In the arid expanse of northeastern Africa, the Sahara reveals its unique geological features through formations like Jabal Arkanū, which is noted for its impressive ring-shaped structures. Located in southeastern Libya, close to the Egyptian border, Arkanū is part of a cluster of massifs that includes Jabal Al Awaynat, approximately 20 kilometers to the southeast, and other ring structures about 90 kilometers to the west.
Initially believed to be the result of meteorite impacts, recent geological studies have shown that these circular formations are actually of terrestrial origin. The structures at Arkanū formed as magma ascended towards the surface, intruding into the surrounding rock over several events. This process created a complex of overlapping rings of igneous basalt and granite, with their centers generally aligned toward the southwest. Notably, a hat-shaped geological formation composed of sandstone, limestone, and quartz layers borders the complex to the north.
A photograph captured from the International Space Station on September 13, 2025, exhibits the massif casting elongated shadows across the desert landscape. The ridges of Jabal Arkanū reach about 1,400 meters above sea level, standing roughly 800 meters taller than the adjacent sandy plains. The photo also showcases outwash fans of boulders, gravel, and sand radiating from the mountain’s base towards the longitudinal dunes that outline the region.
Two typically dry riverbeds, known as wadis, can be seen weaving through the formation. The harsh environment of this part of the Sahara limits water availability to minimal levels, with past research indicating that southeastern Libya, along with northern Sudan and neighboring regions of Egypt, receives an average annual rainfall of merely 1 to 5 millimeters. Areas around Jabal Arkanū, however, benefit from slight increases in precipitation, with estimates rising to 5 to 10 millimeters annually, hinting at a possible orographic effect from these towering mountains.
The image, taken by an astronaut using a Nikon Z9 camera with an 800-millimeter lens, was enhanced to increase contrast and remove any lens artifacts. Supported by the International Space Station Program, the initiative aims to generate valuable imagery for both the scientific community and the public, making it accessible online. This ongoing effort highlights the collaborative nature of space observation and its contributions to our understanding of Earth’s geological history.