What is the eye of the Sahara
Executive summary
The "Eye of the Sahara" is the Richat Structure, a roughly 50-kilometre-wide circular geological dome in central Mauritania that looks like a bull’s‑eye from space and has been a familiar astronaut landmark since early missions (50 km diameter) [1]. Geologists say it is a deeply eroded dome of sedimentary and igneous rocks at least ~100 million years old, sculpted by uplift and subsequent wind, sand and water erosion rather than by a meteor impact [2] [3].
1. A satellite bull’s‑eye visible from orbit
From space the Richat Structure presents concentric rings and contrasting colours that make it instantly recognisable — recent Sentinel‑2 imagery from September 2025 shows the full 50 km diameter and both natural‑colour and false‑colour views used by ESA to highlight rock types and erosion patterns [4] [1]. The feature sits on the Adrar plateau and the surrounding darker area in the images is exposed sedimentary rock standing some 200 m above nearby dunes of the Erg Ouarane [1].
2. Not a crater — a geologic dome shaped by uplift and erosion
Early speculation suggested an impact origin, but scientific work now favours a structural dome: uplift and exposure of layered rocks including erosion‑resistant quartzite sandstones and an underlying alkaline igneous complex, with central rings about 80 m tall and older rocks toward the centre [1] [5]. Reporting and geology summaries describe magmatic activity and hydrothermal alteration among the rocks, supporting endogenous geologic processes rather than a meteor strike [5] [2].
3. Age, composition and the forces that made it
Multiple sources report rocks in the Richat area are at least about 100 million years old, with a mixture of sedimentary layers and igneous units (gabbroic and other magmatic rocks) that were later unearthed by erosion [2] [5] [3]. The outer rings are formed of more erosion‑resistant quartzite sandstones (reddish/pink shades in false colour), while valleys of less‑resistant rock appear darker — the ringed relief therefore reflects differential erosion of layered rock types [1].
4. Astronauts, landmarks and cultural echoes
The Eye of the Sahara has long been a navigational marker for astronauts since the Gemini era and remains striking in modern Earth‑observation datasets such as Copernicus Sentinel‑2 and ESA’s Earth from Space releases [2] [1]. The structure has also fed popular imagination: travel and adventure events (ultramarathons) use the Eye as a focal point, and speculative or mythic claims (e.g., Atlantis associations) appear in non‑scientific media — these cultural threads are separate from the geological explanations reported by scientists [6] [7].
5. What images tell us — and what they don’t
Satellite images clearly show scale, ring geometry and lithologic contrasts, and false‑colour composites accentuate quartzite ridges and sedimentary relief [1] [4]. However, imagery alone cannot establish formation mechanisms or precise ages; those conclusions rest on field geology, petrography and stratigraphic work discussed in scientific summaries [5] [2]. Available sources do not mention any newly published peer‑reviewed papers overturning the dome/erosion interpretation.
6. Popular claims versus scientific summaries
Public outlets and popular science pieces emphasize the visual drama and antiquity of the structure [8] [7]. They sometimes repeat older impact hypotheses or speculative cultural links; by contrast, geology‑focused reporting and ESA/NASA‑linked descriptions present the dome and erosion model with specific observations about rock types and heights of central rings [1] [5] [2]. Readers should note those two currents: visual/popular fascination and the geologic interpretation based on field and remote‑sensing evidence.
7. Limitations, open questions and how to follow developments
Current reporting in these sources states the accepted interpretation (eroded dome, ~100 million years old) and documents its appearance in recent Sentinel‑2 imagery [1] [4] [3]. Available sources do not mention any definitive new field studies that would change age estimates or the basic genetic model, so future peer‑reviewed geological work could refine timing, igneous history or erosion chronology [2] [5]. To track updates, follow ESA/Copernicus image releases and geology journals cited by science communicators like HowStuffWorks that summarise primary literature [1] [5].
If you want, I can pull the specific ESA and Sentinel‑2 images referenced here and summarize the captions and technical notes, or assemble a short reading list of the scientific papers and field reports mentioned in these summaries (not all of which are in the present source list).