A solar-powered aircraft successfully completed the first fuel-free flight around the world, returning to Abu Dhabi after a 16-month voyage and demonstrating the potential of renewable energy.
The plane, Solar Impulse 2, touched down in the United Arab Emirates capital just after midnight local time (4am Irish time).
It first took off from Abu Dhabi on 9 March 2015, beginning a landmark journey of about 40,000km around the globe and nearly 500 hours of flying.
Unfavourable weather at times hindered smooth flying, causing the plane to be grounded for months in some countries.
Swiss explorers Bertrand Piccard & André Borschberg, Solar Impulse founders and pilots, took turns piloting the aircraft with a wingspan larger than a Boeing 747 and weighing only as much as a family car.
The Swiss team is campaigning to bolster support for clean energy.
Mr Piccard, who landed the plane in Abu Dhabi, said Solar Impulse was an achievement in the history of energy.
"We have flown one after the other in the cockpit with Andre, 40,000km without fuel, and now the demonstration is done.
"It means that the rest of the world has to take it further. We have to use these technologies. We have to stop listening to people who are afraid of changing their way of thinking. Solutions exist. They are profitable," said Mr Piccard.
The propeller-driven aircraft's four engines are powered exclusively by energy collected by more than 17,000 solar cells built into the plane's wings.
Excess energy is stored in four batteries during daylight hours to keep the plane flying after dark.
Over its entire mission, Solar Impulse 2 cruised at altitudes of up to 9,000 metres and at an average speed of between 45-90 km/h.
The plane had 16 stopovers along the way including in Oman, India, Myanmar, China, Japan, the United States, Spain and Egypt.
Abu Dhabi's green energy firm Masdar is the official host partner of Solar Impulse 2.
Oil-rich Abu Dhabi is investing billions in industry, tourism and renewables to diversify its economy away from oil.