Andrey Karr from Western Riders Slacklines at sunset above big waves in Nazare, Portugal on December 27, 2017. (Photo by Aidan Williams/National Geographic Travel Photographer of the Year Contest)

Revellers take part in an annual block party before Carnival in downtown Rio de Janeiro, Brazil, January 16, 2016. The Rio de Janeiro Carnival will be held from February 5 to February 9. (Photo by Pilar Olivares/Reuters)

An Emperor Tamarin monkey, native to the Amazon rainforest, experiences its new home in the living rainforest enclosure at ZSL London Zoo on March 25, 2010 in London, England. Entitled “Rainforest Life” the large temperature and humidity controlled bio-dome is home to free-roaming monkeys, sloths, tree anteaters and tropical birds. The exhibit, which is opening in the International Year of Biodiversity, will be open to the public from March 27, 2010. (Photo by Oli Scarff/Getty Images)

A palomino horse's mane is seen against the sky at Spancil Hill horse fair in Spancil Hill, Ireland June 23, 2018. (Photo by Clodagh Kilcoyne/Reuters)

Horses are spooked as the Woolsey Fire moves through the property on Cornell Road near Paramount Ranch on November 9, 2018 inAgoura Hills, California. About 75,000 homes have been evacuated in Los Angeles and Ventura counties due to two fires in the region. (Photo by Matthew Simmons/Getty Images)

The 26th annual National Geographic Traveler Photo Contest is now accepting submissions. Official categories include: “Travel Portraits”, “Outdoor Scenes”, “Sense of Place” and “Spontaneous Moments”. The contest is accepting entries until June 30. Photo: “Forest lights”. Aurora Borealis over the forest of the Pyhae Luosto National Park, Finland. (Photo and caption by Nicholas Roemmelt/National Geographic Traveler Photo Contest)

An ice covered entrance door to the international gene bank Svalbard Global Seed Vault (SGSV) near Longyearbyen on Spitsbergen, Norway, October 20, 2015. Two consignments of crop seeds will be deposited next year in a “doomsday vault” built in an Arctic mountainside to safeguard global supplies. The vault, which opened on the Svalbard archipelago in 2008, is designed to protect crop seeds, such as beans, rice and wheat against the worst cataclysms of nuclear war or disease. (Photo by Anna Filipova/Reuters)

“The Curiosity Mars rover has imaged a small metallic-looking protuberance on a rock. Visible (in the image below the green lines point to it), the protuberance appears to have a high albedo and even projects a shadow on the rock below...”