Aug. 31, 2006 — -- For centuries they've puzzled people by their curious appearance.
They crop up in fields across the globe, in patterns ranging from the simple circle to the DNA double helix.
Right now in America, it's that time of year again.
That's right, it's crop circle season.
This year they're popping up all over the Midwest, with recent sightings in Geneseo, Ill.; Sandyville, Ohio; and Huntingburg, Ind.
And the list goes on.
"But the real question that comes up is, what exactly are they?" said Stan Friedman, a nuclear physicist and author of the book "Crash at Corona: The Definitive Study of the Roswell Incident."
That's the question that always has everyone talking.
From crop circle designers and top-level researchers to the baffled farmers who usually find them, nobody really knows the origin of crop circles.
Remember, as the Gallup Polls tell, three-fourths of people in this country believe in paranormal activity.
Just in case that affects whom you choose to believe.
"There's still a massive amount of people out there who really believe that these things are made by aliens," said John Lundberg, a world-renowned crop circle architect from the United Kingdom.
"The crop circle phenomenon obviously feeds off other cultural mythologies."
Lundberg has been building crop circles for more than a decade in southern England.
Trained in fine art, he says he began building circles as an extension of his artwork.
"When I first went out to start making them, I also sort of thought there might be some extraterrestrial explanation," he said.
Others, including Colin Andrews, a world-leading crop circle expert -- yes, such a thing does exist -- have done extensive research that they say proves that not all crop circles come from humans.
Andrews and his team conducted a study in central-southern England during 1999-2000, which assessed more than 200 circles.
That study showed around 80 percent of crop circles to be man-made with the remaining number unaccounted for.
"We found a lot of evidence that really for a first time separated the nonsense of man-made circles from the real phenomenon," he said.
According to Andrews, crop circles not made by humans exhibit a number of peculiar traits.