A fin whale in the waters off the Azores (© Luis Quinta/Minden Pictures)

A red maple leaf in Mont-Saint-Bruno Conservation Park, Quebec, Canada (© Gilles Delisle/Jaynes Gallery/DanitaDelimont.com)

Cefalù on the Tyrrhenian coast of Sicily, Italy (© Tuul & Bruno Morandi/eStock Photo)

Close-up view of a Komondor (© Mike Segar/Reuters)

Policewomen from the United Nations Stabilisation Mission in Haiti attend a ceremony to mark International Women's Day in 2016 (© Hector Retamal/AFP/Getty Images)

Grapes on the vine in Mendoza, Argentina, for the National Grape Harvest Festival (© javarman3/iStock/Getty Images Plus)

Royal Highland Fusiliers playing the bagpipes on top of the Sydney Opera House (© James D Morgan/Shutterstock)

Wildflowers in bloom at Lost Dutchman State Park in Arizona, USA (© Tim Fitzharris/Minden Pictures)

Channels of the Rio Tinto in Spain (© Oscar Diez Martinez/Minden Pictures)

A view of Uranus taken from spacecraft Voyager 2 in 1986 (© NASA)

Circular agricultural fields in Morgan County, Colorado, USA (© Jim Wark/Getty Images)

At the Arch of Septimius Severus in the Roman Forum for the Ides of March (© Pietro Canali/eStock Photo)

Chital deer in misty grassland at dawn, Kanha National Park, India (© Pete Oxford/Minden Pictures)

Department of the Taoiseach lit up for the St Patrick's Festival in Dublin, Ireland (© David Soanes Photography/Getty Images)

Light from sunrise through a sea cave on the Isle of Skye, Scotland (© Luca Benini/PLM Collection/Offset)

Fireworks at the Plaza del Ayuntamiento for Las Fallas festival in Valencia, Spain (© Helena G.H/Shutterstock)

Crocus flowers (© Lorianne Ende/Getty Images)

A baobab grove near Bandia Wildlife Reserve in Senegal (© Frans Lanting/plainpicture)

Water wheel in the Tashkurgan Grassland, Tashkurgan Tajik Autonomous County, Xinjiang, China (© Ratnakorn Piyasirisorost/Getty Images)

From Nasa’s Terra satellite, an image of fallstreak holes in clouds over the southern United States (© NASA)

Shoreline near Tofino on Vancouver Island, British Columbia, Canada (© Robert Postma/plainpicture)

Athens, Greece, for Greek Independence Day (© junnyphoto/Getty Images)

Cherry blossoms over the Meguro River, Tokyo, Japan (© taketan/Getty Images)

The Llangattock Escarpment in the Brecon Beacons National Park, Powys, Wales (© Interfoto/DanitaDelimont.com)

A rufous-tailed hummingbird in Costa Rica (© Juan Carlos Vindas/Getty Images)

Auroville, India (© Vikram Ramakrishnan/Shutterstock)

New York City’s Empire State Building is seen lit up before Earth Hour in 2011 (© Eric Thayer/Reuters)

Bear cubs playing by a lake (© Sergey Ivanov/Getty)