Andrea Petkovic of Germany in action against Sara Errani of Italy during day one of the Mutua Madrid Open tennis tournament at the Caja Magica on May 3, 2014 in Madrid, Spain. (Photo by Julian Finney/Getty Images)

“Winter Climbing from inside Ben Nevis”. The view from inside the mountain, as a winter climber passes through the cave on Minus Three gully. Photo location: Ben Nevis, Fort William, Scotland. (Photo and caption by Daniel Wildey/National Geographic Photo Contest)

A frog sits on a leaf and instead of seeing a reflection of itself in the water below, it sees a snail, attached to the bottom of the leaf, in a fish tank in Vietnam. (Photo by Duong Quoc Dinh/Solent Ne/SIPA Press)

A man and a dog bathe in a fountain during celebrations of Paratroopers' Day in Moscow' s Gorky Park on August 2, 2017. Russia' s Airborne Troops (Blue Berets) celebrate their professional holiday on the Day of Elijah the Prophet, their Patron. (Photo by Stanislav Krasilnikov/TASS)

A mother bear takes a dip in the water to cool off in the warm summer sun but refuses to leave her three youngsters behind – so they climb aboard her back. (Photo by Jon Langeland/Solent News & Photo Agency)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)

A man carries his dog as he prays during Vesak Day, an annual celebration of Buddha's birth, enlightenment and death, at Wat Yai Chai Mongkhon temple in Ayutthaya, Thailand, May 10, 2017. (Photo by Athit Perawongmetha/Reuters)

Iraqi children play with a ball on a street blocked with burning tyres, amid a general strike in the southern city of Basra, on November 25, 2019. The demonstrations rocking the capital and Shiite-majority south since October 1 are the biggest grassroots movement the country has seen in decades. Sparked by outrage over rampant government corruption, poor services and lack of jobs, they have since gone straight to the source: calling out the ruling system as inherently flawed and in need of a total overhaul. (Photo by Hussein Faleh/AFP Photo)