A sand sculpture created by wind

A sculpture created by nature exists in a hostile environment where people rarely visit.

The top image is a crescent-shaped dune in the Rub' al-khali, the southern eastern part of Arabian Peninsula. The bottom image is a star-shaped dune in the Grand Erg Oriental, the eastern part of Algeria, North Africa.

The images above are Bird's-eye view from ASTER ortho data. The heights of the images are increased by approximately 150%.

The crescent-shaped dune, called barchan, is created by unidirectional wind on the sand. The wind blows from the right to the left toward the concaved part in the image. The blue color in the image represents very saline and relatively flat areas called Sabkha. The size of the crescents is as long as 2 - 5 km.

The star-shaped dune has a radial symmetry form.
This shape is formed by wind from random directions which make sand vertically move rather than laterally.
The diameter of the star-shaped dune is 2 - 3 km.

Around the area, successive scenes of these types of dune are captured by ASTER.
This is the art extending several hundred kilometers which can be seen almost nobody.