Rooftops of solar powered houses are pictured in Ota, 80 km northwest of Tokyo in this October 28, 2008 file photo. One by one, Japan is turning off the lights at the giant oil-fired power plants that propelled it to the ranks of the world's top industrialised nations. With nuclear power in the doldrums after the Fukushima disaster, it's solar energy that is becoming the alternative. Solar power is set to become profitable in Japan as early as this quarter, according to the Japan Renewable Energy Foundation (JREF), freeing it from the need for government subsidies and making it the last of the G7 economies where the technology has become economically viable. (Photo by Yuriko Nakao/Reuters)

A Hong Kong Vegetarian Society activists lies on a giant plate alongside oversized peas, carrots and cutlery during a protest rally in the tourist district of Tsim Sha Tsui, Hong Kong, China, 23 December 2015. The activists urged passers-by to extend the holiday spirit to animals and to give thoughts to the cruelty inflicted on animals in meat productions. (Photo by Jerome Favre/EPA)

Wednesday March 8 marks International Women's Day, with festivals, concerts and exhibitions among the numerous events planned around the world to celebrate the achievements of women in society. The annual event has been held since the early 1900s and traditionally promotes a different theme each year, with this year's edition calling on people to #BeBoldForChange and push for a more gender-inclusive working world. Reuters photographers have been speaking with women in a range of professions around the world about their experiences of gender inequality. Here: Yolaina Chavez Talavera, 31, a firefighter, poses for a photograph in front of a truck at a fire station in Managua, Nicaragua, February 22, 2017. (Photo by Oswaldo Rivas/Reuters)

“Igor Sikorsky (May 25, 1889 – October 26, 1972), born Igor Ivanovich Sikorsky was a Russian American pioneer of aviation in both helicopters and fixed-wing aircraft. He designed and flew the world's first multi-engine fixed-wing aircraft, the Russky Vityaz in 1913, and the first airliner, Ilya Muromets, in 1914. After immigrating to the United States in 1919, Sikorsky founded the Sikorsky Aircraft Corporation in 1923, and developed the first of Pan American Airways' ocean-conquering flying boats in the 1930s. In 1939 Sikorsky designed and flew the Vought-Sikorsky VS-300, the first viable American helicopter, which pioneered the rotor configuration used by most helicopters today. Sikorsky would modify the design into the Sikorsky R-4, which became the world's first mass-produced helicopter in 1942”. – Wikipedia

Photo: Westland Sikorsky H-5's, used by British European Airways Helicopters, which fly between London and Birmingham. The Sikorsky H-5, (aka R-5, S-51, HO3S-1, or Horse) (R-5 until 1948; company designation VS-327) is a helicopter built by Sikorsky Aircraft Corporation, formerly used by the United States Air Force, and its predecessor, the United States Army Air Forces, as well as the United States Navy and United States Coast Guard (with the designations HO2S and HO3S). (Photo by Harrison /Topical Press Agency/Getty Images). 22nd May 1951

In this October 15, 2014 file photo, Katsu Nakamura, sky division manager for Yamaha USA, moves the RMax unmanned helicopter into position before a demonstration of its aerial application capabilities at the University of California, Davis' Oakville Station test vineyard in Oakville, Calif. Researchers at UC Davis have been studying the effectiveness of the drone's ability for spraying pest control and nutritional materials on the test vineyard in California's Napa Valley. (Photo by Rich Pedroncelli/AP Photo)

North Korean leader Kim Jong Un is hugged by children during his visit to Samjiyon County in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang November 28, 2016. (Photo by Reuters/KCNA)

This lemur looks like he is channelling the spirit of Buddha – as he sits meditating. Sitting with his legs crossed, the lemur clasps his thumb and fore finger together with outstretched arms – just like the spiritual teacher. And amateur snapper Sebastien Degardin, 32, was on hand to capture the bizarre moment the animal searched for enlightenment on film. Sebastien, who moved from his native Belgium to Finchley, North London, said: “I was gobsmacked when I saw this lemur meditating”. (Photo by Sebastien Degardin/Caters News)

“Don't Leave Any Food On Your Plate”. The giraffes at Nairobi's Giraffe Manor are totally at home with humans. They will eat out of your hand, or even off your plate. Photo location: Giraffe Manor, Nairobi, Kenya. (Photo and caption by Gavin Werbeloff/National Geographic Photo Contest)