A handout picture provided by Solar Impulse on 18 March 2015 shows the Swiss solar-powered plane Solar Impulse 2, HB-SIB, taking off with Swiss explorer Andre Borshberg on board for the third leg Ahmedabad to Varanasi, of the Round-The-World, in Ahmedabad, India, 18 March 2015. Swiss explorers Bertrand Piccard and Andre Borschberg attempt to circumnavigate the world flying with an aircraft, with a 72 metres wingspan, powered only by solar energy without a drop of fuel. (Photo by EPA/Solar Impulse)

A lady-in-waiting adjusts the dress and Christian Louboutin shoes of Dayangku Raabi'atul 'Adawiyyah Pengiran Haji Bolkiah as Adawiyyah waits for Prince Abdul Malik to arrive for the “bersanding” or enthronement ceremony at their wedding in the Nurul Iman Palace in Bandar Seri Begawan April 12, 2015. Malik is the son of Brunei's Sultan Hassanal Bolkiah, one of the world's richest men. (Photo by Olivia Harris/Reuters)

An aerial view shows the Amazon rainforest at the Bom Futuro National Forest near Rio Pardo in Porto Velho, Rondonia State, Brazil, September 3, 2015. The town of Rio Pardo, a settlement of about 4,000 people in the Amazon rainforest, rises where only jungle stood less than a quarter of a century ago. Loggers first cleared the forest followed by ranchers and farmers, then small merchants and prospectors. Brazil's government has stated a goal of eliminating illegal deforestation, but enforcing the law in remote corners like Rio Pardo is far from easy. (Photo by Nacho Doce/Reuters)

A mother prays for success for her child in the college entrance examinations at a Buddhist temple in Seoul, South Korea, November 12, 2015. About 630,000 students on Thursday sat for the annual exams that could lead them to one of the country's top universities. In South Korea, there is no higher achievement than to be accepted by a prestigious university. As a result, many students prepare for these entrance exams from an early age, often studying up to 16 hours a day for years to take this test. (Photo by Kim Hong-Ji/Reuters)

Members of ASC Tornados, the motorcycle display team of the Indian army, lie in a row on the ground as another performs a stunt by jumping over them during the 225th anniversary celebrations of Army Service Corps in Bangalore, India, Tuesday, December 8, 2015. The Army Service Corps which was established in 1790 is an arm of the Indian Army which handles its logistic support function. (Photo by Aijaz Rahi/AP Photo)

NASA's DHC-3 Otter plane flies in Operation IceBridge-Alaska surveys of mountain glaciers in Alaska in this image released on September 18, 2014. Over the past few decades, average global temperatures have been on the rise, and this warming is happening two to three times faster in the Arctic. (Photo by Chris Larsen/Reuters/NASA/University of Alaska-Fairbanks)

Revellers take part in the the 70th Annual Columbus Day Parade in New York, October 13, 2014. (Photo by Eduardo Munoz/Reuters)

Two Bulgarian tourists pose in front of the Eiffel Tower in Paris on their last day in the capital on March 24, 2014. (Photo by Franck Fife/AFP Photo)