Thousands of runners take part in the annual City2Surf road race on August 12, 2018 (© PETER PARKS/AFP/Getty Images)

Reflections on Crummock Water in the Lake District, Cumbria, England (© Damian Harrison/Alamy)

A thunderstorm rolls across the Theodore Roosevelt National Park in North Dakota (© Judith Zimmerman/Danita Delimont)

Swift fox pups in Grasslands National Park near Val Marie in Saskatchewan, Canada (© John E Marriott/age fotostock)

Kayaker exploring sandstone sea caves in Apostle Islands National Lakeshore near Bayfield, Wisconsin (© Chuck Haney/Danita Delimont)

White storks at Los Barruecos Natural Monument, Caceres, Spain (© Wild Wonders of Europe/Widstrand/Minden Pictures)

View from the Great Ocean Road with the Milky Way, Victoria, Australia (© idizimage/iStock/Getty Images Plus)

Male leopard in Linyanti Wildlife Reserve, Botswana (© Karine Aigner/Tandem Stills + Motion)

The Supertree Grove in Singapore's Gardens by the Bay (© John Warburton-Lee/Danita Delimont)

Seville, Spain’s Guadalquivir River and Triana Bridge for the 500th anniversary of Magellan’s departure (© Zu Sanchez Photography/Getty Images)

Elephants in the Amboseli National Park, Kenya (© Adam Bannister/Offset)

Mars Express image of the icy cap at Mars’ south pole (© ESA/DLR/FU Berlin/Bill Dunford)

Male and female Ecuadorian horned anoles in Mindo, Ecuador (© James Christensen/Minden Pictures)

Smögen, Sweden (© Martin Wahlborg/Getty Images Plus)

Yukon River viewed from the Midnight Dome, Dawson City, Yukon, Canada (© Robert Postma/Getty Images)

Bees for National Honey Bee Day (© Angela Parker/Offset)

Tidal pools of Leça da Palmeira, Portugal (© Fernando Guerra/age fotostock)

The interior of the historic Mortlock Library, in the State Library of South Australia, Adelaide (© Ray Warren Creative/Alamy Stock Photo)

Muje-Oulu Lake in eastern Finland (© Topi Ylä-Mononen/plainpicture)

Wildebeest herd crossing the Mara River between Kenya and Tanzania (© zhengvision/Getty Images)

Soft Coral (Ellisella sp) in the Great Barrier Reef, Australia (© Gary Bell/Oceanwide/Minden Pictures)

Farmland in Washington state's Palouse region (© Art Wolfe/Getty Images)

Brown bears in Katmai National Park, Alaska (© imageBROKER/SuperStock)

Satellite image of the Burning Man Festival in Black Rock City, Nevada (© DigitalGlobe/ScapeWare3d/Getty Images)

Royal Albert Hall during the annual BBC Proms festival in London (© Oli Scarff/Getty Images)

Anak Krakatoa volcano erupting off the coast of Sumatra, Indonesia (© Martin Rietze/Alamy)

The Gardens of the Palazzo Corsini al Prato in Florence for the New Generation Festival (© Will Perrett/Alamy)

Hardee County Fair in Wauchula, FL (© Oscar G. Davila/Getty Images)

Asbury Park in New Jersey (© Patrick Morisson/Alamy)

Castelbouc and the Gorges du Tarn along the Tarn River in France (© Stefan Schurr/Westend61/Offset)

Castelbouc and the Gorges du Tarn along the Tarn River in France (© Stefan Schurr/Westend61/Offset)