A koala sleeping in a eucalyptus tree, Australia (© Anton Rogozin/Getty Images)

Sunset colours over the icy Wheaton River, Yukon, Canada (© Robert Postma/All Canada Photos/Alamy Stock Photo)

Modica, Sicily, Italy (© Sandro Bisaro/Getty Images)

Leopard in a tree, Kruger National Park, South Africa (© Tonino De Marco/Minden Pictures)

Arenal Volcano seen from Monteverde, Costa Rica (© Lukas Bischoff/Getty Images)

Traffic circle and highway in Bangkok, Thailand (© Avigator Fortuner/Shutterstock)

Wahclella Falls in the Columbia River Gorge, Oregon (© Eric Vogt/Tandem Stills + Motion)

Roques de Benet, Els Ports Natural Park, Catalonia, Spain (© Sergi Boixader/Alamy)

Tate Modern lit up on International Women's Day, London, England (© Stephen Chung/Alamy Stock Photo)

Bisti/De-Na-Zin Wilderness Area, New Mexico (© Ian Shive/Tandem Stills + Motion)

San Jacinto Building's mechanical clock, Beaumont, Texas (© Richard T. Nowitz/Getty Images)

Bryce Canyon National Park, Utah (© Jim Patterson/Tandem Stills + Motion)

Lesser flamingos flying over Lake Magadi, Kenya (© Vicki Jauron, Babylon and Beyond Photography/Getty Images)

Wat Phra Ngam, Ayutthaya Historical Park, Thailand (© boonchai wedmakawand/Alamy)

Colourful tulip fields in Fraser Valley, Abbotsford, BC, Canada (© LeonU/Getty Images)

Giant panda eating bamboo, Chengdu, China (© Suzi Eszterhas/Minden Pictures)

St. Finian's Bay, County Kerry, Ireland (© Atlantide Phototravel/Getty Images)

Elephant Rock, Al-Ula, Saudi Arabia (© Lubo Ivanko/Shutterstock)

Tree frog on leaf (© Tetsuya Tanooka/DEEPOL by plainpicture)

Cave Dale and Peveril Castle in Castleton, Peak District National Park, Derbyshire, England (© James Osmond/Alamy)

Bwindi Impenetrable National Forest, Uganda (© Art Wolfe/DanitaDelimont.com)

Blue Spring, Te Waihou Walkway, New Zealand (© Ian Beattie/Alamy)

Large anvil clouds above the Amazon in Brazil (© NASA)

Silvereyes on a cherry blossom branch, South Korea (© TigerSeo/Getty Images)

Celebrating Holi in Mathura, Uttar Pradesh, India (© Avishek Das/SOPA Images/LightRocket via Getty Images)

Seawater cascades over an ancient coral reef, Hang Rai, Vietnam (© Thang Tat Nguyen/Getty Images)

Teatro Colón in Buenos Aires, Argentina (© Wei Hao Ho/Alamy)

Cherry blossoms in Shanghai, China (© Yaorusheng/Getty Images)

South Stack Lighthouse at sunset, Holyhead, Wales, UK (© mariotlr/Getty Images)

Brown-throated three-toed sloth sleeping in cecropia tree, Costa Rica (© Juan Carlos Vindas/Getty Images)

Easter eggs painted by Tünde Csuhaj, Szekszárd, Hungary (© ATTILA KISBENEDEK/AFP/Getty Images)