Crop circles have dazzled and baffled fans of UFOs and ornate arable farming for more than a century.
The mystery appeared to be solved when several high-profile cases revealed that the designs were the work of artists and mischief-makers with barrels, planks of wood and a plenty of spare time. Yet not all could be explained.
In recent years crop circle artists have pushed the boundaries of ingenuity, boasting ever-more complex patterns and shapes. Some crop circle designs now feature up to 2,000 shapes, while analysis by mathematicians shown that they can be built on deep patterns and structures that are otherwise invisible to the eye.
But, once again, the case appears to have been cracked. A report in this month’s edition of Physics World by Richard Taylor, director of the Materials Science Institute at the University of Oregon, claims that artists may be using the Global Positioning System, lasers and even microwaves to create their patterns.
According to Taylor, microwaves could potentially be used to make crop stalks fall over into horizontal patterns, increasing the speed and efficiency of artists and perhaps explaining the remarkable detail they have lately achieved.
He says: "Crop circle artists are not going to give up their secrets easily. This summer, unknown artists will venture into the countryside close to your homes and carry out their craft, safe in the knowledge that they are continuing the legacy of the most science-oriented art movement in history."
Take a look at some of the world's most impressive crop circles in our gallery below.