The planets are wanderers. Each day they move to a new position among the constellations. Astronomers and navigators have learned the paths of the planets and the positions of the brightest fixed stars, but most of us, when we look up at the night sky and see a brilliant stranger among the familiar star groups, must cudgel our brains to account for it. According to our dispositions, we may consult a newspaper or telephone an observatory to find out the name of the intruder, or we may conclude that the unknown is an alien spacecraft. The planet Venus has been chased at least once by patrolmen in a squad car, has several times caused the scrambling of jet interceptors, and has been named the culprit in so many UFO mysteries that saucer enthusiasts somewhat cynically refer to it as “the whipping girl” of saucerdom. The brightest of the planets and the closest to earth, Venus never moves more than 45 degrees from the sun and thus is most often visible in our skies near sunrise or sunset, preceding or following the sun. The apparent size of the planet varies according to its distance from the earth and its phase. When it is farthest from the earth, the disk has a diameter of ten seconds; at its closest, the diameter has grown sixfold, to sixty-four seconds. The human eye and the ordinary camera see it as a brilliant white star. Being nearer the sun, Venus receives almost twice as much light from the sun as does the earth, and when at greatest brilliance, can be seen in the daytime sky. Viewed momentarily through rapidly moving cirrus clouds, it may seem to be racing across the sky like a flying saucer, but a longer look will reveal that the object is actually making very slow progress, like a planet[IV-4]. To the airman in the cockpit of a plane, the planet in the dawn sky can be a breathtaking sight. As one veteran pilot has described the experience, “Venus rose to signal me from the eastern horizon, so brilliant and inconsistent in color, changing at once from yellow to green to purple and then reversing the show, that I thought for a time it was another aircraft equipped with special lighting devices. But Venus steadied in time, proving its identity.”[IV-5]