Those otherworldly crop circles may not have been caused by aliens after all. Instead, think physics: A study in Physics World points to the possibility that the patterns could be caused by Earth-bound microwaves, lasers, and GPS. Maybe.

Formations in fields have been documented more than 10,000 times in the late 20th century. They have been credited to everything from paranormal activity to human hijinks to the weather--and in some cases, even wallabies (more on that later).

Further fueling the mystery is that the farmland designs are done in secret, usually in the dark--and often by jokers who want to make it seem like Martians were at work. It wasn't until 1991 that the first pranksters admitted to have created at least some of the crop circles as a UFO hoax. What has confounded scientists is trying to explain just how the art is done without any marks left by the makers, all typically in just one night.

The question led researcher Richard Taylor of the University of Oregon to rule out at least some traditional explanations of the tools involved in creating the circles. Taylor contends that in the modern age, planks and ropes (to flatten plants) and even bar stools to jump from one area to another undetected, are just too cumbersome to produce results in the comparatively brief period of their creative incubation.

Instead, he argued that latter-day crop-circle auteurs use high-tech gadgets such as GPS monitors to place the shapes and magnetrons (tubes that use electricity and magnetism to generate intense heat) to cause the crop stalks to fall over at high speed.

Can any of this speculation be proven? Not really--at least not until a certified crop-circle fabricator steps forward to claim responsibility and reveal the various tricks of the trade. But as Matin Durrani, editor of Physics World, put it, at least Taylor gives us an explanation that doesn't hinge on the handiwork of alien life forms. Taylor "is merely trying to act like any good scientist--examining the evidence for the design and construction of crop circles without getting carried away by the side-show of UFOs, hoaxes, and aliens," Durrani writes.

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Fair enough. Still, some crop circles have a fairly reasonable explanation. The Harry Potter "maize maze" was designed by a York, England, farmer, not little green men.

Meanwhile, some formations in Australian poppy fields have been blamed on wallabies. Yes, those kangaroo-like animals apparently eat the legally grown opiate, become "high as a kite," and hop around to create their own circle work.

But all the speculation over the origins of these works of art designed for the aerial viewer shouldn't obscure the central nature of their achievement: They are, in a word, crop-tastic.