U.S. Air Force pilots with the Thunderbirds perform the calypso pass maneuver in F-16 Fighting Falcon aircraft during a practice session prior to the Gunfighter Skies air show at Mountain Home Air Force Base, Idaho, September 19 and released September 24, 2014. (Photo by Tech. Sgt. Manuel J. Martinez/Reuters/US Air Force)

Some women doing yoga pose on the hammocks during the Anti-Gravity yoga class at Svarga e-Motion Sanctuary at Dharmawangsa Square, Jakarta, Saturday, April 18, 2015. Anti-Gravity Yoga or “aerial yoga”, is a new type of yoga, originating in New York but now being practised in several countries, which combines the traditional yoga poses, pilates and dance with the use of a hammock. (Photo by Jurnasyanto Sukarno/JG Photo)

Aerial acrobat Schindler, notorious for his foolhardy stunts, practising one of his tricks listing out of the vertical, from a Klemp plane piloted by Richard Perlia. (Photo by General Photographic Agency/Getty Images). Circa 1927

Members of the public admire trees displaying their autumn colours at the Royal Horticultural Society Garden Wisley on October 26, 2011 in Wisley, England. Many deciduous trees have now changed colour as they begin to shed their leaves for Autumn. An extended period of leaf colour change has come about this year due to a warm, dry Spring prompting an early growth spurt and a premature colour change. (Photo by Oli Scarff/Getty Images)

The sun streaks through the fall foliage at sunrise along the Potomac River in Arlington, Va., Wednesday, November 4, 2015 on a warm fall day in the nation's Capitol area. (Photo by J. David Ake/AP Photo)

Tommy Lindsey holds an enormous maple leaf that he found in Mount Vernon, Wash., October 28, 2013. Lindsey was walking with his family when he picked up the leaf that is more than two feet from stem to tip and more than 21 inches wide. (Photo by Frank Varga/The Skagit Valley Herald)

The sun shines on trees that are displaying their autumn colours surrounding Palladian bridge and the lakeside Pantheon at the National Trust's Stourhead on November 3, 2010 near Warminster, England. (Photo by Matt Cardy/Getty Images)

A soldier poses with a Hythe Mk III Gun Camera during training activities at Ellington Field, Houston, Texas in April of 1918. The Mk III, built to match the size, handling, and weight of a Lewis Gun, was used to train aerial gunners, recording a photograph when the trigger was pulled, for later review, when an instructor could coach trainees on better aiming strategies. (Photo by Harry Kidd/WWI Army Signal Corps Photograph Collection via The Atlantic)