Solar Impulse 2 completes round-the-world trip on sun power alone    More than a year after it took off from Abu Dhabi, Solar Impulse 2 has completed its round-the-world trip. The solar-powered plane landed back again in Abu Dhabi last night, just over two days after    http://www.theverge.com/2016/7/26/12283128/solar-impulse-2-completes-round-the-world-trip-sun