Photographers gather to take pictures of pilot Andre Borschberg (C) ahead of the take off of Solar Impulse 2-a solar powered plane- in Nanjing, China, May 31, 2015. The world's largest solar-powered airplane, Solar Impulse 2, took off from eastern China's Nanjing on Sunday to continue its round-the-world voyage. The Swiss-made plane left Nanjing's Lukou International Airport at 2:39 in the early morning, with former fighter pilot Borschberg at the controls alone for the entire 8,200-kilometer flight from Nanjing to Hawaii, the toughest leg of its marathon adventure. (Photo by Reuters/Solar Impulse)

Farmers work on a farm near a construction site of new residential buildings in Shanghai, China, February 20, 2016. (Photo by Aly Song/Reuters)

A participant jumps during the Red Bull Jump and Freeze competition at the ski resort of Gudauri, Georgia, March 20, 2016. (Photo by David Mdzinarishvili/Reuters)

A woman walks with a squirrel on her shoulder at Maeklong market at the outskirts of Bangkok, Thailand September 20, 2016. (Photo by Jorge Silva/Reuters)

A flock of starlings flies over Lake Leman on an autumn morning in the Lavaux near Grandvaux, Switzerland October 20, 2016. (Photo by Denis Balibouse/Reuters)

A woman shields her face from the sun as she rides her scooter in Ahmedabad, India May 20, 2016. (Photo by Amit Dave/Reuters)

A woman stands at the door of her shanty at a slum in Mumbai, India July 20, 2016. (Photo by Danish Ismail/Reuters)