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

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

Statue of Hans Christian Andersen in New York City’s Central Park (© Stuart Forster/Shutterstock)

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

For Earth Month, a symmetrical forest known as a Nelder plot (© Rachid Dahnoun/Tandem Stills + Motion)

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

Pepper, SoftBank Robotics' humanoid robot, on display in Tokyo (© Christopher Jue/EPA/Shutterstock)

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

Interior of Seattle Public Library’s Central Library (© Ron Buskirk/Alamy)

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

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)

Vinyl records in Rosmalen, Netherlands (© DutchScenery/Shutterstock)

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)

Hope Valley, Peak District, England (© Daniel_Kay/Getty Images Plus)

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

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

The Cove of Spires in Kenai Fjords National Park near Seward, Alaska (© Grant Ordelheide/Tandem Stills + Motion)

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 Sant 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 Vatnajökull National Park, Iceland (© Johnathan Ampersand Esper/Aurora Photos)

Coast redwoods in Henry Cowell Redwoods State Park, California (© Gallery Stock)

Hummingbird near blooming aloe plants 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)