Mount Etna erupting in 2013, Sicily, Italy (© Wead/Alamy Live News)

Volcano Llaima with Araucaria trees in the foreground, Conguillío National Park, Chile (© Fotografías Jorge León Cabello/Getty Images)

Two female lions in the forest surrounding Lake Nakuru, Kenya (© Scott Davis/Tandem Stills + Motion)

Nusa Dua coast with breakwater, Bali, Indonesia (© Dkart/Getty Images)

Mineral-laden water in the Rio Tinto in Minas de Rio Tinto mining area, Huelva province, Andalusia, Spain (© David Santiago Garcia/Getty Images)

Komodo National Park, Labuan Bajo, Flores, Indonesia (© Thrithot/Adobe Stock)

Great blue herons in the Wakodahatchee Wetlands, Delray Beach, Florida (© Marie Hickman/Getty Images)

Great blue herons in the Wakodahatchee Wetlands, Delray Beach, Florida, USA (© Marie Hickman/Getty Images)

Foothills of the Diablo Range near San Jose, California (© Jeff Lewis/Tandem Stills + Motion)

Traditional farmhouses at Skaftafell, Vatnajökull National Park, Iceland (© Jarcosa/Getty Images)

Kedarnath temple and mountains in Uttarakhand, India (© Shakti Om Singh/EyeEm/Getty Images)

A balloon flies over the Pyramid of the Sun at sunrise in Teotihuacan, Mexico (© Marco Ugarte/AP Photo)

Three stupa with Nubra Valley in the background in Ladakh, India (© Puripat Lertpunyaroj/Getty Images)

Lyon astronomical clock, Lyon, France (© kyolshin/Alamy)

Screech owl resting in a tree cavity, Massapequa Preserve, Long Island, New York (© Vicki Jauron, Babylon and Beyond Photography/Getty Images)

Giant panda cub in Bifengxia Panda Base, Sichuan, China (© Suzi Eszterhas/Minden Pictures)

Inisheer, the smallest of the three Aran Islands in Galway Bay, Ireland (© Chris Hill/Minden Pictures)

Aerial view of the 'City of Adelaide' shipwreck with trees growing on it, Magnetic Island, Queensland, Australia (© Amazing Aerial Agency/Offset by Shutterstock)

Aerial view of the 'City of Adelaide' shipwreck with trees growing on it, Magnetic Island, Queensland, Australia (© Amazing Aerial Agency/Offset by Shutterstock)

Bluebell flowers carpet the Hallerbos forest floor, Flanders, Belgium (© Jason Langley/plainpicture)

Mahabodhi Temple in Bodh Gaya, Bihar, India (© Tinnaporn Sathapornnanont/Shutterstock)

Satellite image of the Mania River in Madagascar (© NASA Earth Observatory image by Joshua Stevens, using Landsat data from the US Geological Survey)

Humpback whale mother pushes her sleeping calf to surface, Maui, Hawaii (© Ralph Pace/Minden Pictures)

Spring ice along the shore of Lake Winnipeg, Manitoba (© Mike Grandmaison/Jaynes Gallery/DanitaDelimont.com)

Cradle Mountain-Lake St. Clair National Park, Tasmania, Australia (© Paparwin Tanupatarachai/Getty Images)

Mountain hare running across snow-covered upland, Scotland (© SCOTLAND: The Big Picture/Minden Pictures)

Mount Snowdon and the Llanberis Pass from Dinorwic Slate Quarry, Snowdonia National Park, North Wales, UK (© Alan Novelli/Alamy Stock Photo)

People celebrating Holi in India (© Laura Saffioti/EyeEm/Getty Images)

Detail of an ostrich fern in spring, Washington state (© Stephen Matera/Tandem Stills + Motion)

Wayag Island at Raja Ampat, Indonesia (© Amazing Aerial Agency/Offset by Shutterstock)

Wayag Island, Raja Ampat, Indonesia (© Amazing Aerial Agency/Offset by Shutterstock)