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Space-made record shows rocky rings in the Sahara, ancient geological origin, rare vegetation, and marks associated with human presence in an extremely low rainfall area.
An image taken by an astronaut aboard the International Space Station recorded a circular rock formation, approximately 25 kilometers wide, in southeastern Libya.
Known as Mount Arkanu, or Jabal Arkanū, the structure is located near the border with Egypt and stands out in the Sahara Desert due to its concentric rings, its origin linked to ancient magmatic processes, and the presence of vegetation in an area of extremely low rainfall.
Mount Arkanu draws attention in Nasa image
The photograph was taken on September 13, 2025, and published by the NASA Earth Observatory as image of the day on November 28, 2025.
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In the record, the rocky rings appear surrounded by dunes and sandy plains, while shadows cast by the ridges help highlight the formation’s relief.
Mount Arkanu rises almost 1,400 meters above sea level and about 800 meters above the surrounding sandy plains.
This altitude difference allows for the observation, from Earth’s orbit, of the circular organization of the rocks and the lower areas between the massif’s walls.
To the north of the structure, a formation composed of layers of sandstone, limestone, and quartz creates the appearance of a “hat” over part of the complex.
The description is used by NASA to differentiate this sedimentary portion from the ring complex, formed mainly by igneous rocks, such as basalt and granite.
Circular structure in the Sahara not born from impact
For years, circular formations of this type were associated with the possibility of meteorite impacts.
In Arkanu’s case, however, field surveys cited by NASA indicated a terrestrial origin.
The accepted explanation is that magma repeatedly rose towards the surface and infiltrated existing rocks, creating a sequence of superimposed rings.
According to the NASA Earth Observatory, “repeated intrusion events produced a series of overlapping rings, with their centers roughly aligned towards the southwest.”
The agency states that this process gave rise to the ring complex currently seen in southeastern Libya.
The exact age of the formation was not established in the consulted sources.
NASA reports that the geological process is related to ancient forces that acted beneath the desert but does not provide a precise dating for the end of the magmatic intrusions.
Therefore, the safest way to describe it is as a preserved record of ancient geological processes, without attributing a specific date.
Rare vegetation appears in hyper-arid area
The environment around Mount Arkanu is among the driest stretches of the Sahara.
Research cited by NASA, with data from the Tropical Rainfall Measuring Mission, indicates that southeastern Libya, neighboring areas of Egypt, and northern Sudan receive, on average, only 1 to 5 millimeters of rain per year.
Near Mount Arkanu and nearby massifs, accumulations can reach something around 5 to 10 millimeters annually.
The difference is small in absolute numbers, but NASA associates this increase with a modest orographic effect, caused by the presence of elevations in the middle of the desert landscape.
Orographic precipitation occurs when air masses encounter elevated areas, rise, cool, and can favor the formation of clouds and rain.
At Mount Arkanu, this mechanism does not alter the hyper-arid condition of the region but helps explain the existence of areas with grasses, shrubs, and some trees within and around the structure.
The areas shaded by the rocky walls also contribute to the permanence of this vegetation.
Instead of being directly exposed to heat and solar radiation throughout the day, some internal areas receive shade for longer.
With the occasional water from rare rains, these stretches offer less severe conditions than the open dunes around them.
Dry riverbeds cut through the rocky rings
Two wadis, or generally dry riverbeds, cross the structure and appear in the image as channels cutting through part of the rings.
These courses only receive water on specific occasions, after rare rains, but their erosive action over time has opened passages in the outer walls of the massif.
These openings show how the formation continued to be reshaped after its magmatic origin.
Water does not circulate permanently, but runoff episodes were sufficient to transport sediments, erode rocks, and create connections between the interior of the massif and the desert plain.
Rock art and human presence in the desert
In addition to its geological interest, Mount Arkanu also appears in records related to human presence in the desert.
The neighboring massif of Jabal Al Awaynat, also known as Uweinat or Uwaynat, is located about 20 kilometers southeast and is part of the same regional set of formations used as reference by groups that crossed this area of the Sahara.
Part of the rocky walls of these massifs preserves ancient engravings, known as petroglyphs.
According to a report published by Live Science based on Earth Observatory data and archaeological references, there are images of human figures and animals, including bovines and giraffes, in areas associated with Mount Arkanu and Mount Awaynat.
Research on rock art in the Jebel Uweinat region indicates the presence of numerous representations associated with the cattle herding period.
In a study on the subject, researcher András Zboray noted that paintings linked to this period are among the most frequent in some sectors of the Uweinat massif.
In the specific case of Arkanu, academic references cited in surveys of the region mention the discovery of sites with rock engravings during an expedition carried out in 2003.
These records include representations of animals, but the dating of each image depends on specific analyses and was not definitively presented in the consulted sources.
Terrain served as shelter for herds
Historical accounts also associate these massifs with pastoral use.
According to Live Science, early 20th-century explorers recorded that Bedouin groups took herds to internal areas of these formations, where the animals could remain for weeks or months.
The text also states that natural entrances could be blocked to prevent cattle from straying.
The relationship between terrain, shade, vegetation, and occasional water helps explain this use.
In a region with very low annual rainfall, the existence of a massif with protected areas and some vegetation cover creates possible points of permanence for animals and people on the move.
In geological terms, Mount Arkanu records the action of magma that rose within the crust and formed a complex of rings.
In environmental terms, it shows how small differences in terrain and rainfall can create areas of vegetation in a hyper-arid landscape.
In archaeological terms, it preserves evidence of human circulation and practices related to pastoralism.
Orbital image brings together geology, climate, and history
The image obtained from the International Space Station allows these elements to be observed in a single scene.
The record combines the circular shapes of the massif, the dry channels carved by occasional water, the surrounding dunes, and the spots where vegetation appears more concentrated.
Even without an artificial origin, Mount Arkanu presents a shape that can resemble a planned construction when viewed from above.
The scientific explanation, however, points to natural processes: **successive magmatic intrusions, prolonged erosion, local rainfall variations, and vegetation adaptation to desert conditions**.
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