Riot police runs as a woman falls down during a May Day rally in the Kreuzberg district of Berlin, Germany, 01 May 2016. (Photo by Kay Nietfeld/EPA)

Spectators pass through security screening ahead of the New Year's Eve celebration in Times Square in New York, on Sunday, December 31, 2017. (Photo by Peter Morgan/AP Photo)

In this Friday, March 13, 2015, Mitch Seavey's lead dogs with frosty whiskers at the Huslia, Alaska, checkpoint for the Iditarod Trail Sled Dog Race. (Photo by Loren Holmes/AP Photo/Alaska Dispatch News)

Ultra- trailers compete at sunrise on September 2, 2017 in Courmayeur, Italy, during the 15 th edition of the Mount Blanc Ultra Trail (UTMB), a 170 km race around the Mont Blanc crossing France, Italy and Switzerland. The 15 th Ultra- Trail du Mont- Blanc (UTMB) is a mountain ultramarathon with numerous passages in high altitude (>2500 m) and in difficult weather conditions (night, wind, cold, rain or snow). (Photo by Jeff Pachoud/AFP Photo)

These images show a heart-warming moment between a loving couple as they’re lit up under a stunning starry night sky. Taken on the Crimean Peninsula, the images show couples posed up beneath a glorious midnight skyscape. (Photo by Andrei Sheliakin/Caters News Agency)

These stunning images show a group of aerial artists lighting up the night sky. Taken by photographer Casey Grimley, 37, the photos show pole dancers and aerial artists at various locations in Southern California, including the famed Joshua Tree National Park. (Photo by Casey Grimley/Caters News Agency)

Photographer Maurizio Pignotti, 46, spends all night in freezing temperatures painstakingly shooting the breathtaking crystal-clear stars. He uses a technique where he merges together anywhere between 80 and 450 shots to create what he describes as a “rainbow of stars”. Space-lover Maurizio, captures the star trails on the borders of the Adriatic Sea – including the Sibillini Mountains National Park, the Conero National Park, and the Gargano National Park. (Photo by Maurizio Pignotti/Caters News)

A life-size robot named “Mark 1”, built by product and graphic designer Ricky Ma, 42, is seen in Hong Kong, China March 31, 2016. Ma, a robot enthusiast, spent a year-and-a half and more than HK$400,000 ($51,000) to create the humanoid robot, which is modelled after a Hollywood star, to fulfil his childhood dream. The eyes of the robot include face and color tracking functions. (Photo by Bobby Yip/Reuters)