Rosa Parks sits in the front of a bus in Montgomery, Alabama, Dec 21, 1956 (© Bettmann Archive/Getty Images)

'Testament: The Little Rock Nine Monument,' Little Rock, Arkansas (© Rex Lisman/Getty Images)

Alpine marmots in Hohe Tauern National Park, Austria (© Michaela Walch/Alamy)

Château Frontenac, Quebec City, Canada (© Romiana Lee/Shutterstock)

Monarch butterflies at Pismo Beach, California (© Mimi Ditchie/Getty Images)

Fiordland National Park in South Island, New Zealand (© WitR/Adobe Stock)

Village of Labro, Rieti Province, Italy (© Marco Ilari/Shutterstock)

Ureddplassen, a rest area on the Helgelandskysten scenic route, Norway (© Eyesite/Alamy)

Lower Antelope Canyon near Page, Arizona (© AZCat/Getty Images)

Ancient theater of Epidaurus in Argolis province, Greece (© George Pachantouris/Getty Images)

The Milky Way over Zabriskie Point, Death Valley, California (© Matt Anderson Photography/Getty Images)

Blue-footed booby, Galápagos Islands, Ecuador (© Tui De Roy/Minden Pictures)

Achaches lookout, El Valle de la Luna, Chile (© Ignacio Palacios/Getty Images)

Igloo at Otaru Snow Light Path Festival, Hokkaido, Japan (© T Photography/Shutterstock)

Hippopotamus mother and baby, Chobe National Park, Botswana (© jacobeukman/Getty Images)

'Firefall' on Horsetail Fall, Yosemite National Park, California (© Jeff Lewis/Tandem Stills + Motion)

Allen's hummingbird perched on a red kangaroo paw plant (© GypsyPictureShow/Shutterstock)

Eben Ice Caves, Upper Peninsula, Michigan (© Dean Pennala/Shutterstock)

Humpback whales, Maui, Hawaii (© Flip Nicklin/Minden Pictures)

Washington Monument and Capitol Building on the National Mall, Washington, DC (© AevanStock/Shutterstock)

French Quarter, New Orleans, Louisiana (© f11photo/Getty Images)

Freedom Sunday rally, Soldier Field, Chicago, Illinois, July 10, 1966 (© Bettmann/Getty Images)

Paris, France (© somchaij/Shutterstock)

Mandarin duck, Richmond Park, London, England (© Oscar Dewhurst/Minden Pictures)

Hoodoos at Bryce Canyon National Park, Utah (© Piriya Photography/Getty Images)

Suspension bridge in Tambopata National Reserve, Amazon Basin, Peru (© Pere Rubi/Getty Images)

Polar bears asleep in Canada (© David Pike/Minden Pictures)

Atrani, Amalfi Coast, Italy (© Amazing Aerial/Shutterstock)