Male muskoxen near Prudhoe Bay in Alaska, USA (© Oliver Smart/Alamy)

Sunrise at Mount Fuji, Japan (© Juan Paulo Gutierrez/Getty Images)

The whirlpool in Myllykoski scenic area at winter in Oulanka National Park, Kuusamo, Finland (© Lassi Rautiainen/Minden Pictures)

Field of Light at Sensorio, by Bruce Munro, Paso Robles, California, USA (© George Rose/Getty Images)

Sperm whale mother and albino baby swimming off the coast of Portugal (© Flip Nicklin/Minden Pictures)

Burrowing parrots in Las Lajas, Argentina (© Cagan Hakki Sekercioglu/Getty Images)

Trakai Island Castle Museum in Trakai, Lithuania (© Andrius Aleksandravicius/Alamy)

Moons of Jupiter - Io, Europa, Ganymede and Callisto (© Branko Šimunek/Alamy)

Tianmen Mountain in Zhangjiajie, China (© Bogdan Dyiakonovych/Shutterstock)

Dolwyddelan Castle, Snowdonia National Park, Conwy (© Sebastian Wasek/Sime/eStock Photo)

Flags outside the UN's Palace of Nations in Geneva, Switzerland (© Mustafa Yalcin/Anadolu Agency/Getty Images)

Small rakan statues line the stone pathway to the Daisho-in Temple, Miyajima, Japan (© Malcolm Fairman/Alamy)

Eibsee lake at the base of Zugspitze mountain, Bavaria, Germany (© Marc Hohenleitner/Huber/eStock Photo)

A mountain hare hunkers down in a snow storm, the Cairngorms (© Lyle McCalmont/Getty Images)

Aerial view of Boudhanath stupa in Kathmandu, Nepal (© Maksim Semin/Shutterstock)

Sunset in Val Gardena in the Dolomites of South Tyrol, Italy (© Marco Capellari/Getty Images)

A Brandt's cormorant in a school of Pacific mackerel beneath an oil rig off the coast of California, USA (© Alex Mustard/Minden Pictures)

Gypsum sand dunes, White Sands National Park, New Mexico, USA (© Grant Kaye/Cavan Images)

Alex Peterson speed riding on the south side of Mount Hood, Oregon, USA (© Richard Hallman/DEEPOL by plainpicture)

The glaciers and mountains of Kluane National Park and Reserve, Yukon, Canada (© Robert Postma/plainpicture)

Eurasian red squirrel in the Cairngorms (© Images from BarbAnna/Getty Images)

Northern lights near Whitehorse in Yukon, Canada (© Design Pics/Danita Delimont)

Zebras and wildebeest in the Serengeti National Park in Tanzania (© Raffi Maghdessian/Cavan Images)

Sunlit ridges against volcanic scree on Eyjafjallajökull, Iceland (© Erlend Haarberg/Minden Pictures)

The Falls of Bruar, Perthshire (© Peter Watson/Superstock)

The Taj Mahal for India's Republic Day (© Michele Falzone/plainpicture)

View of New York City, USA, from the International Space Station (© NASA Photo/Alamy)

Hoar frost on vegetation near Coniston, Lake District (© Ashley Cooper/Getty Images)

Semuc Champey nature park in Guatemala (© Joel Sharpe/Getty Images)

Aerial view of car crossing over the frozen surface of Lake Baikal, Russia (© Amazing Aerial Agency/Offset)

A reddish egret hunts in Fort De Soto Park, Florida, USA (© Brian Lasenby/Getty Images)