A polar bear sow and her cubs in Alaska's Arctic National Wildlife Refuge (© Steven Kazlowski/Minden Pictures)

Skating on the Rideau Canal during Winterlude in Ottawa (© Preappy/Getty Images)

Meerkat family huddling together (© stefbennett/Shutterstock)

Moai statues at Ahu Tongariki in Rapa Nui National Park, Easter Island, Chile (© blickwinkel/Alamy)

Sigiriya Rock, Central Province, Sri Lanka (© Jeremy Woodhouse/Getty Images)

A snowdrop in bloom (© Péter Hegedűs/Getty Images)

View of the Old City in Quebec City, Canada (© RENAULT Philippe/age fotostock)

View of the Old City in Quebec City (© RENAULT Philippe/age fotostock)

Lantern Festival in Pingxi, Taiwan (© Jung-Pang Wu/Getty Images)

Boats resting between the Granville Bridge and the Burrard Bridge in False Creek, Vancouver (© Greg Norgaard/Alamy Stock Photo)

Aerial view of Superkilen Park in Norrebro district in Copenhagen, Denmark (© Oliver Förstner/Alamy)

Dr. Sylvia Earle explores the Great Barrier Reef in a scene from 'Mission Blue' (© Bryce Groark/AP Photo/Netflix)

Couple de Demi-deuil sur une fleur, Alsace, France (© Eric Ferry/Minden Pictures)

Frozen colosseum of ice sticking to the columnar basalt walls surrounding Abiqua Falls, Oregon (© Joshua Meador/Tandem Stills + Motion)

A heart-shaped hole in the rock formation of Calanques de Piana in Corsica, France (© joningall/Getty Images)

Canadian flags are printed at the Flags Unlimited facility in Barrie, Ont. (© Brent Lewin/Bloomberg via Getty Images)

Frozen colosseum of ice sticking to the columnar basalt walls surrounding Abiqua Falls, Oregon, USA (© Joshua Meador/Tandem Stills + Motion)

Pluto's crescent imaged by NASA's New Horizons interplanetary space probe (© NASA/JHUAPL/SWRI/Science Photo Library)

Pluto's crescent imaged by NASA's New Horizons interplanetary space probe (© NASA/JHUAPL/SWRI/Science Photo Library)

Wandering albatross pair, South Georgia and the South Sandwich Islands (© David Tipling Photo Library/Alamy)

Rifugio Lagazuoi above the clouds with Monte Pelmo in the background, Dolomites, Italy (© Nicolo Miana/eStock Photo)

Giant puppets for Carnival in Olinda, Brazil (© Pulsar Imagens/Alamy)

The interior of the Great Temple of Ramesses II, Abu Simbel, Egypt (© Nick Brundle Photography/Getty Images)

People ice fishing on Gull Lake in Brainerd, Minnesota (© Robert Benson/Cavan)

Pilgrims throwing wind horses into the air above Ganden Monastery for the New Year in Tibet, China (© Ian Cumming/plainpicture)

The Roots of Music Cultural Sculpture Garden in Louis Armstrong Park, New Orleans, LA (© jejim120/Alamy)

Acadia National Park in Maine (© emptyclouds/Getty Images)

Otter Creek in winter in Brandon, Vermont (© Caleb Kenna/Offset)

A Wallace's flying frog glides to the forest floor (© Stephen Dalton/Minden Pictures)