As daunting as this and the eight previous legs of the trip have been, the tough part isn't over yet. While flying over the US will be a relative cakewalk (Solar Impulse 2 should reach New York by early June), the aircraft will then have to travel 3,566 miles to Europe. That's a straight 5 days in the air, folks. After that, the plane will complete its around-the-world mission by heading to Abu Dhabi.

This hasn't been the quickest adventure given that the aircraft took off back in March 2015. However, speed isn't really the point. Solar Impulse 2 and its namesake technology are meant to show that green energy can accomplish as spectacular a feat as flying across the planet. If the flight encourages anyone to embrace clean power, it accomplishes its goal.