A gigantic cloud of dust that originated in China's western deserts made its way around the world in 13 days, a new study reports.
Japanese researchers, writing in the scientific journal Nature Geoscience, used NASA satellite data to track the massive cloud, which formed in early May of 2007.
The cloud was so durable that it passed over the Pacific Ocean twice, finally coming apart and dropping down to the surface the second time.
"The most important achievement is that we tracked this through one full circuit round the globe. Nobody has done this before," Itsushi Uno of Kyushu University's Research Institute for Applied Mechanics told Reuters. "After half a circuit, usually the dust concentration gets very low and you can't track it."
The cloud was about two miles thick and 1,500 miles across. During its travels, it hovered at about 6 miles above the Earth's surface, where the atmosphere is very stable.