Pale-throated sloth perched in a tree on Sloth Island, Essequibo River, Guyana (© Suzi Eszterhas/Minden Pictures)

Painting of Gandhi inside Gandhi Memorial Museum, Madurai (© db images/Alamy Stock Photo)

The Trossachs National Park in autumn, Stirling, Scotland (© Jon Arnold/Danita Delimont)

Sequence of enhanced-color images of Jupiter (© Enhanced Image by Gerald Eichstädt and Sean Doran, CC BY-NC-SA, based on images provided Courtesy of NASA/JPL-Caltech/SwRI/MSSS)

Tintern Abbey, Wales (© Lynda Morris Photography/Getty Images)

Aerial view of Marlborough Sounds, New Zealand (© Mathias Ortmann/Getty Images)

Cleveland Clinic Lou Ruvo Center for Brain Health in Las Vegas, Nevada, USA (© Garry Belinsky/Offset)

Air show at Bamhrauli Air station, 2017 (© CrowdSpark/Alamy Stock Photo)

Letchworth State Park, New York (© Jay O'Brien/Danita Delimont)

Bubble Nebula (NGC 7635) (© NASA, ESA, and the Hubble Heritage Team STScI/AURA)

Tomb of I'timad-ud-Daulah, or Baby Taj in Agra (© Cristian Baitg/Moment/Getty Images)

Boats massing for the Barcolana Regatta in the Gulf of Trieste, Italy (© Ababsolutum/E+/Getty Images)

A fossilized carboniferous fern (© Juan Carlos Munoz/Minden Pictures)

Sunrise in Alberta, Canada (© Ambre Haller/Moment/Getty Images)

Close-up of a dragonfly wing (© Azwar Thaufeeq/500px/Getty Images)

Highbush blueberry plants in Acadia National Park, Maine, USA (© Danita Delimont/Gallo Images/Getty Images Plus)

Colourful bangles in a market, Andhra Pradesh (© Tim Gainey/Alamy Stock Photo)

Chimney Rock and Uncompahgre National Forest, Colorado, USA (© Cory Marshall/Tandem Stills + Motion)

Aerial view of a pumpkin patch in Half Moon Bay, California (© Tinker Street/Michael O'Neal/Gallery Stock)

Ashdown Forest, Misty Sunrise, East Sussex, United Kingdom (© Tim Stocker Photography/Getty Images)

Blackbird eating a crab apple in a garden in Wiltshire, United Kingdom (© Nick Upton/Minden Pictures)

A polar bear family near the Hudson Bay in Churchill, Manitoba, Canada (© Marco Pozzi Photographer/Getty Images)

County Bridge in New Hampshire, USA (© Denis Tangney Jr/E+/Getty Images)

Ring-tailed lemurs in Madagascar for World Lemur Day (© Image Source/Alamy)

Klaus Littmann's 'FOR FOREST: The Unending Attraction of Nature' in Wörthersee Stadion, Klagenfurt, Austria (© UNIMO)

Diwali rangoli and diyas in Varanasi, U.P. (© Subir Basak/Getty Images)

Fort Rock Valley Historical Homestead Museum, Oregon, USA (© Prisma by Dukas Presseagentur GmbH/Alamy)

Straw-coloured fruit bats in Kasanka National Park, Zambia (© Nick Garbutt/Minden Pictures)

Charles Bridge over the Vltava River in Prague (© Martin Moxter/Offset)

Corvin Castle, Romania (© DCPmedia/Shutterstock)

Chandra Tal lake in the Spiti region, Himachal Pradesh (© f9photos/Getty Images Plus)