Eye of the Sahara: Copernicus Captures the Richat Structure’s 31-Mile Bull’s-Eye

Eye of the Sahara: Copernicus Captures the Richat Structure’s 31-Mile Bull’s-Eye

In the heart of Mauritania’s Sahara, an enormous circular formation stands out from orbit like a deliberate target etched into the sand. A recent image from the European Space Agency’s Copernicus Sentinel-2 mission reveals the Richat Structure—commonly called the Eye of the Sahara—as a striking set of concentric rings about 31 miles (50 km) across.

At ground level the rings are often difficult to see: shifting dunes, heat shimmer and irregular terrain obscure much of the pattern. From space, however, the structure reads clearly as ripples frozen in rock. For decades its near-perfect circularity prompted speculation that it might be an impact crater.

Fieldwork and detailed analysis disproved the impact hypothesis. Geologists found no evidence of shocked quartz, impact melt, or other markers of a high-energy collision. Instead, the Richat Structure is best explained as a deeply eroded geological dome: a broad uplift of layered sedimentary rock that has been sculpted by wind, occasional water flow and sand abrasion.

Over millions of years, softer rock layers were worn away while harder, erosion-resistant units—especially quartzite-rich sandstones—remained as ridges. The exposed concentric rings therefore act like a natural cross section of Earth’s crust, revealing older strata toward the center. Parts of the sequence are estimated to be at least 100 million years old.

False-color composites from the Copernicus Sentinel-2 mission help tell this story by highlighting differences in rock type and vegetation. Resistant quartzite sandstones show up in red and pink tones outlining the rings; darker bands mark softer, more deeply eroded units; and small purple flecks in the southern sector reveal sparse trees and shrubs following a dry riverbed that winds into the Eye.

Seen from orbit, the Richat Structure is a dramatic reminder of the power of uplift and erosion to shape landscapes over geological time. The Copernicus imagery not only makes the formation visually spectacular but also provides scientists with a clearer map of its composition and structure.

Image Location: Adrar Region, Northern Mauritania
Data Source: European Space Agency — Copernicus Sentinel-2