Three-toed sloth in Costa Rica (© Harry Collins/Getty Images)

Last light on Half Dome, Yosemite National Park, California (© Adam Burton/Alamy)

Wind River, Brooks Range, Arctic National Wildlife Refuge, Alaska (© Design Pics/Danita Delimont)

Taj Mahal in Agra, Uttar Pradesh, India (© Tanarch/Getty Images)

Jupiter's icy moon Europa (© NASA/JPL-Caltech/SETI Institute)

African elephants in Tsavo East National Park, Kenya (© Neil Bowman/Minden Pictures)

Sorano, Tuscany, Italy (© Luigi Vaccarella/eStock Photo)

The Elbphilharmonie concert hall in Hamburg, Germany (© Canetti/Shutterstock)

Mototi octopus, Lembeh Strait, Indonesia (© Howard Chew/Alamy)

Aspens in the White River National Forest, Colorado (© Jason Hatfield/Tandem Stills + Motion)

Kochia, Ibaraki prefecture, Japan (© DigiPub/Getty Images)

Cape Breton Highlands, Nova Scotia, Canada (© Cavan Images/Alamy)

Wood duck, Quebec, Canada (© Maxime Riendeau/Getty Images)

Courtyard of the Maidens, Alcázar of Seville, Spain (© Danny Lehman/Getty Images)

Ancestral Pueblo granaries at Nankoweap, Grand Canyon National Park, Arizona (© Andrew Peacock/Tandem Stills + Motion)

Great wildebeest migration at Mara River, Kenya (© Ayzenstayn/Getty Images)

Fossils of belemnites and ammonites, Jurassic Coast, Dorset, England (© Nature Picture Library/Alamy)

Frost-covered dunes on the surface of Mars (© NASA/JPL-Caltech/UArizona)

Autumn in Central Park, Manhattan, New York (© mapman/Shutterstock)

Temple of Hathor, Dendera Temple Complex, Qena, Egypt (© Nick Brundle Photography/Getty Images)

Cypress trees in George L. Smith State Park, Georgia (© Chris Moore/TANDEM Stills + Motion)

Palazzo Zuccari, Rome, Italy (© Photon-Photos/Getty Images)

Madame Sherri Forest and the ruins of an old castle, New Hampshire (© yggdrasill/Shutterstock)

Bodie State Historic Park, Mono County, California (© Julien McRoberts/Tetra Images, LLC/Alamy)

The Mont Blanc massif, near Chamonix, France (© Simon Schöpf/Getty Images)

Gespensterwald, Nienhagen, Mecklenburg-West Pomerania, Germany (© mauritius images GmbH/Alamy)

Polar bear mom and cub, Churchill, Manitoba, Canada (© Design Pics/plainpicture)

Pumpkin field, Victoria, British Columbia, Canada (© Shaun Cunningham/Alamy)

Great horned owl (© Mark Newman/Getty Images)

View of Edinburgh Castle from a churchyard in Scotland (© Chris Dorney/Alamy)

Chimera of Notre-Dame de Paris, France (© scaliger/Getty Images)