Old underground cellar, Bavaria, Germany (© Andreas Zerndl/Getty Images)

Javan tree frog (© kuritafsheen/Getty Images)

Bromo Tengger Semeru National Park, East Java, Indonesia (© Bento Fotography/Getty Images)

Pu'uhonua o Hōnaunau National Historical Park, Big Island, Hawaii (© Westend61/Getty Images)

Roman bridge, Córdoba, Spain (© Jeremy Woodhouse/Getty Images)

Black grouse males in Kuusamo, Finland (© Markus Varesvuo/Minden Pictures)

Moon rising, Tucson, Arizona (© Tim Murphy/Shutterstock)

Baby Eurasian beavers, Finland (© Danny Green/Minden Pictures)

The Giant's Causeway, County Antrim, Northern Ireland (© Dieter Meyrl/Getty Images)

Lithuanian Easter eggs (© fotomem/Getty Images)

Elephant family in Amboseli National Park, Kenya (© Diana Robinson/Getty Images)

Mossy Grotto Falls, Columbia River Gorge, Oregon (© Chase Dekker Wild-Life Images/Getty Images)

Earth seen from the International Space Station (© Tim Peake/ESA/NASA via Getty Images)

Moss pink displays at Hitsujiyama Park, Saitama Prefecture, Japan (© Takashi Images/Shutterstock)

Mediterranean red sea stars, Mediterranean Sea (© Hans Leijnse/Minden Pictures)

'Together' sculpture by Lorenzo Quinn, Great Pyramids of Giza, Cairo, Egypt (© Sima Diab/Getty Images)

Adelaide International Kite Festival, Australia (© Andrey Moisseyev/Alamy)

'One Thousand Springs' haiku art installation by Chiharu Shiota, Kew Royal Botanic Gardens, London, England (© Guy Bell/Alamy Live News)

Machu Picchu, Peru (© Dora Dalton/Getty Images)

Taiwan yuhina pair, Alishan National Scenic Area, Taiwan (© Staffan Widstrand/Minden Pictures)

Juniper Springs in Ocala National Forest, Florida (© Michael Warren/Getty Images)

Procida, Italy (© Sean Pavone/Shutterstock)

Island fox in Channel Islands National Park, California (© Ian Shive/Tandem Stills + Motion)

Stuttgart Public Library, Germany (© Axel Brunst/Tandem Stills + Motion)

Adélie penguins in Antarctica (© David Merron Photography/Getty Images)

Great horned owl fledglings (© Michael Morse/Getty Images)

South Padre Island, Texas (© Jeff R Clow/Getty Images)

Mariposa Grove of Giant Sequoias in Yosemite National Park, California (© Orbon Alija/Getty Images)

Milky Way over Joshua Tree National Park, California (© Schroptschop/Getty Images)

Preservation Hall, New Orleans, Louisiana (© Cosmo Condina North America/Alamy)