If you've ever flown over rural parts of North America or spent some time snooping around on Google Earth, you're likely familiar with the green, gridded patchwork of cornfields and grazing paddocks characteristic of modern farmlands. Take this rather monochromatic aerial of my hometown, for example:But depending on where you've flown, you might have seen a less-familiar sight: perfectly circular, almost alien-looking polka dots of bright green freckling the landscape, like this mesmerizing display in Kansas:
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Or these weird, wide circles in Nebraska:
These real-life crop circles are due to center pivot irrigation, where water is sprayed via a giant sprinkler (as much as half a mile long) that pivots around a central point. It's an efficient way to cover a lot of ground with a single sprinkler system and while it's a popular way of irrigating crops in the midwest, it's not widely used in other parts of North America. Here's what it looks like from ground-level:
It turns out agricultural topography is a pretty good way of identifying location. Fields are like a fingerprint for an area's climate, culture, and history. Take this shot from NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), the imaging system aboard the Earth Operating System satellite:
NASA explains this kind of starburst-shaped agriculture is typical of the area. The image was taken above Santa Cruz, Bolivia, and the fields are a result of a settlement scheme. In the middle of each burst or "pie" is a local farming community.Over in Thailand, small slivers of fields like this are quintessential rice paddies. The paddies are "fed by an extensive network of canals that is hundreds of years old," according to NASA:
And if these randomized, misshapen fields look odd to you, you might want to spend some time in Europe. These northwest German fields were first carved out back in the middle ages, when they didn't care so much about nice, neat grids:
So if you ever find yourself floating thousands of feet in the air and aren't sure where you are (runaway hot air balloon? malfunctioning jet pack?) a quick peek at the fields below will help you get your bearings.