Center-pivot irrigation systems are used worldwide for producing crops
Satellite view of center pivot irrigation systems, Wadi As-Sirhan Basin, Saudi Arabia, 2013
Center pivot irrigation systems are easily seen not only from space, but from an airliner when you fly over the central United States (and many other places in the world). The circles might look tiny from the sky, but down on the land surface, these devices can be huge, stretching thousands of feet.
In these systems, water is pumped from a well in the center of the circle from an underground aquifer and distributed through a giant pipe hundreds of yards long; the whole systems pivots around a central point. Each triangular strut must have an engine to turn the wheels, and they must all turn at a slighly different speed.