Sand Dunes from ASTER
November 24, 2000
The above image was taken from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite - part of NASA's Earth Observation System. ASTER has a resolution of 15 m (46.5 ft) in the visible bands, which is the highest resolution (greatest detail available) of any of Terra's observing instruments. This image was acquired on June 25, 2000 and covers an area of 37 by 28 km. The image shows a series of northeast to southwest trending linear sand dunes in the Rub' al Khali, or the Empty Quarter in Saudi Arabia. These transverse sand dunes are typically oriented perpendicular to the prevailing wind and may be 32 m (100 feet) in heigth. The dunes have a yellowish hue due to the presence of iron oxide minerals. The inter-dune area is made up of clays and silt and appears bluish because of their high reflectance in the blue part of the electromagnetic spectrum. The Rub' al Khali is the world's largest continuous sand desert, stretching across about 650,000 square kilometers (250,966 square miles) in southern Saudi Arabia, Yeman, Oman, and the United Arab Emirates.