Claret cup cactus, Guadalupe Mountains National Park, Texas (© Clint Farlinger/Alamy)(Bing United States)

Claret cup cactus, Guadalupe Mountains National Park, Texas (© Clint Farlinger/Alamy)(Bing United States)

Bison at Wind Cave National Park, South Dakota (© Newman Mark/SuperStock)(Bing United States)

Bison at Wind Cave National Park, South Dakota (© Newman Mark/SuperStock)(Bing United States)

Satellite view of Everglades National Park, Florida (© Satellite Earth Art/Aurora Photos)(Bing United States)

Satellite view of Everglades National Park, Florida (© Satellite Earth Art/Aurora Photos)(Bing United States)

Visitors at the summit of Haleakalā at Haleakalā National Park, Hawaii (© Alex Messenger/Tandem Stills + Motion)(Bing United States)

Visitors at the summit of Haleakalā at Haleakalā National Park, Hawaii (© Alex Messenger/Tandem Stills + Motion)(Bing United States)

Alaska Peninsula brown bear, Katmai National Park and Preserve, Alaska (© Suzi Eszterhas/Minden Pictures)(Bing United States)

Alaska Peninsula brown bear, Katmai National Park and Preserve, Alaska (© Suzi Eszterhas/Minden Pictures)(Bing United States)

Grand Prismatic Spring at Yellowstone National Park (© Media Drum World/Aurora Photos)(Bing United States)

Grand Prismatic Spring at Yellowstone National Park (© Media Drum World/Aurora Photos)(Bing United States)

Leaf insect, Indonesia (© kuritafsheen/RooM/Getty Images)(Bing United States)

Leaf insect, Indonesia (© kuritafsheen/RooM/Getty Images)(Bing United States)

Craig Goch Dam in the Elan Valley of Wales (© Stephen Taylor/Alamy)(Bing United States)

Craig Goch Dam in the Elan Valley of Wales (© Stephen Taylor/Alamy)(Bing United States)

A crested partridge (© Sue Demetriou/Offset)(Bing United States)

A crested partridge (© Sue Demetriou/Offset)(Bing United States)

The Children's Cultural Festival at Harpa Concert Hall in Reykjavik, Iceland (© Arctic-Images/Corbis Documentary/Getty Images)(Bing United States)

The Children's Cultural Festival at Harpa Concert Hall in Reykjavik, Iceland (© Arctic-Images/Corbis Documentary/Getty Images)(Bing United States)

The Bazaruto Archipelago of Mozambique (© Jody MacDonald/Offset)(Bing United States)

The Bazaruto Archipelago of Mozambique (© Jody MacDonald/Offset)(Bing United States)

The ‘Living Forest’ in the Oma Valley of Biscay, Spain (© Juan Carlos Munoz/Minden Pictures)(Bing United States)

The ‘Living Forest’ in the Oma Valley of Biscay, Spain (© Juan Carlos Munoz/Minden Pictures)(Bing United States)

A pod of dusky dolphins at Kaikoura, New Zealand (© Terry Whittaker/Alamy)(Bing United States)

A pod of dusky dolphins at Kaikoura, New Zealand (© Terry Whittaker/Alamy)(Bing United States)

Replica of a Viking home in Dublin National Botanic Gardens, Ireland (© George Munday/plainpicture)(Bing United States)

Replica of a Viking home in Dublin National Botanic Gardens, Ireland (© George Munday/plainpicture)(Bing United States)

Sydney Harbour Bridge in Sydney, Australia (© Grant Faint/Offset)(Bing United States)

Sydney Harbour Bridge in Sydney, Australia (© Grant Faint/Offset)(Bing United States)

Zhangjiajie National Forest Park in Hunan Province, China (© aphotostory/Shutterstock)(Bing United States)

Zhangjiajie National Forest Park in Hunan Province, China (© aphotostory/Shutterstock)(Bing United States)

Baby and juvenile elephants in Amboseli National Park in Kenya (© Tom Stahl/Offset)(Bing United States)

Baby and juvenile elephants in Amboseli National Park in Kenya (© Tom Stahl/Offset)(Bing United States)

The Lena Delta Wildlife Reserve in Siberia, Russia (© USGS EROS Data Center/NASA)(Bing United States)

The Lena Delta Wildlife Reserve in Siberia, Russia (© USGS EROS Data Center/NASA)(Bing United States)

Male resplendent quetzal in Costa Rica (© mallardg500/Getty Images)(Bing United States)

Male resplendent quetzal in Costa Rica (© mallardg500/Getty Images)(Bing United States)

The Arve River (right) flowing into the Rhône in Geneva, Switzerland (© Capchure/Getty Images)(Bing United States)

The Arve River (right) flowing into the Rhône in Geneva, Switzerland (© Capchure/Getty Images)(Bing United States)

Emperor penguins on Snow Hill Island, Antarctica (© David Tipling Photo Library/Alamy)(Bing United States)

Emperor penguins on Snow Hill Island, Antarctica (© David Tipling Photo Library/Alamy)(Bing United States)

Mada’in Saleh archeological site in Saudi Arabia (© Bruno Zanzottera/Aurora Photos)(Bing United States)

Mada’in Saleh archeological site in Saudi Arabia (© Bruno Zanzottera/Aurora Photos)(Bing United States)

Mexican giant cardon cactus (© Ed Reardon/Alamy)(Bing United States)

Mexican giant cardon cactus (© Ed Reardon/Alamy)(Bing United States)

The village of Castelluccio above the Piano Grande, Umbria, Italy (© beppeverge/Getty Images)(Bing United States)

The village of Castelluccio above the Piano Grande, Umbria, Italy (© beppeverge/Getty Images)(Bing United States)

Seven Magic Mountains art installation, Jean Dry Lake, Nevada (© Renz Alfonso Dela Pena)(Bing United States)

Seven Magic Mountains art installation, Jean Dry Lake, Nevada (© Renz Alfonso Dela Pena)(Bing United States)

The marshmallow PEEPS® factory in Bethlehem, Pennsylvania (© Kristoffer Tripplaar/Alamy)(Bing United States)

The marshmallow PEEPS® factory in Bethlehem, Pennsylvania (© Kristoffer Tripplaar/Alamy)(Bing United States)