A glass skywalk in Wanyuan, Sichuan province, built along the side of a cliff, is the highest such skywalk anywhere in China on January 31, 2017. Some visitors have been proven to be terrified by the experience had to brace against the wall in fear. (Photo by Chinanew.com/AsiaWire)

Women stage a topless protest in Buenos Aires, Argentina on February 7, 2017. Activists take to streets of downtown after three women had been topless sunbathing on Necochea, near Buenos Aires, when they were approached by officers that told to cover their breasts. The sunbathers and officers argue, with the girls insisting going topless is not illegal, but the police insist they are offending the local culture. This protest is in support of the three women of Necochea. (Photo by Claudio Santisteban/ZUMA Wire/Rex Features/Shutterstock)

A model falls over on the runway in a design by Victoria Bliss during the Project NextGen show at Mercedes-Benz Fashion Week Resort 18 Collections at Carriageworks on May 16, 2017 in Sydney, Australia. (Photo by Stefan Gosatti/Getty Images)

Festival goers having fun at the Balaton Sound music festival in Zamardi next to the Lake of Balaton, 110 km (68 miles) west of Budapest, July 6, 2017. (Photo by Zsolt Furesz)

Bangladeshi Muslim devotees arrive in an over-crowded train to attend the final day of an Islamic congregations' first phase in Tongi, 20 kilometers (13 miles) north of Dhaka, Bangladesh, Sunday, January 10, 2016. The second phase of the annual event, one of the world's largest congregations of Muslims is scheduled to begin Friday. (Photo by A.M. Ahad/AP Photo)

England fan celebrates on top of an ambulance after England' s win over Sweden in the Russia 2018 World Cup quarter- final football match, in London on July 7, 2018. (Photo by Henry Nicholls/Reuters)

People walk past a sculpture entitled “Reunion” by artist Sam Jinks at a preview of the Melbourne Art Fair in Melbourne on August 1, 2018. The sculpture is made of silicone, pigment, resin and human hair. (Photo by William West/AFP Photo)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)