Astronauts use a 25-mile eye in the desert to check their bearings. 👁️

Astronauts use a 25-mile eye in the desert to check their bearings. 👁️ . . . The Richat Structure in Mauritania is 40 km across — visible from the International Space Station. For decades, geologists thought it was a meteor impact crater. Drilling in the 2000s proved otherwise: it's an eroded dome exposing Late Proterozoic rock about 1 billion years old. From the ground it's invisible. You'd walk across it and never notice.