The Solar Impulse 2 left southern Spain today on its way to Egypt for the penultimate leg of the solar-powered airplane's landmark round-the-world journey.

The experimental aircraft took off from Seville at 6:20 am for a flight that should last about 50 hours and will take it over the Mediterranean Sea. Swiss national Andre Borschberg was at the controls for the journey that will pass through through Algerian, Tunisian, Italian, Maltese and Greek airspace.

Solar Impulse is to land in Cairo yesterday. The plane, which is no heavier than a car but has the wingspan of a Boeing 747, will then set out for Abu Dhabi on the final leg of its voyage. It took off from the United Arab Emirates capital on March 9, 2015 with the aim of promoting clean, renewable energy.

Solar Impulse is being flown on its 35,400-kilometre (22,000-mile) trip around the world in stages, with Borschberg and his Swiss compatriot Bertrand Piccard taking turns at the controls of the single-seat plane.