The world-famous sprinter Usain Bolt, 30, took a break from the track to celebrate Carnival as revellers doused each other with paint in Trinidad and Tobago on February 26, 2017. (Photo by David Wears/Splash News and Pictures)

Tour guides wearing traditional Chinese dress practice smiling by biting chopsticks at Qingming Grand-River Park in Kaifeng, central China's Henan Province on March 2, 2017, aiming to provide better service for visitors. (Photo by IPA Asia via ZUMA Wire)

Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

An AH-64D Apache attack helicopter flies in front of a wall of fire during the South Carolina National Guard Air and Ground Expo at McEntire Joint National Guard Base, South Carolina, U.S. on May 6, 2017. (Photo by Jorge Intriago/Reuters/Courtesy Air National Guard)

A person poses on the track during a fashion competition at the Durban July horse racing event in Durban, South Africa July 1, 2017. (Photo by Rogan Ward/Reuters)

Gigi Hadid and Emily Ratajkowski celebrated the opening of the shopping centre by taking part in the evening's ribbon cutting ceremony in Mykonos, Greece on June 30, 2018. (Photo by Richard Young/Rex Features/Shutterstock)

In this Thursday, March 28, 2019, photo, a “golden giant burger” is served at a restaurant of Hotel Grand Hyatt Tokyo in Tokyo. The $900 wagyu (Japanese-produced beef) burger was unveiled to commemorate the era change. What’s in a name? Quite a lot if you’re a Japanese citizen awaiting the official announcement Monday, April 1, 2019 of what the soon-to-be-installed new emperor’s next era will be called. It’s a proclamation that has happened only twice in nearly a century, and the new name will follow Emperor Naruhito, after his May 1 investiture, for the duration of his rule, attaching itself to much of what happens in Japan. (Photo by Kyodo News via AP Photo)

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)