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)

Hundreds of Nigerians celebrate at an intersection in the flashpoint northern city of Kaduna on March 31, 2015 the victory of main opposition All Progressives Congress (APC) presidential candidate Mohammadu Buhari. (Photo by Nichole Sobecki/AFP Photo)

In this timed-exposure night photo taken early on February 12, 2017, Mount Sinabung volcano spews reddish smoke and ash, as seen from the Karo district in North Sumatra province. Activity levels have increased in the past week, with Sinabung shooting hot ash clouds into the sky dozens of times, according to the local volcano monitoring agency. (Photo by AFP Photo/Stringer)

A petitioner with her grievances written on her clothes walks along a street in Beijing Tuesday, December 22, 2015. After months behind bars, Pu Zhiqiang, one of China's most prominent human rights lawyers, left a detention center Tuesday after receiving a suspended prison sentence in a case involving online comments critical of the ruling Communist Party. (Photo by Ng Han Guan/AP Photo)

A general view of atmosphere at the annual VOLT Festival in Sopron, 208 kms west of Budapest, Hungary on August 16, 2016. (Photo by Mudra László/Rockstar Photographers)

An Indian toddler plays amid marigold flowers at a wasted flowers dumping site, besides a flower market in Mumbai, India, 28 September 2016. Marigold flowers are used in many religious ceremonies in the temples in India. Strung together they make colourful garlands and are used as an offering in temples and to decorate them. (Photo by Divyakant Solanki/EPA)

in Qayyarah, about 31 miles (50 km) south of Mosul, Iraq, Sunday, October 23, 2016.in Qayyarah, some 50 kilometers south of Mosul, Iraq, Sunday, Oct. 23, 2016. Islamic State fighters torched a sulfur plant south of Mosul, sending a cloud of toxic fumes into the air that mingled with oil wells the militants had lit on fire to create a smoke screen. (Photo by Marko Drobnjakovic/AP Photo)

The Sugar Plum Fairy, Katherine Free, left, dances with the dog, Pig, during the Birmingham's Ballet “Mutt-cracker”, a rendition of the famous ballet “The Nutcracker”, in Birmingham, Alabama, December 8, 2016. (Photo by Brynn Anderson/AP Photo)