At first, she thought what she was seeing was something ordinary.

"As I pulled out of my driveway, I noticed it," Theresa Sinclair, 58, Silvis said. "I thought it was an airplane that was very low."

It was about 6:30 a.m. March 23, and Ms. Sinclair was on her way to her job at the Rock Island Arsenal. What she saw through the open window of her car was a triangular shape in the sky, with bright red, green and white lights along its edges, outlining the shape.

When Ms. Sinclair first saw it, the triangle appeared to be over a high-rise building at the intersection of 10th Street and Crosstown Avenue. She couldn't say what distance it actually was away from her, but it appeared big.

She said she then looked away because she was concentrating on driving west on Crosstown, but when she looked up again, it was moving -- fast.

"It just, like, zipped to Jewel (grocery store), then it zipped to over by Colona Road," Ms. Sinclair said.

She stopped her car at the intersection of Crosstown and 10th Street and got out to have a better look.

"I decided I was intrigued at this point," Ms. Sinclair said. "Then I looked up, and it was gone."

The whole episode only took three or four minutes, she said.

The whole time she observed the object, she did not hear anything like the sounds of jet engines or helicopter blades. It appeared to stay the same distance away from her the whole time.

"I heard nothing, I heard nothing at all," Ms. Sinclair said.

And apparently neither did anyone else.

Local and federal authorities, including the National Weather Service, the Federal Aviation Administration and Quad City International Airport said they received no reports of anything odd in the sky during that time.

Ms. Sinclair said she did not report it either. "I was just so taken aback by it," she said.

She did tell some of her co-workers about it, though. Jokes about little green men ensued.

"You laugh, but stranger things happen," she told them.

The next day, Ms. Sinclair went out at the same time, but did not see anything. There wasn't a second show.

She said Wednesday that she's not on any medications, had not had any alcohol, nor suffered any recent blows to the head.

Many officials, and some local astronomers, also could not or, in some cases, would not, explain what she saw.

"Chances are she wasn't seeing what she thinks she saw," said Black Hawk College professor Richard Harwood, who teaches geology, geography and astronomy.

He said that Saturn and Jupiter would have been visible in the sky as bright stars that morning. It's possible one of them could have appeared moving because Ms. Sinclair's vehicle was in motion.

"In her case, who can say," Mr. Harwood said. "Nobody else saw it, it's hard to tell."

When asked what she thought it was, Ms. Sinclair replied with a laugh that it was an unidentified flying object, or UFO.

But then she added, "I can't say."

"I would like to have been able to say it was a plane or a weather balloon," she said. "But I don't know. It was unidentifiable."