A nesting colony of king penguins in South Georgia, Antarctica (© Ralph Lee Hopkins/National Geographic/Offset)

Rainbow at Victoria Falls in Zambia (© Dietmar Temps/Shutterstock)

Pronghorn buck (© Donald M. Jones/Minden Pictures)

Green tree frog and purple water lily, Lake Kissimmee, Florida, USA (© Joanne Williams/Danita Delimont)

Cherry blossoms and Himeji Castle in Himeji, Japan (© Tororo/Getty Images)

Daffodils in Dora’s Field, Rydal, Lake District (© Simon Whaley Landscapes/Alamy Stock Photo)

The April full moon, or pink moon, rises over St Michael's Mount, Cornwall (© Simon Maycock/Alamy Live News)

A pod of narwhals near Baffin Island, Nunavut, Canada (© Eric Baccega/Minden Pictures)

A Kermode bear cub huddling with its sibling in Canada's Great Bear Rainforest, British Columbia (© Ian McAllister/Offset)

Ancient Roman gold mining site of Las Médulas, León, Spain (© DEEPOL by plainpicture/David Santiago Garcia)

Temples of Wat Chaloem Phra Kiat Phrachomklao Rachanusorn in Lampang province, Thailand (© pa_YON/Getty Images)

Pantropical spotted dolphins off the coast of Ixtapa, Mexico (© Christian Vizl/Tandem Stills + Motion)

Pantropical spotted dolphins off the coast of Ixtapa, Mexico (© Christian Vizl/Tandem Stills + Motion)

Sipapu Bridge in Natural Bridges National Monument, Utah, USA (© Fyletto/Getty Images)

Bluebells in Micheldever Wood, Hampshire (© Hursley/Getty Images Plus)

Vernal Fall in Yosemite National Park, California, USA (© elvistudio/Shutterstock)

Milky Way over Neist Point Lighthouse, Isle of Skye, Scotland (© Shaiith/Getty Images)

Keukenhof in Lisse, Netherlands (© Jim Zuckerman/Getty Images)

The Grand Prismatic Spring in Yellowstone National Park, Wyoming, USA (© Martin Rügner/DEEPOL by plainpicture)

Te Matua Ngahere, a giant kauri tree growing in Waipoua Forest, Northland, New Zealand (© Kim Westerskov/Getty Images)

Monument to St George and the Dragon at sunset, Moscow, Russia (© Protasov AN/Shutterstock)

The Large Magellanic Cloud, photographed by the Hubble Space Telescope (© ESA/Hubble/NASA)

Southern rockhopper penguins on the Falkland Islands (© Heike Odermatt/Minden Pictures)

Sunset at Ruby Beach in Olympic National Park, Washington state, USA (© Adam Mowery/Tandem Stills + Motion)

Sunset at Ruby Beach in Olympic National Park, Washington state (© Adam Mowery/Tandem Stills + Motion)

Salisbury Cathedral with grazing flock of sheep, Wiltshire (© Slawek Staszczuk Photo/Alamy)

Aerial view of Santorini island, Greece (© Amazing Aerial Agency/Offset)

Arctic redpoll nest in Lapland, Finland (© Maximilian Buzun/Alamy)

Sunrise at Llyn Padarn at Llanberis, Snowdonia National Park (© Helen Hotson/Alamy Stock Photo)