In northern Mauritania, on the Adrar Plateau, lies one of Earth's most enigmatic geological formations — the Richat Structure, also known as the "Eye of the Sahara." It's nearly impossible to recognize from the ground, yet from orbit it appears as a giant 40-kilometer (25-mile) bull's-eye pressed into the desert landscape.
French geographers first described it in the 1930s, calling it the Richat "buttonhole." It gained global attention after the Gemini IV mission in 1965, when astronauts Ed White and James McDivitt photographed it from space — that's where the nickname "Eye of the Sahara" comes from.
Scientists initially believed it was an impact crater — large meteorites can leave similar circular marks. Later research proved otherwise: it's a deeply eroded geologic dome. An underground intrusion of igneous material once pushed the overlying rock layers upward. Over time, different rock types eroded at different rates, producing the characteristic concentric ridges known as cuestas. The orange and gray tones reflect the contrast between sedimentary and igneous rocks.
The surrounding region is rich in human history — Paleolithic stone tools, Neolithic cave paintings, and the ruins of medieval towns once used by Saharan caravans have all been found here.
The image is a mosaic captured by the OLI instrument aboard Landsat 8 and Landsat 9 on March 5 and 6, 2026. Composition by Lauren Dauphin, NASA Earth Observatory.