Saudi Arabia has worked for nearly 30 years to irrigate the Syrian Desert, where it grows wheat and other crops. To do so, it has drilled through the desert floor and drawn water from underground aquifers, which irrigates fields through center-pivot irrigation — creating the green circles seen here. This operation, in the Wadi As-Sirhan Basin, covers roughly 7,800 square kilometers (3,000 square miles) and each circular field is about one kilometer (0.62 miles) across. | Daily Overview