A crop circle is a sizable pattern created by the flattening of a crop such as wheat, barley, rye, maize, or rapeseed. Crop circles are also referred to as crop formations, because they are not always circular in shape. While the exact date crop circles began to appear is unknown, the documented cases have substantially increased from the 1970s to current times. Twenty-six countries reported approximately ten thousand crop circles in the last third of the 20th century. Ninety percent of those were located in southern England.[1] Many of the formations appearing in that area are positioned near ancient monuments, such as Stonehenge. According to one study, nearly half of all circles found in the UK in 2003 were located within a 15 km (9.3 …ver más…

There have been cases in which researchers declared crop circles to be "the real thing", only to be confronted with the people who created the circle and documented the fraud.[43] In his 1997 book The Demon-Haunted World: Science as a Candle in the Dark, Carl Sagan discussed alien-based theories of crop circle formation. Sagan concluded that no empirical evidence existed to link UFOs with crop circles.[44] Many others have demonstrated how complex crop circles can be created.[32][45] Scientific American published an article by Matt Ridley,[19] who started making crop circles in northern England in 1991. He wrote about how easy it is to develop techniques using simple tools that can easily fool later observers. He reported on "expert" sources such as the Wall Street Journal who had been easily fooled and mused about why people want to believe supernatural explanations for phenomena that are not yet explained. Methods of creating a crop circle are now well documented on the Internet.[32]
Among others, paranormal enthusiasts, ufologists, and anomalistic investigators have offered hypothetical explanations that have been criticized as pseudoscientific by skeptical groups like the Committee for Skeptical Inquiry.[46][47][48][49]
Responding to local beliefs that "extraterrestrial beings" in UFOs were responsible for crop circles appearing in Indonesia, the government and the National