seem plausible. Others not so much. On the other hand, former President Jimmy Carter once said he saw a UFO.

A message left at MUFON's Fort Collins, Colorado, headquarters went unanswered. (The automated telephone operator at MUFON says, "To report an abduction experience, please press 2.")

MUFON has reported a wave of UFO sightings in Pennsylvania.

The Bucks County Courier Times in suburban Philadelphia recently ran a story about four separate reports of UFOs.

York County 911 reported it did not receive any calls from other people who may have seen the lights. The York Airport didn't receive any reports either.

"On occasion, we'll hear rumors about things," said operations manager Rick Fuess. "One of the things we hear about are helicopters."

Dietz said what he saw didn't look anything like any helicopter, or any other aircraft, he's aware of.

"All I'm saying is I saw something and it was unidentified," he said. "Being a scientist and an astronomy nut, does that give me more credibility or less credibility?"