Polar bear cubs playing in Kaktovik, Alaska (© Martin Smart/Alamy)

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

Bruce Munros Installation „Field of Light“, Kulturzentrum Sensorio, El Paso de Robles, Kalifornien, USA (© George Rose/Getty Images)

Pottwalkuh mit ihrem Albino-Kalb vor der Küste von Portugal (© Flip Nicklin/Minden Pictures)

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

特拉凯城堡博物馆，立陶宛特拉凯 (© Andrius Aleksandravicius/Alamy)

木星的卫星——木卫一、木卫二、木卫三和木卫四 (© Branko Šimunek/Alamy)

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

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

一枚红苹果挂在被大雪压断的树枝上 (© griangraf/iStock/Getty Images)

City lights from the snowy peak of Grouse Mountain at twilight, Vancouver, BC, Canada (© Pierre Leclerc Photography/Getty Images)

A red apple clings to a broken branch heavy with snow, Coburg, Bavaria, Germany (© griangraf/iStock/Getty Images)

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

Windmills in the province of Toledo, Spain (© Jon Arnold/Danita Delimont)

Pongal kolam in Tamil Nadu (© Melting Spot/Alamy Stock Photo)

Beach in the evening light at Whisky Bay, Wilsons Promontory National Park, Victoria, Australia (© Michael Breitung/Huber/eStock Photo)

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

Colourful stained-glass window at the CST railway station (earlier Victoria Terminus), Mumbai (© Natalie Solveland/Alamy Stock Photo)

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

阳光照耀下的火山岩山脊，冰岛埃亚菲亚德拉冰盖 (© Erlend Haarberg/Minden Pictures)

Eurasian red squirrel in the Cairngorms, Highlands of Scotland (© Images from BarbAnna/Getty Images)

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

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

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

Red lanterns hanging on branches (© bingdian/iStock/Getty Images Plus)

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

海恩斯章克申附近克鲁瓦尼国家公园中冰川和山脉的鸟瞰图，加拿大育空 (© Robert Postma/plainpicture)

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

汽车穿过贝加尔湖冰面的鸟瞰图，俄罗斯 (© Amazing Aerial Agency/Offset)

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 (© Brian Lasenby/Getty Images)