Serious students of Mars, says French Astronomer Gerard de Vaucouleurs (in a new book, The Planet Mars; Macmillan, $2), wish that laymenand some astronomersdidn't spend so much time debating the "canals" of Mars. Do the canals exist, and if so, were they built by intelligent Martians? "This great quarrel about the canals," says De Vaucouleurs, "has brought much discredit upon the study of the planet." It would be better, he thinks, to forget the canals and the Martians for a while and concentrate on studying Mars objectively with science's brand-new instruments and methods.
Dust & Vegetation. In layman's language, De Vaucouleurs tells about the new, highly sensitive spectrographs, thermocouples, etc., which have recently yielded an astonishing amount of information about Mars's atmosphere, climate and topography. Most experts agree, he says, that the planet's great light-orange areas are covered with fine dust, probably containing silicon compounds like the soils of the earth.
In the thin atmosphere, which contains a little carbon dioxide (necessary to life as earthlings know it), float three kinds of cloud. Near the surface are yellow clouds (probably airborne dust). Higher up, at about six miles, is a thin violet layer, perhaps of much finer dust. Higher still, at six to 19 miles, float blue clouds which astronomers believe may be made of minute ice crystals, like cirrus clouds on earth.
The brilliant white patches that form in winter on the polar regions of Mars are believed to be ice crystals, probably hoar frost. The layer is very thin and may not even cover the surface completely. When the ice melts as the sunlight gets stronger, a dark fringe is left around its receding edge. This is believed to be moist soil. Simultaneously, the dark patches between the icecap and the Martian equator grow darker progressively, the color change advancing in a sort of wave at about 28 miles a day. The darkening is believed to be a seasonal change of some sort (perhaps the growth of vegetation) caused by moisture from the melting icecap carried to lower latitudes by the wind.
Illusions & Mysteries. With careful objectivity, De Vaucouleurs gives these facts about Mars and many more, but in spite of his good resolutions; he cannot resist discussing the canals either. Some skilled observers, he says, see the straight, criss-crossing canals in great profusion, looking just as if they were leading irrigation water from the icecaps toward the Martian equator. Others see no canals, and claim that they are mere optical illusions caused by too much peering at a hazy, jiggling object that, even in 'the finest telescopes, looks no bigger than the moon. Photographs do not settle the question. During the long exposures needed, Mars moves about too much to show such fine details.* An in-between school holds that "canals" exist, but that they are actually small dots or patches arranged in straight lines.
Summing up the arguments of both factions, De Vaucouleurs concludes that "there is something remarkable on Mars . . . which calls for the most energetic research . . . Mars remains the only planet whose phenomena cannot easily be interpreted by the sole use of the physical and chemical laws applied to inorganic matter."