crop circle appeared in a rice field in indonesia

Indonesian rice farmers in Slemen, Yogyakarta, got quite a surprise Sunday morning when they discovered that overnight a large crop circle had mysteriously formed in one of their fields.
The circle, which also includes internal geometric patterns of a triangle and smaller circles, has an overall diameter of nearly 90 feet, according to The Jakarta Post.

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.
"It is impossible that this was made by the wind or any animal," he added.
Whether crafted by humans or aliens, thousands of crop circles have been reported all over the world for many decades, but with a higher number recorded in England. And they're not always circular, with some of the more intricate and complex ones looking like strange animals or even scientific symbols or DNA sequences.
The patterns are generally created by something that flattens various crops, like rice, wheat and rye, and they're usually discovered by farmers in the early morning where they didn't exist the night before.
In some cases, people have admitted being the architects of crop circles, by using ropes and boards to flatten the crops. But even that doesn't explain all crop circles everywhere, which leaves many of them unexplained.
According to Moedji Raharto, the previous head of the Bosscha Observatorium, Indonesia's oldest observatory, "If this really is the work of a UFO or extraterrestrial beings, it is almost 100 percent certain they would have left some sort of trace behind.
"The chemical composition of the soil itself could reveal the origin of the phenomenon. For example, when a meteorite enters the atmosphere and forms a crater, it leaves traces of elements that are not common to the area," Moedji said. He added that similar results could be expected in a soil analysis of the Yogyakarta circle.
This is the first crop circle reported in 2011. Slemen police chief Iwan Ramani wouldn't commit either way on whether the circle in his jurisdiction was crafted by a UFO, humans or even a natural phenomenon. He's still investigating.