A pilot looks up from a U.S. F-22 Raptor fighter as it prepares to refuel in mid-air with a KC-135 refuelling plane over European airspace during a flight to Britain from Mihail Kogalniceanu air base in Romania April 25, 2016. (Photo by Toby Melville/Reuters)

St. Vincent performs at the Coachella Valley Music and Arts Festival in Indio, California, U.S., April 13, 201. (Photo by Mario Anzuoni/Reuters)

This picture taken on May 31, 2018 shows a villager walking between abandoned houses covered with overgrown vegetation in Houtouwan on Shengshan island, China' s eastern Zhejiang province. Houtouwan was a thriving fishing community of sturdy brick homes that climb up the steeply hilled island of Shenghshan, but is now abandoned, with entire houses completely overgrown as if vacuum- sealed in a lush layer of green. (Photo by Johannes Eisele/AFP Photo)

A bull hits a reveller during the first running of the bulls of the San Fermin festival in Pamplona, Spain, July 7, 2018. Each day at 8am hundreds of people race with six bulls, charging along a winding, 848.6-metre (more than half a mile) course through narrow streets to the city's bull ring, where the animals are killed in a bullfight or corrida, during this festival dating back to medieval times and also featuring religious processions, folk dancing, concerts and round-the-clock drinking. (Photo by Vincent West/Reuters)

This undated photo provided by NOAA in May 2018 shows aurora australis near the South Pole Atmospheric Research Observatory in Antarctica. When a hole in the ozone formed over Antarctica, countries around the world in 1987 agreed to phase out several types of ozone-depleting chemicals called chlorofluorocarbons (CFCs). Production was banned, emissions fell and the hole shriveled. But according to a study released on Wednesday, May 16, 2018, scientists say since 2013, there’s more of a banned CFC going into the atmosphere. (Photo by Patrick Cullis/NOAA via AP Photo)

North Korean bodyguards run along a limousine transporting Kim Jong Un upon his arrival in Dong Dang, Vietnam, February 26, 2019. The second meeting of the US President and the North Korean leader, running from 27 to 28 February 2019, focuses on furthering steps towards achieving peace and complete denuclearization of the Korean peninsula. (Photo by Reuters/Stringer)

Paolo Guerrero of Brazil's Internacional reacts after missing an opportunity to score during a Copa Libertadores soccer match against Chile's Palestino in Porto Alegre, Brazil, Tuesday, April 9, 2019. (Photo by Diego Vara/Reuters)

People take photos with the skyline of the central business district in Singapore on September 10, 2015. (Photo by Edgar Su/Reuters)