Boeing B-29 (#10) from the 24th Bomb Squadron, 6th Bomb Group after an emergency landing at Iwo Jima on April 24,1945. (Photo by U.S. Air Force)

A tourist poses for a picture with the Sphinx at the Pyramids of Giza in Cairo, Egypt, on October 19, 2011. (Reuters/Jamal Saidi)

President Barack Obama with does the tango with a dancer during the State Dinner at the Centro Cultural Kirchner, Wednesday, March 23, 2016, in Buenos Aires, Argentina. (Photo by Pablo Martinez Monsivais/AP Photo)

Model Lily Donaldson flashes the peace sign as she leaves Victoria's Secret Fashion Show China casting in New York City on August 22, 2017. (Photo by Christopher Peterson/Splash News and Pictures)

Students hold their weapons before the swearing in ceremony for the military students, in Bucharest, Romania, Wednesday, October 25, 2017. The Romanian Army is proudly celebrating their Army Day and marking 100-years since the landmark battle of Marasesti, a key World War I battle in 1917 when Romanian and Russian soldiers defeated German troops, halting a German offensive. (Photo by Vadim Ghirda/AP Photo)

In this April 4, 2017 photo keeper German Alonso straps a leg prothesis to on the left leg of secretarybird Soeckchen (Sagittarius seprentarius) at the bird park in Walsrode, northern Germany. The prothesis was made in a 3D-printer after his left leg was amputated. (Photo by Philipp Schulze/DPA via AP Photo)

An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) emerges from a cloud created when it broke the sound barrier in the skies over the Pacific Ocean, July 7, 1999. (Photo by John Gay/US Navy)

Members of the King's Troop Royal Horse Artillery fire a 41 gun salute in Hyde Park to mark the 60 anniversary of the accession of Her Majesty Queen Elizabeth II on February 6, 2012 in London, England. (Photo by Oli Scarff/Getty Images)