SCIENCE NOTES Natural Explanation For Flying Saucers

Press, Volume XCIX, Issue 29189, 27 April 1960, Page 11

SCIENCE NOTES Natural Explanation For Flying Saucers

[By

RITCHIE CALDER)

thev do not exist whv 51 Ueve ln flyin £ saucers? If have sin ?hem? f ’ d ° S ° many people say they Y es > I believe in the ones we make the Hover l °o MS a story and are stroking to it, there has 5 a nataral investigated/ 01 m ° St ““K

For instance, some years ago in Ontario, there was a whole crop of flying saucers, testified to by apparently reliable witnesses. The explanation in that case was spiders’ webs! In a particular area, spiders made large webs on bushes and the wind wrenched these webs off the bushes and sent them spinning into the air. Anyone looking upwards would see a shimmering circular object travelling rapidly. People would say that they were “at great height.” Actually they were only 30 or 40 feet above the ground, but the observers could not judge the height.

Similarly, a trans-Atlantic pilot reported with aU sincerity, that he had been dogged by a “flying saucer” flying below him. On a trans-Atlantic flight, I saw a similar “flying saucer.” It was flying below and behind us. It was not round, it was oval, rather like a flat fish with short fins. I called on my neighbour as a witness. But after about a minute it had disappeared in what was apparently a cloudless sky. With experience of desert mirages, I had no doubt about that one. It was our own aircraft being reflected, upside down, and unrecognisably distorted, as in a freak mirror in a fair ground, by an undulating layer of hot air,

above the sea. It disappeared after lay P ov er the particular

, K - S - Chandrasekar, a student at ? he University of London, writes: In the Red Sea, while I was travelling by ship to Europe, J was admiring the sunset over the Egyptian desert. The top of the red sun suddenly exploded into a plume of bright green light. Was this a solar flare?”

No, it was the Green Flash, or what the French call le Rayon Vert. A solar flare is what is visible at the time of an eclipse, when tongues of flame can be seen streaming from the corona. The Green Flash is something different. It is due to the refraction, or splitting of light, by the atmosphere. It can be seen at sunrise as well as sunset. The air has to be very clear and the horizon has to be sharp, as it would have been over the Egyptian desert.

This Green Flash has mystified people throughout the ages. The ancient peoples, who observed it at sunset and sunrise, thought that the sun turned green when, in the night, it travelled into the underworld. Some have suggested that it is just a freak of the imagination or that it is due to the dazzling of tired eyes—just as when you look at a bright red flame, close your eyes and still see the flame, but in green.

One does not need to look beyond a physical explanation. The light from the sun, when it enters the earth’s atmosphere, is slowed down and is therefore bent, or refracted, as it would be in a prism. Each colour, which means each wavelength of light, is bent at a different angle, and so can be seen separately.

When the sun is low on the horizon, it means that we are seeing it through the densest thickness of the atmosphere and it filters out many of the colours. So when the sun drops below the horizon the colours of its spectrum disappear one by one—until the short green waves remain. The “flash” is the period during which the green light persists, when the other colours have been wiped out by the atmosphere. At high altitudes, some of the other wavelengths may be detected for quite a time, so that the setting sun can appear red, orange, yellow, blue or green. The farther

nortl or south of the Equator one goes, the longer the green “flash” continues. In the Arctic and Antarctic, it has been seen for 15 minutes to half an hour. Cause of Mirages Pierre Charcot, rue Michelet, Algiers, writes: “The Arabs call a mirage ‘Bit el Shaitan,’ the Devil’s Well, and novelists always treat it as a cruel deception, but is it not actually the image of something which exists?” Yes, and no. The “lakes of water” which I have seen in the Sahara and elsewhere are not real, although the palm trees, or dunes reflected in them are. And to see a camel walking on its hump seems like a freak of imagination and yet it is the reflection of a real camel.

Mirages occur when there is a layer of very warm or very cold air above the ground. In the desert where the sun has warmed the sand, there is a cushion of hot air immediately above the ground. This is optically thinner than the higher and colder airs. That means that the light rays move more easily through it than through cold air.

Any picture which our eyes see it the reflection of light waves from some object. The simplest form of desert mirage is where the observer actually sees at a distance a group of palm trees. That image is normal but the light waves scattering from the palm trees also pass through a layer of hot air which acts as though it were a mirror and one sees a “mirror image”—upside down. But, since the hot air shimmers, it gives the impression of a reflection from a sheet of water —water that is not there.

The more disconcerting mirages, however, are those which are reflected from beyond the horizon by a hot, or cold, layer higher above the ground; then you see camels upside down walking like flies on the ceiling, or, in the Arctic, ice-bergs floating in the sky. Moon Dogs Lester Thompson, of Thornton street, Ottawa, writes: “A friend of ours, a Canadian Mountie who served in the Arctic, says that in the Far North, there are so many moons in the sky you cannot count them. We know he tells tall stories and do not know whether to believe him. What is the truth?” “Cannot count them” is an exaggeration. But, in the Arctic, one can see many moons (during winter) and many suns (during the summer). The effects can be very beautiful, but there is no great mystery. The “moon dogs” (the paraselenae) and the “sun dogs” (the parhelia) are due to the presence in the atmosphere of minute ice crystals. These crystals reflect the light of the moon or the sun. These over a large arc of the sky produce “haloes” or circles of light. These rings can lie in different planes and intersect each other. At the intersections there are bright spots which glow like mock suns and mock moons. It is not unusual to see six of these in the sky at a time.—U.N.E.S.C.O.