Red squirrel in heather, Scotland (© Christopher Drabble/Alamy)

Guaita tower in San Marino (© Piercarlo Abate/Shutterstock)

'Vessel' at Hudson Yards in New York City, USA (© Paparacy/Shutterstock)

Tegallalang terrace farms in Ubud, Bali, Indonesia (© gorgeoussab/Shutterstock)

Castillo del Morro in Old San Juan, Puerto Rico (© grandriver/Getty Images)

Mount Fanjing, the highest peak of the Wuling Mountains, in south-west China (© Keitma/Alamy)

Southern yellow-billed hornbills in Kruger National Park, South Africa (© Ben Cranke/Getty Image)

Gerenuk in Tsavo National Park, Kenya (© Byrdyak/iStock/Getty Images Plus)

Aerial view of rainforest and Daintree River, Australia (© Peter Adams/Offset)

The Milky Way seen from Canyonlands National Park in Utah, USA (© Cavan Images/Offset)

Drones light up the sky over Shenzhen, China (© Liang Weiming/VCG via Getty Images)

Walruses near Kvitøya in the Svalbard archipelago, Norway (© Ole Jorgen Liodden/Minden Pictures)

Surfboards in a row (© plainpicture/Tony Arruza)

Wachsenburg Castle, Thuringia, Germany (© Raimund Linke/Masterfile)

The road over Stoke Pero Common, Dunkery Hill, Exmoor, England (© David Noton/Alamy)

The Villarrica volcano in Chile on 2 September, 2018 (© Cristobal Saavedra Escobar/Reuters)

A common loon in Superior National Forest in Minnesota, USA (© Jim Brandenburg/Minden Pictures)

Tokyo cityscape at sunset, Japan (© rudi1976/Alamy)

'The Wall for Peace' and the Eiffel Tower in Paris for the International Day of Peace (© Prisma by Dukas Presseagentur GmbH/Alamy)

Fireworks during La Merce Festival in Barcelona, Spain (© Lucas Vallecillos/age fotostock)

Equinox at the Temple of Kukulcan in Chichen Itza, Mexico (© Somatuscani/Getty Images Plus)

A mountain gorilla eating in a tree in the Bwindi Impenetrable National Park, Uganda (© Robert Haasmann/Minden Pictures)

Arctic surfing trip in the Lofoten Islands, Norway (© Nicolás Pina/Tandem Stills + Motion)

The Pando, Fishlake National Forest, Utah, USA (© Don Paulson/Danita Delimont)

Sunset over Castildetierra, in the Natural Park of Bardenas Reales, Navarre, Spain (© Inigofotografia/iStock/Getty Images Plus)

Blooming jacaranda trees in New Farm Park, Brisbane, Australia (© Walter Bibikow/Danita Delimont)

Autumnal landscape near the town of Clavijo in Spain's Rioja district (© Olimpio Fantuz/eStock Photo)

An aerial view of Daxing International Airport in Beijing, China (© Xinhua/Alamy)

Coffee cherries in Quindío, Colombia (© The Colombian Way Ltda/Getty Images)