This photo, an edited version of the astronaut photograph taken by the crew of ISS Expedition 27 on 16 May 2011, depicts the south-eastern edge of the Ar Rub’ al Khali desert in the Sultanate of Oman.
The Ar Rub’ al Khali (or the Empty Quarter), covers an area of 650,000 square kilometers (250,000 sq miles) approximately, with its maximum length and width extending up to 1,000 kilometers (620 miles) and 500 kilometers (310 miles) respectively.
It is the largest continuous spread of sand desert on Earth, covering most of the south-central portion, or about one-third, of the Arabian Peninsula. The desert encompasses most of Saudi Arabia and some areas of the United Arab Emirates, the Sultanate of Oman and Yemen.
In the middle portions of the desert there are plateau-like raised areas hardened by deposits of calcium carbonate, gypsum and marl formed from lakes that once existed here during different periods from 5,000 to 37,000 years ago. The color of the sand is reddish orange or reddish brown due to the presence of feldspars.
As various fossil remains recovered from the region indicate, the lakes and the surrounding areas were once home to several species of plants and other living beings including trees, shrubs, algae, hippopotamuses, water buffalos, long-horned cattle, snails, ostracods (seed shrimps), freshwater clams (mollusks). The discovery of chipped flint tools and other crude implements used by the early man indicate that there were human settlements in the region.
Now the Empty Quarter is estimated to contain the second largest oil deposit in the world, after vast oil reserves were discovered underneath the sand dunes. The Ghawar Oil Field, the largest oil field in the world and Shaybah, a major crude oil producing site, both in Saudi Arabia, are located in this desert.
The photos taken by the astronauts and cosmonauts of International Space Station Programs being of immense value to scientists and the public, they are made freely available on the Internet. You can view more photos and download them for use in your websites or blogs, or for use as screensavers and wallpapers (with instructions on how to create them), at NASA – Gateway to Astronaut Photography of Earth.