A solar-powered plane takes off from Jiangbei International Airport in southwest China's Chongqing Municipality, Tuesday, April 21, 2015. The Solar Impulse 2 departed Chongqing on Tuesday for a 1190-kilometer (642-mile) flight to the city of Nanjing in eastern China, the sixth leg of its around-the-world flight. (Photo by Chinatopix via AP Photo)

Carrying a portable shrine on their shoulders, participants all clad in traditional happi coats, parade through precincts of the Kanda Myojin shrine during the annual summer festival in Tokyo, Saturday, May 9, 2015. (Photo by Eugene Hoshiko/AP Photo)

A woman stands in a gift shop in central Rason city, part of the special economic zone northeast of Pyongyang, in this August 30, 2011 file photo. North Korea is a militarized, male-dominated society, but it is women who are making the money as the insular nation allows an unofficial market-based economy to take shape. (Photo by Carlos Barria/Reuters)

Tianmen Mountain is a mountain located within Tianmen Mountain National Park, Zhangjiajie, in northwestern Hunan Province, China.

In this aerial file photo taken on Tuesday, October 31, 2017, a woman walks past a statue of Soviet Union founder Vladimir Lenin at the Russian leased Baikonur cosmodrome, in Kazakhstan. The thousands of statues of Vladimir Lenin spread across the vast region bring to mind poet Vladimir Mayakovsky's ringing line of devotion: “Lenin lived, Lenin lives, Lenin will live”. (Photo by Dmitri Lovetsky/AP Photo)

A duck swims in a Osterbekkanal during a the rainy autumn afternoon, central Hamburg, Germany 20 November 2017. (Photo by Srdjan Suki/EPA/EFE)

An Atlantic seal pup lies amongst the rocks at St Martin's Haven, Pembrokeshire, Wales, Britain October 8, 2018. Seal pups are born with fluffy white non-waterproof coats which they moult out in their fourth week. (Photo by Rebecca Naden/Reuters)

A picture taken with a drone shows the giant landart painting entitled “Message From Future” by French artist Saype in the park “La Perle du Lac” in Geneva, Switzerland, 16 September 2018 (issued 17 September). The artwork covering 5,000 square meters was produced with biodegradable paints made from natural pigments. The artist called the little girl “Future” as a symbol of the generations from the future and the small origami boats that she drops into Lake Geneva aims to represent a message of hope sent to the world. (Photo by Valentin Flauraud/EPA/EFE)