Enhanced-color composite of the Caloris Basin, Mercury (© NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Aerial view of the theatre at the ancient city of Hierapolis, adjacent to Pamukkale, Turkey (© Amazing Aerial Agency/Offset by Shutterstock)

Dove Lake, Hobart, Tasmania (© www.JamesPhotography.com.au/Getty Images)

Gypsum sand dunes, White Sands National Park, New Mexico, USA (© Grant Kaye/Cavan Images)

Great Point Light on Nantucket Island, Massachusetts, USA (© Cate Brown/Cavan Images)

Tolbachik volcanic complex on the Kamchatka Peninsula, Russia (© Egor Vlasov/Shutterstock)

Grey seal pup resting on a beach in Blakeney National Nature Reserve, England (© Kevin Sawford/Getty Images)

Grey seal pup resting on a beach in Blakeney National Nature Reserve, England (© Kevin Sawford/Getty Images)

The bell tower in Lake Reschen in South Tyrol, Italy (© Scacciamosche/Getty Images)

American Basin in southern Colorado's San Juan Mountains, USA (© Blaine Harrington III/Alamy)

The Hoh Rainforest in Olympic National Park, Washington state, USA (© Jorge Romano/Offset by Shutterstock)

Milky Way over the Southern Ocean, Australia (© John White Photos/Getty Images)

The Panthéon in Paris, France (© manjik/Shutterstock)

The flooded crypt at Winchester Cathedral, Hampshire, England (© Oliver Hoffmann/Alamy)

North Pacific humpback whale breaching in Frederick Sound, Alaska (© Tony Wu/Minden Pictures)

Happy hot air balloon (© Leonsbox/Getty Images Plus)

Nine-spotted moth in Switzerland (© Thomas Marent/Minden Pictures)

Nine-spotted moth in Switzerland (© Thomas Marent/Minden Pictures)

Earthrise across Mare Smythii on the moon (© Image Science and Analysis Laboratory, NASA-Johnson Space Center)

The town of Dinant and the River Meuse in Namur, Belgium (© Kadagan/Shutterstock)

Blue wildebeest herd migrating at sunset, Maasai Mara Game Reserve, Kenya (© Denis-Huot/Minden Pictures)

Cradle Mountain, Tasmania, on a very cold morning (© Steve Daggar Photography/Getty Images)

Elephants at Kapama Private Game Reserve in South Africa (© Simon Eeman/Getty Images)

Disko Bay, Ilulissat, Greenland (© Kertu/Shutterstock)

Tamul waterfall in the state of San Luis Potosí, Mexico (© Robert Harding World Imagery/Offset by Shutterstock)

A numbat (Myrmecobius fasciatus) in Australia (© FRANS LANTING, MINT IMAGES/SCIENCE PHOTO LIBRARY)

Hamelin Pool Marine Nature Reserve in Western Australia (© Abstract Aerial Art/Getty Images)

Kalsoy Island, part of the Faroe Islands (© Swen Stroop/Getty Images Plus)

Hamerkop standing on a hippo, Mana Pools National Park, Zimbabwe (© David Fettes/Getty Images)

A lava flow hits water to create an explosion as a tourist boat passes, Hawaii Volcanoes National Park, USA (© Patrick Kelley/Getty Images)

Lightning storm in the Tortolita Mountain foothills, north of Tucson, Arizona, USA (© Jack Dykinga/Minden Pictures)