Participants dressed in historical clothing ride high-wheel bicycles during a bicycle ballet event at Schloss Karlsruhe palace during the 2017 International Veteran Cycle Association (IVCA) rally to celebrate the 200th anniversary of the bicycle on May 27, 2017 in Karlsruhe, Germany. Karl Drais, a German inventor, built and tested the first bicycle, called the Draisine, that ran without pedals in 1817. (Photo by Alexander Scheuber/Getty Images)

A supercell thunderstorm develops, May 8, 2017 in Elbert County outside of Limon, Colorado. With funding from the National Science Foundation and other government grants, scientists and meteorologists from the Center for Severe Weather Research try to get close to supercell storms and tornadoes trying to better understand tornado structure and strength, how low-level winds affect and damage buildings, and to learn more about tornado formation and prediction. (Photo by Drew Angerer/Getty Images)

A reveller catches beer thrown from a balcony during the opening day or “Chupinazo” of the San Fermin Running of the Bulls fiesta on July 6, 2017 in Pamplona, Spain. The annual Fiesta de San Fermin, made famous by the 1926 novel of US writer Ernest Hemmingway entitled “The Sun Also Rises”, involves the daily running of the bulls through the historic heart of Pamplona to the bull ring. (Photo by Pablo Blazquez Dominguez/Getty Images)

Soldiers with the Afghan National Army (ANA) at an outpost in the Momand Valley on July 16, 2017 in Achin District, Afghanistan. The building was previously used as of a jail by the Islamic State of Iraq and Syria – Khorasan (ISIS-K) and was taken by Afghan Commandos nine days prior. Operations are currently underway to remove ISIS fighters from Nangarhar Province in Eastern Afghanistan. (Photo by Andrew Renneisen/Getty Images)

A parishioner of the St. Joseph the Worker Parish in Nairobi's Kangemi slum carries the vestments to be worn by Pope Francis during his visit to Kenya on November 24, 2015 in Kenya. Pope Francis makes his first visit to Kenya on a five day African tour that is scheduled to include Uganda and the Central African Republic. Africa is recognised as being crucial to the future of the Catholic Church with the continent's Catholic numbers growing faster than anywhere else in the world. (Photo by Nichole Sobecki/Getty Images)

A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. Image taken by NASA's Hubble Space Telescope. Released September 24, 2015. (Photo by Reuters/NASA/ESA/Hubble Heritage Team)

Indian artist Sudarsan Pattnaik works on a sand sculpture depicting drowned Syrian boy Aylan Kurdi at Puri beach, some 65 kilometers away from Bhubaneswar, on September 4, 2015. Charities helping refugees saw a surge in donations on September 4 across Europe as people shocked by the heart-rending images of a drowned Syrian boy on a Turkish beach dug deep to help out. The photos of the lifeless body of three-year-old Aylan Kurdi, lying on a beach in Bodrum, Turkey, have triggered a wave of emotion across the continent, despite deep divisions among European governments on how to deal with the crisis. (Photo by Asit Kumar/AFP Photo)

Female Naval Academy plebes perform push ups with a twelve foot log on top of them during the annual Sea Trials May 17, 2016 at the Naval Academy in Annapolis, Maryland. The Naval Academy freshman class endures 14 hours of rigorous physical and mental challenges during the annual Sea Trials training exercise as part of the culmination of their freshman year at the academy. (Photo by Win McNamee/Getty Images)