Shortly after midnight in early May, a strange aircraft approached Phoenix’s Sky Harbor International Airport. It had the wingspan of a jumbo jet but flew at only about 40 miles per hour; 16 bright, bluish-white lights shone along the leading edge of its spindly wings. Concerned Phoenicians called the police to report an alien landing.
Sky Harbor’s air traffic control explained to Phoenix police that the ostensible UFO was really a solar-powered airplane: the Solar Impulse, an experimental aircraft completing the first, 19-hour leg of a flight across the United States. Then the police asked how it could fly at night if it’s solar-powered. (Batteries.)