 Another theory states that most are natural phenomena such as lenticular clouds and balloons, which appear disc-like in some lighting conditions.A third theory puts all saucer sightings down to a form of mass hysteria.Arnold described the craft he saw as saucer-like but not perfectly round (he described them as thin, flat, rounded in front but chopped in back and coming to a point), but the image of the circular saucer was fixed in the public consciousness.