In the penultimate stage of an historic round-the-world tour, Solar Impulse 2 has landed in Cairo. The plane, powered purely by the sun’s energy, will complete the 16-month journey in Abu Dhabi in the United Arab Emirates. BREAKING andreborschberg has landed in #Cairo after 2 days of flight & a flyover of the #Pyramids! #futureisclean pic.twitter.com/HD4J5XOHH5—…