An aerial image of a crop circle photographed in March 2010 in Wiltshire, England. Credit: Last Refuge/Robert Harding World Imagery/Corbis

A crop circle that appeared a few days ago in rural Indonesia has tens of thousands of people flocking to the site for a glimpse of the mystery.

Many strained to see or photograph the nearly 100-foot diameter pattern featuring circles and triangles. Some people fainted or prayed, considering it a sign from above. The country’s National Atomic Energy Agency was even called in to inspect the site, and declared it harmless and free of radiation, much to the relief of those selling souvenirs to the gathering crowds.

So what made the strange pattern?

Some believe that mysterious energy lines or supernatural vortices are to blame; still others attribute them to freak wind patterns.

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One popular theory is that they are created by extraterrestrials who are trying to give us signs, warnings, or other information. The extraterrestrial explanation is of course very popular, as Lee Speigel of AOL News noted: “One resident, Cahyo Utomo, speculated that the odd piece of rice field artwork wasn’t man-made. ‘The circles were there since yesterday morning. I think they were left by an alien spaceship,’ he said.”

If this explanation is true, it seems very strange that aliens would go to the trouble of traveling across the universe to our pale blue dot just to press down some plants in various shapes and then leave. Surely if an alien civilization is advanced enough to master space travel, it can devise more effective ways of communicating with us.

There’s only one known source for crop circles: humans. (In fact, I have personally investigated and made several crop circles, as I discuss in my 2010 book "Scientific Paranormal Investigation: How to Solve Unexplained Mysteries.") Many people believe that crop circles have been reported for centuries, mistakenly citing a folktale from 1678 in which an English farmer told a worker with whom he was feuding that he “would rather pay the Devil himself” to cut his oat field.

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In fact, crop circles only date back about 30 years. The mysterious patterns first appeared in the British countryside, and their origin remained a mystery until September 1991, when two men, Doug Bower and Dave Chorley, confessed that they had created the patterns for decades as a prank. They never claimed to have made all the circles — many were copycat pranks done by others — but their hoax was responsible for launching the crop circle phenomena.

Clearly, something made the patterns. Whether aliens or hoaxers, they are probably enjoying the publicity, and the souvenir vendors are delighted.