A polar bear family near the Hudson Bay in Churchill, Manitoba, Canada (© Marco Pozzi Photographer/Getty Images)

Tourists walk on pathways through a flowerbed design known as ‘The Australian Billabong’ at the Floriade flower festival in Canberra (© REUTERS/TimWimborne)

Adélie penguins at Possession Island, Antarctica (© Tui De Roy/Minden Pictures)

Séquence de photos de Jupiter (© Image améliorée par Gerald Eichstädt et Sean Doran, CC BY-NC-SA, basée sur les images fournies par la NASA/JPL-Caltech/SwRI/MSSS)

Tintern Abbey, Wales (© Lynda Morris Photography/Getty Images)

Aerial view of Marlborough Sounds, New Zealand (© Mathias Ortmann/Getty Images)

Cleveland Clinic Lou Ruvo Centre for Brain Health in Las Vegas, Nevada (© Garry Belinsky/Offset)

Octopus spotted during a night dive near Kona, Hawaii (© Jeff Milisen/Alamy)

Letchworth State Park, New York (© Jay O'Brien/Danita Delimont)

Bubble Nebula (NGC 7635) (© NASA, ESA, and the Hubble Heritage Team STScI/AURA)

Die illuminierte Alte Bibliothek am Bebelplatz während des Festival of Lights 2018 in Berlin, Deutschland (© FELIPE TRUEBA/EPA-EFE/Shutterstock)

Boats massing for the Barcolana Regatta in the Gulf of Trieste, Italy (© Ababsolutum/E+/Getty Images)

Close-up of a dragonfly wing (© Azwar Thaufeeq/500px/Getty Images)

Lever de Soleil sur Alberta, Canada (© Ambre Haller/Moment/Getty Images)

｢ダイナソー・トラックス｣米国アリゾナ州, チューバシティ (© wanderluster/Getty Images)

Highbush blueberry plants in Acadia National Park, Maine (© Danita Delimont/Gallo Images/Getty Images Plus)

Herbstlaub und Goldfische in einem Teich in Tokio, Japan (© qrsk/Moment/Getty Images)

Chimney Rock and Uncompahgre National Forest, Colorado (© Cory Marshall/Tandem Stills + Motion)

Aerial view of a pumpkin patch in Half Moon Bay, California (© Tinker Street/Michael O'Neal/Gallery Stock)

Pale-throated sloth perched in a tree on Sloth Island, Essequibo River, Guyana (© Suzi Eszterhas/Minden Pictures)

Ashdown Forest, Misty Sunrise, East Sussex, United Kingdom (© Tim Stocker Photography/Getty Images)

Blackbird eating a crab apple in a garden in Wiltshire, United Kingdom (© Nick Upton/Minden Pictures)

'April Pine: Shifting Horizons' at Sculpture by the Sea, Bondi, 2018 (© katacarix/Shutterstock)

Ring-tailed lemurs in Madagascar for World Lemur Day (© Image Source/Alamy)

Das Kunstprojekt „For Forest. Die ungebrochene Anziehungskraft der Natur“ von Klaus Littmann im Wörthersee Stadion, Klagenfurt, Österreich (© UNIMO)

Devotees light oil lamps on the banks of the Sarayu River in Ayodhya, India (© Rajesh Kumar Singh/AP Photo)

Fort Rock Valley Historical Homestead Museum, Oregon (© Prisma by Dukas Presseagentur GmbH/Alamy)

Straw-coloured fruit bats in Kasanka National Park, Zambia (© Nick Garbutt/Minden Pictures)

Charles Bridge over the Vltava River in Prague (© Martin Moxter/Offset)

Corvin Castle, Romania (© DCPmedia/Shutterstock)

Spring in Uluru-Kata Tjuta National Park, Australia (© Sabine Leuenberger/Alamy Stock Photo)