Star dunes are sand formations with at least three ridges radiating from a central peak. Their unusual shape is the result of constant changes in wind directions. (Image credit: NASA/ISS Program)
This stunning photo taken by an astronaut shows about a dozen large “star dunes” slowly swaying on a sandy plateau near the edge of the Sahara Desert. The rare dunes, often mistaken for man-made pyramids, may have been around for centuries, new research suggests.
The unique formations are found in Erg Chebbi. This field of open, windswept sand, or erg, covers about 65 square miles (170 square kilometers) in southwestern Morocco along the northwestern edge of the Sahara. The erg is surrounded by plains but contains some of the tallest dunes in the Sahara, making it look like a mountain range when viewed from afar.
The village of Merzouga is also visible in the lower right corner of the image. It is built on a large aquifer, allowing palm groves to flourish alongside the desert landscape and attracting tourists eager to explore the sandy peaks of the erg.
A star dune is a type of sand dune with at least three ridges radiating from a central peak, giving it a star-shaped appearance when viewed from above, according to NASA Earth Observatory. However, when viewed from the side, their many smooth slopes, known as “slip faces,” can make star dunes look very pyramid-like from ground level.
These dunes, which can exceed 300 feet (90 meters) in height, form only in places where the wind direction constantly changes, allowing them to form different slopes, according to the National Park Service. As a result, they move only a few inches each year in the direction of the strongest prevailing wind. That's significantly slower than some other drifting dunes, which can move up to 1,000 feet (300 m) a year if the wind blows in one direction.
At ground level, the star dunes at Erg Chebbi can look like man-made pyramids when viewed from a distance.
The tallest star dune in Erg Chebbi, Lala Lallia, reaches 330 feet (100 m) and is located just north (left) of the dunes in the satellite image. In March 2024, researchers found that this dune is about 900 years old, significantly younger than previous estimates.
Sourse: www.livescience.com
