A couple sunbath on the beach in Ostrowo, northern Poland, July 20, 2015. Picture taken July 20, 2015. (Photo by Kacper Pempel/Reuters)

A partial solar eclipse is seen in a break in the clouds during rush hour in downtown Wichita Kan., Thursday, October 23, 2014. A partial eclipse occurs when the moon covers a portion of the sun as seen from the Earth. (AP Photo/The Wichita Eagle, Travis Heying)

A paramilitary police officer (right) turns around as hostesses line up for roll call ahead of the Beijing International Automotive Exhibition in Beijing, China, on Monday, April 25, 2016. Tesla Motors Inc. and BYD Co. are among manufacturers showing 147 new-energy vehicles at this year's show. (Photo by Qilai Shen/Bloomberg)

In this July 12, 2007 file photo, a two-day-old piping plover runs along a beach in the Quonochontaug Conservation Area in Westerly, R.I. (Photo by Steven Senne/AP Photo)

Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)

A herder stops for reindeers to have a rest while riding along the tundra area in Nenets Autonomous District, Russia, November 27, 2016. In Russia's remote Arctic regions reindeer herding has been a way of life for centuries. Each winter herders in Russia's sparsely populated Nenets Autonomous District corral their reindeers into open-air pens before selecting weak animals to be culled... (Photo by Sergei Karpukhin/Reuters)

Rachel Hollon of Los Angeles was body painted as Harley Quinn at Comic-Con International in San Diego, USA on Jule 20, 2017. (Photo by K.C. Alfred/San Diego Union-Tribune via ZUMA Press/Rex Features/Shutterstock)

People look at a Christmas tree decorated with colourful lights at a residential compound in Beijing on December 8, 2017. (Photo by Nicolas Asfouri/AFP Photo)