Snow-covered deserts are rare, but that is exactly what NASA's Aqua satellite observed as it passed over the Takla Makan Desert in the Xinjian Uygyr autonomous region of western China on 2 January 2013. The Takla Makan is one of the world's largest and hottest sandy deserts. Water flowing into the Tarim Basin has no outlet so, over the years, sediments have steadily accumulated. In parts of the desert, sand can pile up to 300 m (roughly 1,000 ft) high. The mountains that enclose the sea of sand – the Tien Shan in the north and the Kunlun Shan in the south – are also covered with what appears to be a significantly thicker layer of snow. Image courtesy of NASA.