(3 of 5)
This common condition, Menzel believes, is responsible for many of the saucer sightings (see diagram). The warm air overhead turns downward the light from bright objects, such as street lights or auto headlamps. If the "interface" is too turbulent, it can form no visible image, but if it is just steady enough, it will create bright images that seem to sweep rapidly across the dark sky. This is the explanation, says Menzel, for the famous "Lubbock Lights,"* which have been taken for interplanetary space ships flying in formation. They may be the images of a string of lights at a distance, or they may be reduplicated images of a single very bright light.
From an Airplane, Dimly. Other inversions produce other kinds of saucers. Sometimes a warm layer hangs several thousand feet up (see diagram). Often the layer contains dust, which increases its power to divert light. If an airplane is flying just above this layer, the pilot may see the dim displaced image of the sun, the moon or a high, brightly lighted cloud. The image will appear below him; it may be distorted, magnified, or in rapid motion. If the inversion has waves in its surface (common near mountain ridge's), the pilot may see a line of bright objects in rapid motion. Menzel believes that this is what Pilot Kenneth Arnold saw in 1947 when he reported the first flying saucers over a high ridge near Mt. Rainier.
If the plane is flying just below the inversion, the pilot may see distorted images from light sources below it. Such images can also be seen from the ground when the inversion is low enough. They may look like single moving objects or they may be lines of bright points shooting across the sky.
A special kind of flying saucer, says Menzel, has been seen four times, just after the launching of a big "sky hook" balloon. They appear as roundish objects, apparently at a great height. He believes that they are caused by the balloon itself when it rises through a thin layer of warm air at a thousand feet or so (see diagram). As it rises, it punches a hole in the layer. Cold air flows in, forming a blob of denser air that acts as an imperfect lens. Observers on the ground see a small moving image of the balloon above. The same effect can be produced, says Menzel, by holding a strong spectacle lens at arm's length toward a light.
Foo-Fighters. Another saucerlike object is the "foo-fighter": a bright spot of light which seemed to chase night-flying airplanes during World War II. Menzel believes that foo-fighters are really light (from the moon, from a plane's exhaust or from some other source) that is turned into the pilot's eye by strong eddies of air near a damaged wing. The moon disks that he saw himself were probably a sort of foo-nghter.
The only flying saucers which Menzel's theory does not explain are the green fireballs that have been reported with extraordinary frequency in the Southwest. But Menzel does not take them very seriously. In clear-aired New Mexico and Arizona, he says, meteors are seen oftener than in cloudier places. According to Menzel's colleague, Meteor Expert Fred Whipple, they often look green because of vaporized magnesium from their stony material.