The first solar-powered plane to circle the world took off from Cairo on Sunday for Abu Dhabi, in the final leg of its journey.

Swiss pilot Bertrand Piccard was behind the controls of Solar Impulse 2, which can fly for days on only energy from the sun.
"It's a project for energy, for a better world," Piccard told journalists before taking off.
Pilots Piccard and Swiss entrepreneur Andre Borschberg have taken turns flying the plane on its 35,000 kilometre (22,000-mile) trip around the world.
Borschberg piloted the flight's Pacific stage, a 8,924 kilometre flight between Nagoya, Japan, and Hawaii.
Solar Impulse 2 arrived in Cairo after a two-day flight from Spain, finishing the 3,745 kilometre journey with an average speed of 76.7 kilometres an hour.
It had earlier landed in Seville after completing the first solo transatlantic flight powered only by the sun.
The single-seat aircraft, no heavier than a car but with the wingspan of a Boeing 747, is clad in 17,000 solar cells. During night-time flights it runs on battery-stored power.
It typically travels at a mere 30 miles (48 kilometres) per hour, although its flight speed can double when exposed to full sunlight.