Stefan Dobrovolny of Austria and Inigo Munoz Elorza of Spain (R) stand in front of a quad bike during a simulated Mars mission on Tyrolean glaciers in Kaunertal, Austria, August 7, 2015. The Austrian Space Forum is sending some of its researchers to practice weight-less walking in spacesuits on a glacier which resembles the terrain on Mars. (Photo by Dominic Ebenbichler/Reuters)

The shortlist for the coveted Bird Photographer of the Year awards has been announced by Nature Photographers and the British Trust for Ornithology. Here: Red-billed oxpecker on an impala, Kruger National Park, South Africa. (Photo by Edmund Aylmer/BPOTY/Cover Images/The Guardian)

Paramedics care for a woman who is ill after the Geelong Cup on Geelong Cup day at Geelong Racecourse in Melbourne, Australia, 19 October 2016. The Geelong Racing Club was founded in March 1865 at a public meeting at the British Hotel. The first Geelong Cup was held in 1872 over a distance of two miles. (Photo by Tracey Nearmy/EPA)

Fishermen pull a net containing fish from a pond during the traditional carp haul near the village of Belcice, Czech Republic, October 25, 2016. Carp, the traditional Czech Christmas Eve dinner, is harvested primarly from the region of southern Bohemian lakes. (Photo by David W. Cerny/Reuters)

(L-R) Playmates Summer Altice, Monica Sims and Heather Rae Young attend the Playboy party with TAO at Spire Nightclub on February 4, 2017 in Houston, Texas. (Photo by Christopher Polk/Getty Images for Playboy)

Wild weather drenches tourists, Sydney, Australia on March 7, 2017. A series of photographs as tourists take a soaking on Sydney's iconic Manly Ferry sailing big swells near Sydney's North Head. The Weather Bureau warns of large and powerful surf conditions expected to be hazardous for coastal activities such as rock fishing, swimming and surfing. (Photo by Hugh Peterswald/Pacific Press via ZUMA Wire/Rex Features/Shutterstock)

Competitors pose backstage during the Arnold Classic South America bodybuilding event in Sao Paulo, Brazil, April 22, 2017. (Photo by Nacho Doce/Reuters)