Union Square in lower Manhattan at twilight, New York (© Sean Pavone/Getty Images)

'Vanishing Point' by French street artist JR on the facade of Palazzo Farnese, Rome, Italy (© Fabrizio Troiani/Alamy)

Beech trees and wild anemones, Jutland, Denmark (© Nick Brundle Photography/Getty Images)

A rainbow in At-Bashy District , Kakshaal Too Mountains, Naryn Province, Kyrgyzstan (© Emad aljumah/Getty Images)

Red lechwe herd crossing marshy plain of Okavango Delta, Botswana (© Ibrahim Suha Derbent/Getty Images)

姬路城，姫路，兵库县，日本 (© Julian Elliott Photography/Getty Images)

Himeji Castle, Himeji, Hyōgo Prefecture, Japan (© Julian Elliott Photography/Getty Images)

North American beaver in a pond near Wonder Lake, Denali National Park, Alaska (© Paul Souders/Getty Images)

Total solar eclipse photographed from Madras, Oregon on August 21, 2017 (© NASA/Aubrey Gemignani)

Tulip fields in spring, Skagit Valley, Washington (© Claudia Cooper/Getty Images)

Burrowing owl chicks near a burrow, Wyoming (© Danita Delimont/Getty Images)

Aerial view of Churún Merú waterfall, Venezuela (© AirPano LLC/Amazing Aerial Agency)

Evening light over North Window with Turret Arch in the distance, Arches National Park, Utah (© Anthony Heflin/Shutterstock)

Apple trees in spring, Germany (© Smileus/Getty Images)

Sunset on Bowling Ball Beach, Mendocino County, California (© Melo Qiao/Getty Images)

The RedBall Project art installation, Centraal Station, Antwerp, Belgium (© Brit Worgan/Getty Images)

American black bear cub in spring, Shenandoah National Park, Virginia (© Scott Suriano/Getty Images)

Medieval city walls, Ávila, Spain (© Alberto Loyo/Getty Images)

The Ring of Brodgar, Orkney, Scotland (© Paul Williams - FunkyStock/Getty Images)

Grand Prismatic Spring at sunrise, Yellowstone National Park, Wyoming (© XIN WANG/Getty Images)

Sparks Lane in Cades Cove, Great Smoky Mountains National Park, Tennessee (© Richard Bernabe/Shutterstock)

Green sea turtle, San Diego, California (© Ralph Pace/Minden Pictures)

Library of Trinity College Dublin, Ireland (© Vincent Isore/Getty Images)

White trilliums blooming in Ontario, Canada (© Jun Zhang/Getty Images)

Adélie penguins on an iceberg, Antarctica (© Patrick J. Endres/Getty Images)

Tree of Life, Kalaloch Beach, Olympic National Park, Washington (© Abbie Warnock-Matthews/Shutterstock)

Leucistic Anna's hummingbird in the Australian Garden, UC Santa Cruz Arboretum, California (© yhelfman/Getty Images)

El Capitan at sunrise in Guadalupe Mountains National Park, Texas (© Adam Mowery/Tandem Stills + Motion)

Fujian Tulou complex of historical and cultural heritage buildings in Fujian province, China (© Hongjie Han/Getty Images)

Cheetah in morning rain, Ndutu Plains, Ngorongoro Conservation Area, Tanzania (© Paul Souders/Getty Images)