An Iranian woman gestures as she celebrates in the streets following a nuclear deal with major powers, in Tehran July 14, 2015. Overcoming decades of hostility, Iran, the United States, and five other world powers struck a historic accord Tuesday to check Tehran's nuclear efforts short of building a bomb. The agreement could give Iran access to billions in frozen assets and oil revenue, stave off more U.S. military action in the Middle East and reshape the tumultuous region. (Photo by Reuters/TIMA)

A British Airways passenger plane flies in front of the moon above London, Britain, May 3, 2018. (Photo by Toby Melville/Reuters)

Photographer Brian Finke spent nearly two years traversing the friendly skies, following the life of flight attendants in the air and on the ground, from Delta and Hawaiian Air, to Hooters Air, Southwest, Air France, British Airways, Air Asia, and dozens more. His images of flight attendants waving, applying makeup and deboarding plans while smiling appear as if they were ripped from an advertisement in a glossy magazine. Here: Tiger Airways, Singapore, 2006. (Photo by Brian Finke/The Washington Post)

Eurocopter's X³ high-speed hybrid helicopter demonstrator performs, September 6, 2010. The Eurocopter X³ (X-Cubed) is an experimental high-speed compound helicopter developed by Eurocopter (now Airbus Helicopters). A technology demonstration platform for Eurocopter “high-speed, long-range hybrid helicopter” or H³ concept, the X³ achieved 255 knots in level flight on 7 June 2013, setting an unofficial speed record for a helicopter. (Photo by Reuters/HO/Eurocopter/Penna)

Michael Read, director of Flight Operations from New Zealand-based Martin Aircraft Company, flies a Martin Jetpack during a demonstration at a water park in Shenzhen, China December 6, 2015. KuangChi Science Ltd, a Hong Kong-listed Chinese company and investor of Martin Aircraft, will sell the flying machine in mainland China for 1.6 million yuan ($249,902), according to the company. (Photo by Bobby Yip/Reuters)

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)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

The Spanish photographer Xavi Bou digitally combines sequential pictures of birds to create a single image, or chronophotograph, that reveals the shapes of their flight paths against Catalonian skies. His work shows the variety and beauty to be found in the daily activities of the local birds, including spiralling storks, swooping starlings and giddy swifts. Here: European herring gulls at Llobregat Delta. (Photo by Xavi Bou/Rex Features/Shutterstock)