North Korean children wave to people on a Chinese tourist boat on the banks of Yalu River near the Chongsong county of North Korea, opposite the Chinese border city of Dandong, May 8, 2011. (Photo by Jacky Chen/Reuters)

Yalena Leuliette, 7, of Greenbelt, Md., throws seeds from a cattail plant up in the air as she plays while visiting the Kenilworth Aquatic Gardens in northeast Washington, on Sunday, August 9, 2015. Leuliette visits the public garden with her parents a few times a year. (Photo by Jacquelyn Martin/AP Photo)

“The Curiosity Mars rover has imaged a small metallic-looking protuberance on a rock. Visible (in the image below the green lines point to it), the protuberance appears to have a high albedo and even projects a shadow on the rock below...”

A group of 1000 customers receive a facial massage at a sports centre in Jinan, Shandong province, China, May 4, 2015. A group of 1000 women were given a 30 minutes facial beauty treatment together on Monday that achieved a Guinness record for the largest group of people having beauty treatment in the same location, according to local media. (Photo by Reuters/Stringer)

Local villagers fall onto the ground from an ox-cart as they ride to rid evil spirits from their village at Pring Ka-ek village, Cambodi. (Photo by Heng Sinith/AP Photo)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

A man carries an injured girl after what activists said were five air strikes by forces loyal to Syria's President Bashar al-Assad in Douma, eastern al-Ghouta, near Damascus September 11, 2014. (Photo by Bassam Khabieh/Reuters)

A Pakistani scavenger girl writes on a notebook she collected from a garbage, while another girl sits next to her in Lahore, Pakistan, Wednesday, April 1, 2015. Thousands of children pick recyclable items from waste dumping points to earn living for their poor families. (Photo by K. M. Chaudary/AP Photo)