Free Syrian Army fighters stand near an ambulance on the eastern edge of the northern Syrian town of al-Bab, Syria, February 27, 2017. (Photo by Khalil Ashawi/Reuters)

Enthusiasts gathered at Cad East in Snowdonia National Park, England to take pictures of F-15 Eagle fighters as they completed the Mach Loop, November 2017. (Photo by Caters News Agency)

Militant Islamist fighters take part in a military parade along the streets of Syria's northern Raqqa province June 30, 2014. The fighters held the parade to celebrate their declaration of an Islamic “caliphate” after the group captured territory in neighbouring Iraq, a monitoring service said. The Islamic State, an al Qaeda offshoot previously known as Islamic State in Iraq and the Levant (ISIL), posted pictures online on Sunday of people waving black flags from cars and holding guns in the air, the SITE monitoring service said. (Photo by Reuters/Stringer)

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)

Hemispheric color differences on Saturn's moon Rhea are apparent in this false-color view from NASA's Cassini spacecraft in this March 2, 2010 file photo. (Photo by Reuters/NASA/JPL/SSI)

Lady Gaga performs at Staples Center on August 11, 2010 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)

Space Shuttle Discovery is towed from the shuttle landing facility to the orbiter processing facility at Kennedy Space Center on April 20, 2010 in Cape Canaveral, Florida. Discovery's landing attempts at KSC were scrubbed yesterday due to unacceptable weather conditions. Discovery is returning from a successful mission to the International Space Station. (Photo by Matt Stroshane/Getty Images). CAPE CANAVERAL, FL – APRIL 20 2010

A gallery assistant for Sotheby's auction house admires a melchior of Chateau Cheval Blanc 2006 on February 12, 2010 in London, England. The melchior sized bottle, which is 18 litres in volume, is to be sold in Sotheby's sale of “Finest and Rarest Wines & Vintage Port” on February 17, 2010 in London and is expected to fetch up to 4,800 GBP. (Photo by Oli Scarff/Getty Images)