Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

A woman walks through flood water during heavy downpour at a street in Genoa, Italy, 10 October 2014. At least one person died due to flooding after heavy rains caused the Bisagno river, which runs through Genoa city to overflow. Part of the city was in black-out with flooded streets and parked cars dragged away by the water's force. (Photo by Luca Zennaro/EPA)

Huge waves hit the promenade at Whitley Bay, North Tyneside, England late Monday afternoon, March 11, 2024, with some people braving a walk along the seafront. (Photo by Ian Sproat/Picture Exclusive)

A motoring enthusiast takes part in the “Race The Waves” classic car and motorcycle meet at the beach in Bridlington, Britain, on May 12, 2024. (Photo by Lee Smith/Reuters)

A mandarin duck swims through reflections of spring growth and blossom on a pond in Richmond Park in London, Britain on April 28, 2025. (Photo by Toby Melville/Reuters)

One of the busiest areas in Birmingham, United Kingdom last night was Ludgate Hill in the city's Jewellery Quarter. Brits enjoying the hottest August day for almost 20 years spilled out of packed pubs on August 7, 2020 after sunbathing on beaches around the country as the mercury rose to 36.4C. (Photo by SnapperSK/The Sun)

A villa privately built on the rooftop of a residential building in downtown Beijing has prompted complaints from neighbours living below. Professor Zhang, the villa owner, has been instructed to tear down the illegal building, according to the property managers. (Photo by Mark Ralston/AFP Photo)

“NASA's Pathfinder, Pathfinder Plus, Centurion and Helios Prototype were an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as “atmospheric satellites”, to perform atmospheric research tasks as well as serve as communications platforms”. – Wikipedia

Photo: The solar-electric Helios Prototype flying wing is flies over the Hawaiian islands of Niihau and Lehua during the first solar-powered test flight July 14, 2001 from the U.S. Navy's Pacific Missile Range Facility on Kauai, HI. The 18-hour flight was a functional checkout of the aircraft's systems and performance in preparation for an attempt to reach sustained flight at 100,000 feet altitude later in the summer. (Photo Courtesy of NASA/Getty Images)