A pink elephant balloon, one of the entries in the Canadian Hot Air Balloon Championships, lands in a field in High River September 27, 2013. The event is a qualifier for the World Hot Air Balloon Championships in Sao Paulo in 2014. (Photo by Mike Sturk/Reuters)

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)

In this handout from the Ministry of Defence, Royal Air Force VC10 and Tristar air-to-air refuelling aircraft support the first UK air combat mission in support of UN Resolution 1973 in flight on March 19, 2011. Col Muammar Gaddafi has vowed a “long war” against the “crusader aggression” after over 100 missiles were fired by the US and UK, during multi-national action aimed at enforcing a UN-mandated no-fly zone. (Photo by SAC Neil Chapman/MoD via Getty Images)

Hot air balloons rise over Innes Common Park during a dawn lift on March 29, 2012 in Hamilton, New Zealand. Each Autumn over 30 hot air balloons grace the sky as part of the Balloons Over Waikato Festival. (Photo by Sandra Mu/Getty Images)

Paramilitary policemen take part in a training in Chaohu, Anhui province, China December 28, 2015. (Photo by Reuters/China Daily)

A bus goes through a flooded street in Wuhan, Hubei province, China July 6, 2016. (Photo by Reuters/China Daily)

A competitor walks on tightrope during a performance in Taizhou, Zhejiang Province, China, May 7, 2016. (Photo by Reuters/China Daily)

Girls rest on stairs at the China Digital Entertainment Expo and Conference (ChinaJoy) in Shanghai, China July 27, 2017. (Photo by Aly Song/Reuters)