For Siblings Day, lion cubs wrestle in Samburu National Park, Kenya (© Mark C. Ross/Getty Images)

Bear cubs playing by a lake (© Sergey Ivanov/Getty)

Books by Hans Christian Andersen (© radiokafka/Adobe Stock)

Milky way over the Bisti/De-Na-Zin Wilderness in New Mexico (© Cory Marshall/Tandem Stills + Motion)

Emerald Lake near Carcross, Yukon Territories (© David Noton Photography/Alamy Stock Photo)

Blossoming cherry trees at a tea plantation in Longyan, China (© VCG/Getty Images)

Bioluminescent algae along the shores of the Matsu Islands off the coast of Taiwan (© Wan Ru Chen/Getty Images)

For International Beaver Day a beaver swimming in Grand Teton National Park (© Charlie Hamilton James/Getty Images)

The National Wallace Monument overlooking Stirling in Scotland (© Elena Korchenko/age fotostock)

Reflection of the Vimy Memorial Bridge in Ottawa (© Saffron Blaze/Getty Images)

Dutch tulip fields in the Duin- en Bollenstreek region for the Amsterdam Tulip Festival (© Frans Sellies/Getty Images)

The Mount Washington Observatory in New Hampshire (© Mike Theiss/Getty Images)

通往圣胡安·加兹特鲁加特的道路，西班牙巴斯克 (© Anton Petrus/Moment/Getty Images)

Path to San Juan de Gaztelugatxe, Basque Country, Spain, for the 'Game of Thrones' premiere (© Anton Petrus/Moment/Getty Images)

石楠花丛中的雄狍 (© wonderful-Earth.net/Alamy Stock Photo)

Bauhaus Archive Museum of Design in Berlin, Germany (© Juergen Henkelmann Photography/Alamy)

The Esplanade Riel Bridge in downtown Winnipeg (© Design Pics Inc/Alamy Stock Photo)

Dubai Miracle Garden, United Arab Emirates (© Amazing Aerial/Offset)

Paepalanthus flowers at sunset, Chapada dos Veadeiros National Park, Brazil (© Marcio Cabral/Getty Images)

Chipmunk storing food in his cheeks (© mlorenzphotography/Getty Images)

A rabbit in the grass (© wisan224/Getty Images Plus)

Laysan albatross chick on Midway Atoll, Hawaiian Leeward Islands (© Jaymi Heimbuch/Minden Pictures)

At Casa Batlló for Saint Jordi’s Day in Barcelona, Spain (© Jon Arnold Images Ltd/Alamy)

The Quinault Rainforest in Olympic National Park, Washington (© Jason Savage/Tandem Stills + Motion)

Ice cave at sunset in Vatnajokull, Iceland (© Johnathan Ampersand Esper/Aurora Photos)

View of modern buildings at sunset in downtown Toronto (© Jon Bilous/Shutterstock)

Hummingbird near blooming aloe vera in Laguna Beach, California (© Aurora Photos/Offset)

Prairie and pinnacles near Castle Trail in Badlands National Park, South Dakota (© Danita Delimont/Getty Images)

Newborn brown-throated sloth with mother, Sloth Sanctuary of Costa Rica (© Suzi Eszterhas/Minden Pictures)

Louis Armstrong performs with bandmates in Vienna, Austria, on February 22, 1959 (© Franz Hubmann/Getty Images)