Armed Syrian Turkmen villagers are seen near the northern Syrian village of Yamadi, near the Turkish-Syrian border, Syria, November 24, 2015. Turkey shot down a Russian warplane near the Syrian border on Tuesday saying it had repeatedly violated its air space, one of the most serious publicly acknowledged clashes between a NATO member country and Russia for half a century. (Photo by Reuters/Stringer)

Inside the Afar Triangle in Ethiopia’s Danakil desert, camel caravans are used to carry salt. For centuries, the essential mineral has been mined by the Afar people, known for their ability to withstand extremes. The terrain is rugged, travelers are scarce and so are motor vehicles, where the average annual temperature is the highest in the world, and can rise to 122 degrees Fahrenheit, 50 degrees Celsius. (Photo by Ziv Koren/Polaris)

McMurdo Station is a U.S. Antarctic research centre located on the southern tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the United States Antarctic Program, a branch of the National Science Foundation. The station is the largest community in Antarctica, capable of supporting up to 1,258 residents, and serves as the United States Antarctic science facility. All personnel and cargo going to or coming from Amundsen–Scott South Pole Station first pass through McMurdo.

Photographer Carlos Barria holds a print of a photograph he took in 2005, as he matches it up at the same location 10 years on, in Lafitte, south of New Orleans, United States, August 16, 2015. The print shows Tyler Teal cleaning up his home, September 14, 2005, after Hurricane Katrina struck. In 2005, Hurricane Katrina triggered floods that inundated New Orleans and killed more than 1,500 people as storm waters overwhelmed levees and broke through floodwalls. (Photo by Carlos Barria/Reuters)

Residents watch the ocean waves crash into the water front, after the passage of Hurricane Irma, in Cuba, Sunday, September 10, 2017. (Photo by Ramon Espinosa/AP Photo)

As a social experiment, journalist Esther Honig contacted Photoshop artists across the world and told them to make her beautiful, and they did. Honigh said she was surprised by how her image was altered, saying the process has greatly changed her perception of beauty. Photo: “Before & After” project: Greece. (Photo by Esther Honig)

Clutching a large paper bag and shading his eyes as he peers ahead, comic actor of the silent screen, Buster Keaton (1885–1966) arriving at Paris airport. (Photo by Keystone/Getty Images). 1st August 1947

A worker pauses for a sandwich, resting on a girder during the construction of a skycraper. (Photo by Hulton Archive/Getty Images). Circa 1930