Setting off from New York at 2:30 AM on June 20, 2016, pilot Bertrand Piccard spent a total of 71 hours and 8 minutes in the air, flying at 28,000 feet and covering a distance of 4,203 miles before landing in Seville, Spain, at 7:38 AM local time.

"Crossing the Atlantic ocean is challenging. The plane is sensitive to turbulence, so we have to plan the route carefully and identify the perfect weather window," Alexandra Gindroz, head of Solar Impulse's media relations, told me over the phone.

She stressed how it was important for the plane to navigate between weather fronts to stay in calm weather. Fortunately, the weather, said Gindroz, had been stable during the arduous flight over the Atlantic, with a good tail wind speeding up the plane's journey, and spatterings of cloud—that could block the sun from powering the craft—luckily located either in front or behind the solar plane.