Sand dunes in Oman
The image, taken by astronauts, is of crescent-shaped sand dunes alternating with salt flats called sabkhas.
The setup, in Oman, has lots of names, according to NASA . It is known as the Ar Rub' al Khali, or the Empty quarter. It's also referred to as a sand sea.
The dunes are oriented at right angles to northwesterly trade winds, called the Shamal winds, that originate in Iraq.
The image was taken May 16, 2011 by astronauts aboard the International Space Station.