Altdahn Castle near Dahn, Dahner Felsenland (Dahn Rockland), Palatinate Forest, Rhineland-Palatinate, Germany (© Reinhard Schmid/Huber/eStock Photo)

Deer in the grasslands at Jim Corbett National Park, Uttarakhand, India (© FLPA/Alamy Stock Photo)

Rainbow at Victoria Falls in Zambia (© Dietmar Temps/Shutterstock)

Rainbow at Victoria Falls in Zambia (© Dietmar Temps/Shutterstock)

Green tree frog and purple water lily, Lake Kissimmee, Florida, USA (© Joanne Williams/Danita Delimont)

Jain temples on top of Shantrujaya hill, Palitana, Gujarat (© Aliaksandr Mazurkevich/Alamy Stock Photo)

Flowing clouds over the Atlantic Ocean and Tenerife mountains, Canary Islands, Spain (© MikeMareen/iStock/Getty Images Plus)

The 2017 April full moon, or pink moon, rises over St. Michael's Mount, Cornwall, England (© Simon Maycock/Alamy Live News)

Aerial view of Santorini, Greece (© Amazing Aerial Agency/Offset)

A Kermode bear cub huddling with its sibling in Canada's Great Bear Rainforest, British Columbia, Canada (© Ian McAllister/Offset)

Pantropical spotted dolphins off the coast of Ixtapa, Mexico (© Christian Vizl/Tandem Stills + Motion)

Ancient Roman gold mining site of Las Médulas, León, Spain (© DEEPOL by plainpicture/David Santiago Garcia)

Floating temples of Wat Chaloem Phra Kiat Phrachomklao Rachanusorn in Lampang province, Thailand (© pa_YON/Getty Images)

Multi-pillar canopy and main dome of the Ambedkar Stupa, Uttar Pradesh (© Amlan Mathur/Shutterstock)

Bhagsu waterfalls in the Dharamsala region, Himachal (© f9photos/iStock/Getty Images Plus)

Sipapu Bridge in Natural Bridges National Monument, Utah, USA (© Fyletto/Getty Images)

Sipapu Bridge in Natural Bridges National Monument, Utah (© Fyletto/Getty Images)

Ruffed grouse in Algonquin Provincial Park, Ontario, Canada (© Jim Cumming/Getty Images)

Vernal Fall in Yosemite National Park, California (© elvistudio/Shutterstock)

Milky Way over Neist Point Lighthouse, Isle of Skye, Scotland (© Shaiith/Getty Images)

The Grand Prismatic Spring in Yellowstone National Park, Wyoming, USA (© Martin Rügner/DEEPOL by plainpicture)

Te Matua Ngahere, a giant kauri tree growing in Waipoua Forest, Northland, New Zealand (© Kim Westerskov/Getty Images)

Male king eider ducks swimming in Troms og Finnmark, Norway (© Pal Hermansen/Minden Pictures)

Male king eider ducks swimming in Troms og Finnmark, Norway (© Pal Hermansen/Minden Pictures)

Southern rockhopper penguins on the Falkland Islands (© Heike Odermatt/Minden Pictures)

Sunset at Ruby Beach in Olympic National Park, Washington state, USA (© Adam Mowery/Tandem Stills + Motion)

Detail of ceiling of Safdarjung's Tomb, Delhi (© David Clapp/Getty Images)

Salisbury Cathedral with grazing flock of sheep, England (© Slawek Staszczuk Photo/Alamy)

A tractor kicks up dust while tilling fields on the Palouse near Pullman, Washington, USA (© Ben Herndon/Tandem Stills + Motion)

A tractor kicks up dust while tilling fields on the Palouse near Pullman, Washington (© Ben Herndon/Tandem Stills + Motion)