Orbital View: Where All Those Crop Circles Come From

Dalhart, Texas (NASA)

Ria Misra runs through the recent history of irrigation in the U.S., prompted by “NASA releas[ing] a series of pictures showing the rather odd-transformation of this large tract of Kansan farms, changing their shape from rectangles to circles between 1972 and 2015 (with stopovers in 1988 and 2011).” The circles are formed by a center pivot irrigation system:

It’s been around since the 40s. Farmers didn’t start really using them on a large-scale, though, until decades later–and for good reason. The earliest models were giant steel contraptions made of a series of raised sprinklers, supported on towers. They were insanely heavy, easily broken, ridiculously complex to repair, and not very good at sprinkling water evenly.

By the late 60s, however, manufacturers had figured out how to make them lighter, simpler, and more standardized, and over the next decade farmers rapidly began adopting them. By tapping the systems directly into groundwater, farmers were suddenly able to almost completely and easily automate irrigation from deep wells.

More fun circles from The Jefferson Grid here and here.

(Hat tip: )