Ruby-throated hummingbird feeding on yellow bells in the Texas Hill Country (© Rolf Nussbaumer/Danita Delimont)

Oyster mushrooms in Belgium (© Philippe Clement/Minden Pictures)

Smith Rock State Park, Oregon (© Manuela Durson/Getty Images)

Lujiazui Financial District, Shanghai, China (© Jackal Pan/Getty Images)

A bull in the foothills of Mount Pico on Pico Island in the Portuguese archipelago of the Azores (© Atmo-Sphere/Getty Images)

Beaver dam in the Sawtooth National Forest, Idaho (© Charles Knowles/Alamy)

Reedy Island in Moneyboque Bay, Long Island, New York (© Claudia Uripos/eStock Photo)

A worker painting the Hammering Man, a sculpture by Jonathan Borofsky, in Frankfurt, Germany (© Arne Dedert/Alamy)

Valletta, Malta (© Deejpilot/Getty Images)

A bearded reedling in Elmley National Nature Reserve in Kent, England (© Mark Bridger/Offset by Shutterstock)

Huay Mae Khamin waterfall in Khuean Srinagarindra National Park, Thailand (© ImpaKPro/Getty Images)

One World Trade Center and lower Manhattan, seen from the Empty Sky memorial in Jersey City, New Jersey (© Maurizio Rellini/Offset by Shutterstock)

Rocamadour, France (© Rrrainbow/Getty Images)

Sand dunes with Sangre de Cristo Mountains in the background, Great Sand Dunes National Park and Preserve, Colorado (© Tim Fitzharris/Minden Pictures)

'Out of Many, One,' an artwork by Jorge Rodríguez-Gerada on the National Mall in Washington, DC (© Keith Lane/Tribune News Service via Getty Images)

Guanajuato, Mexico (© AI NISHINO/Alamy)

The US Constitution and the Declaration of Independence on display in the National Archives, Washington, DC (© Carol M. Highsmith/Buyenlarge/Getty Images)

Icelandic sheep ready for réttir (© Pieter Tytgat/Getty Images)

Sailboats in Warnemünde, Germany (© Rico Ködder/Getty Images)

Sea otter mother and newborn pup in Monterey Bay, California (© Suzi Eszterhas/Minden Pictures)

The Ship of Tolerance, an international art installation in Zug, Switzerland (© Linda Kennard/Alamy)

Hobbiton, near Matamata, North Island, New Zealand (© 500px Asia/Getty Images)

Golden ginkgo leaves at Xuanwu Lake Park in Nanjing, Jiangsu province, China (© SIPA Asia/ZUMA Wire/Alamy)

Cows decorated for the Almabtrieb in Tannheimer Tal, a valley in Tyrol, Austria (© Hans Lippert/Alamy)

Ceiling and cove of the Great Hall at the Library of Congress in Washington, DC (© Susan Candelario/Alamy)

Watkins Glen State Park's Rainbow Falls in the Finger Lakes region of upstate New York (© Kenneth Keifer/Alamy)

The Fraser River, east of Vancouver, British Columbia, Canada, with the Golden Ears mountains (© LeonU/Getty Images)

Blue shark near the Azores in the North Atlantic Ocean (© Nuno Sa/Minden Pictures)

Steeply terraced vineyards of the Lavaux region on the shores of Lake Geneva, Switzerland (© Yves Marcoux/plainpicture)

A saturniid moth in Mole National Park in Larabanga, Ghana (© Robert Thompson/Minden Pictures)