The orange sand dunes of the eastern Ar Rub’ al Khali Desert (empty quarter) are pictured in this spectacular, high-oblique, north-looking photograph. More than 300 miles (500 kilometers) wide and nearly 700 miles (1100 kilometers) long, this hot, arid desert dominates the landscape of the southeastern Arabian Peninsula. The absence of rainfall and the scarcity of vegetation make this area uninhabitable, even by pastoral nomads. Bedouin tribesmen, who live around the fringes of this great desert, dare not enter the region during the summer when temperatures soar above 122 degrees Fahrenheit (50 degrees Celsius) during the day and drop below 32 degrees Fahrenheit (0 degrees Celsius) at night. Sand dunes, whose average height is almost 660 feet (200 meters), can rise more than 1000 feet (330 meters). So difficult is this desert for humans to penetrate, much of the region remains unexplored. Visible in the photograph are the coast of Oman, the nearby high plateau that descends in elevation toward the sand dunes (near the center of the photograph), and clouds that cover the central portion of the Persian Gulf (north of the sand dunes near the horizon of the photograph).