Yak near Yamdrok lake, Tibet. It is a long-haired bovinae found throughout the Himalayan region of south Central Asia, the Tibetan Plateau and as far north as Mongolia and Russia. The Tibetan economy is dominated by subsistence agriculture. Due to limited arable land, the primary occupation of the Tibetan Plateau is raising livestock, such as sheep, cattle, goats, camels, yaks, dzo, and horses. The Tibetan yak is an integral part of Tibetan life. (Photo by Dennis Jarvis)

Tech. Sgt. Milo Hinson, 3rd Combat Camera Squadron, uses a flashlight while shooting a Berretta 9mm during the night-fire portion of Advance Weapons, Tactics and Techniques training in San Antonio. During night-fire training, airmen learn how to tactically illuminate targets with flashlights and practice using night vision goggles. (Photo by Staff Sgt. Jonathan Snyder/U.S. Air Force). 2011

“Pearl Harbor, known to Hawaiians as Puʻuloa, is a lagoon harbor on the island of Oʻahu, Hawaiʻi, west of Honolulu. Much of the harbor and surrounding lands is a United States Navy deep-water naval base. It is also the headquarters of the U.S. Pacific Fleet. The attack on Pearl Harbor by the Empire of Japan on December 7, 1941, brought the United States into World War II”. – Wikipedia

Photo: Women fire fighters directing a hose after the Japanese attack on the US naval base at Pearl Harbour (Pearl Harbor). (Photo by Three Lions)

Henry Frayne of Australia shows his ability to triple jump the lenghth of more than two Formula 1 cars during a press conference at Albert Park on February 29, 2012 in Melbourne, Australia. (Photo by Robert Prezioso/Getty Images)

Aviator Frantisek Hadrava moves Vampira, an ultralight plane based on the U.S.-design of light planes called Mini-Max, out of a garage in the village of Zdikov, Czech Republic, August 23, 2016. Frantisek thought driving to work for 14 minutes was too much, so he built an plane to cut the commute by half. (Photo by David W. Cerny/Reuters)

In northwest Russia, in a small village called Alekhovshchina, Nadia Sablin's aunts spend the warmer months together in the family home and live as the family has always lived, chopping wood to heat the house and making their own clothes. Sablin's book of photographs, “Aunties: The Seven Summers of Alevtina and Ludmila”, is published by Duke University Press. Here: “Two-Handed Saw, 2014”. (Photo by Nadia Sablin)

A cat and a seagull feeding on a street in Heybeliada, the second largest of the Prince Islands in the Sea of Marmara, near Istanbul, Turkey on February 01, 2017. (Photo by Sebnem Coskun/Anadolu Agency/Getty Images)

The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)