Over 30 Douglas C-47 Skytrains (Dakotas) making final preparations for flight formation practice before the 75th D-Day Anniversary flight to Normandy in Duxford, England on June 4, 2019. (Photo by UK Air Force Images)

Afghan police officers secure a transportation headquarters that was besieged for two days last weekend, on May 14, 2011 in Kandahar, Afghanistan. Taliban gunmen and suicide bombers unleashed a major assault May 7, 2011 on locations in Kandahar that included the governor's compound, the mayor's office, police stations, and an intelligence agency headquarters. (Photo by Majid Saeedi/Getty Images)

Dog puppy “Sandy” protects against the rain with an umbrella fixed on her leash during a stroll in Rust, southern Germany, on May 26, 2013. (Photo by Patrick Seeger/AFP Photo)

Chihuahua Cooper Babb is dressed in a costume at the 7th annual Running of the Chihuahuas event on May 3, 2014, at the First Tennessee Pavilion in Chattanooga, Tenn. (Photo by Doug Strickland/AP Photo/Chattanooga Times Free Press)

Participants cross cold and muddy waters during the Strong Race competition near Tukums May 4, 2014. About 6500 people competed in this extreme running race, which includes cross-country running, elements of agility and power discipline. (Photo by Ints Kalnins/Reuters)

Actress Frederique Bel attends the Opening ceremony and the “Grace of Monaco” Premiere during the 67th Annual Cannes Film Festival on May 14, 2014 in Cannes, France. (Photo by Pascal Le Segretain/Getty Images)

Backdropped by a night time view of the Earth and the starry sky, the Space Shuttle Endeavour is seen docked to the International Space Station on May 28, 2011. (Photo by Reuters/NASA)

A woman uses her smartphone before the Chanel Cruise Collection 2015/16 fashion show at the Dongdaemun Design Plaza in Seoul, May 4, 2015. (Photo by Thomas Peter/Reuters)