Cheetah cubs climbing acacia trees in Ngorongoro Conservation Area, Tanzania (© Paul Souders/Getty Images)

Purple Saxifrage (Saxifraga oppositifolia) in bloom Bathurst Island, Nunavut (© Gerrtt Vyn/Minden Pictures)

Ruins of a kasbah in Kalaat M'Gouna, Morocco (© Leonid Andronov/Getty Images)

Snowy owl at Jones Beach, Long Island, New York (© Vicki Jauron/Getty Images)

Salar de Uyuni, Bolivia (© Ignacio Palacios/Getty Images)

An old lighthouse under the starry sky in Rose Blanche, Nfld. (© Adam Woodworth/Cavan)

Inca fortress of Sacsayhuamán near Cusco, Peru (© Susanne Kremer/eStock Photo)

Bluebonnets growing alongside an old road in the Texas Hill Country (© Inge Johnsson/Alamy)

People looking at the crowded Avenue des Champs-Élysées from the Arc de Triomphe on May 8, 1945, Paris, France (© AFP via Getty Images)

Barn owl sitting on a branch (© blickwinkel/Alamy)

Burchell's zebra mother and foal in Rietvlei Nature Reserve, South Africa (© Richard Du Toit/Minden Pictures)

The Old Patriarch Tree of Grand Teton National Park, Wyoming (© George Sanker/Minden Pictures)

Painted and leaded glass window panel on display at the Florence Nightingale Museum, London, U.K. (© David Gee/Alamy)

Moose snacking on water lilies in Millinocket, Maine (© Scott Suriano/Getty Images)

Rice fields in the Sidemen Valley, with Mount Agung in the background, Bali, Indonesia (© Jon Arnold/Danita Delimont)

Grand Canyon and Colorado River from Toroweap Overlook, Grand Canyon National Park, Arizona (© Matteo Colombo Travel Photo/Shutterstock)

‘Maple Leaf’ tulips In a garden in Ottawa (© Bao Le Dinh Quoc/Alamy Stock Photo)

Fishing village of Henningsvær with Henningsvær Idrettslag Stadion, Nordland, Norway (© Viktor Posnov/Alamy)

National Museum of Qatar in Doha, Qatar (© Hasan Zaidi/Shutterstock)

Roaring Fork in Great Smoky Mountains National Park, Tennessee (© Paul Hassell/Tandem Stills + Motion)

Moss-covered trees and ferns in a rainforest along Nile Creek, near Campbell River, B.C. (© Robert Postma/Plainpicture)

'Strolling the Biltmore,' a painting by Jeff Hanson (© Jeff Hanson Art)

Reichenbach Falls, Bernese Oberland, Switzerland (© Chris Milne/Alamy)

A male yellow-bellied slider (© Marko Markovic Photography/Shutterstock)

Greenan Maze in County Wicklow, Ireland (© Peter Krocka/Shutterstock)

Spring peeper (Hyla crucifer) perched on a black-eyed Susan in a flower garden in Ontario (© Don Johnston/Alamy Stock Photo)

Aerial view of Everglades National Park, Florida (© Tetra Images/Getty Images)

The long plumes of a three-flowered avens as it goes to seed (© Sunshine Haven Photo/Shutterstock)

Aerial view of Marley Beach, Bermuda (© Paul Zizka/plainpicture)

Santa Cruz River, Patagonia, Argentina (© Coolbiere Photograph/Getty Images)

Gray wolf with begging pup, Montana (© Tim Fitzharris/Minden Pictures)