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

Women's March in Victoria, B.C. Jan. 21, 2017 (© Mick Ritzel/Alamy Stock Photo)

The Trossachs National Park in autumn, Stirling, Scotland (© Jon Arnold/Danita Delimont)

Sequenz farbkorrigierter Bilder des Jupiter (© Nachbearbeitetes Foto von Gerald Eichstädt und Sean Doran, CC BY-NC-SA, basierend auf Bildern mit freundlicher Genehmigung von NASA/JPL-Caltech/SwRI/MSSS)

Sequence of enhanced-colour images of Jupiter (© Enhanced Image by Gerald Eichstädt and Sean Doran, CC BY-NC-SA, based on images provided Courtesy of NASA/JPL-Caltech/SwRI/MSSS)

"Garden Tower" at Nuit Blanche in Toronto, Oct. 5, 2013 (© Lucas Oleniuk/Toronto Star via Getty Images)

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

Cleveland Clinic Lou Ruvo Center 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)

Arches National Park, Moab, Utah (© Whit Richardson/Alamy Stock Photo)

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

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

蜻蜓翅膀特写 (© Azwar Thaufeeq/500px/Getty Images)

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

A fossilized carboniferous fern (© Juan Carlos Munoz/Minden Pictures)

Autumn leaves and goldfish in Tokyo, 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)

Lily pads and floating autumn coloured leaves, Waterloo, Que. (© Design Pics/Offset)

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

County Bridge in New Hampshire (© Denis Tangney Jr/E+/Getty Images)

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

Klaus Littmann's 'FOR FOREST: The Unending Attraction of Nature' in Wörthersee Stadion, Klagenfurt, Austria (© 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)