Photographers gather to take pictures of pilot Andre Borschberg (C) ahead of the take off of Solar Impulse 2-a solar powered plane- in Nanjing, China, May 31, 2015. The world's largest solar-powered airplane, Solar Impulse 2, took off from eastern China's Nanjing on Sunday to continue its round-the-world voyage. The Swiss-made plane left Nanjing's Lukou International Airport at 2:39 in the early morning, with former fighter pilot Borschberg at the controls alone for the entire 8,200-kilometer flight from Nanjing to Hawaii, the toughest leg of its marathon adventure. (Photo by Reuters/Solar Impulse)

Farmer Zhang Xianping rides his pig "Big Precious" during an interview with the media, in Zhangjiakou, Hebei province, China, November 2, 2015. Zhang, a pig breeder, instead of killing it, decided to keep the two-year-old "Big Precious" as pet when its weight reached 600 kg, according to local media. (Photo by Reuters/China Daily)

European Space Agency astronaut Tim Peake will return home after a six-month long mission on the International Space Station,on June 18, 2016. Peake was the first British ESA astronaut to visit the ISS and captured hundreds of photographs of the Earth during his mission. Here: “Lots of sun-glint right now during our whole orbit – we haven't seen a sunset for over 3 days”, he wrote. (Photo by Tim Peake/ESA/NASA)

A shooting star (L, top) is seen on the night sky during the perseid meteor shower in Jankowo, near Poznan, 11 August 2016. The first half of August is traditionally the best time to look out for meteors called “shooting stars”, or perseids which are the leftover dust particles of a comet tail associated with comet Swift-Tuttle. (Photo by Lukasz Ogrodowczyk/EPA)

Participants climb a 10km muddy obstacle course during the “Run Mud” race, on March 29, 2019 in the Israeli mediterranean coastal city of Tel Aviv. Over 6,000 participants took part in the obstacle race, with up to 18 artificial obstacles on three tracks (10 km, five km or two km). (Photo by Jack Guez/AFP Photo)

English actress and model Elizabeth Hurley launches Harrods beach and children's wear at the Knightsbridge store in London, England on December 6, 2006. (Photo by Daniel Deme/WENN)

Starting on Monday, August 12, Perseid meteors will streak across the summer sky for a couple of nights, offering casual stargazers and serious nighttime photographers a chance to capture a glimpse of the annual meteor shower. Photo: Photographer David Kingham created this composite image from 23 photos on August 12, 2012. (Photo by David Kingham)

A policeman stands next to supporters of Kenyan President Uhuru Kenyatta lying unconscious after being beaten by police when they tried to storm through gates to get in during Kenyatta's inauguration ceremony at Kasarani stadium in Nairobi, Kenya Tuesday, November 28, 2017. Kenyatta is being sworn in on Tuesday, ending a months-long election drama that saw the first vote nullified by the country's top court and the second boycotted by the opposition. (Photo by Ben Curtis/AP Photo)