Evening Star Newspaper, March 17, 1935, Page 81

THIS WEEK A strip of the New Moon as seen through a 100-inch telescope Photograph from Mt. Wilsors Observatory Explorers of the MOOII ' While ““Rocketeers” still plan their voyages to the Moon, scientists have brought the Satrellite into their laboratories, have studied its “weather’, its volcanoes and the material of which it is made by GEORGE W. GRAY Bishop John Wilkins. founder of the Royal Society, published his curious treatise, ‘'The Discovery ofa World in the Moon, and the Possibility of a Passage Thither.” In 1935 we are still discovering the world in the Moon, and the possibility of a passage thither continues to tempt some of the adventurous- - particularly the rotket-builders. These rocket-builders, who expect some day to achieve an interplanetary passenger ship, generally list the Moon as their first stopping place. The satellite is so near - only 221,000 miles, at its nearest, as com- pared to millions of miles to Mars or Venus—it seems the obvious first port of call. Indeed, it is reported that a prominent citizen of Cleveland, Ohio, wealthy member of the Cleveland Rocket Society, has created a trust fund of $20,000 to provide for the burial of himself and wife on the Moon, should they die before the first passenger service starts. Meanwhile, and quite apart from these rocketeering ambitions, a group of distin- guished scientists have been quietly working on the more immediate task of exploring the Moon indirectly, through lenses, mirrors, prisms, thermocouples and other apparatus. The 100-inch telescope at Mt. Wilson Observatory gives them a view of the moon so large that it is as though the observer were looking at it from a distance of only 200 miles, and details 500 feet wide are distinguishable. Recent advances in photography have been enlisted, and on Mt. Wilson a Moon House has been built as a special laboratory. Here images of the Moon a:e photographed on globes, thus bringing the Moon into the laboratory, as it were, and permitting the explorers to see their world in the round. Prior to the organization of this group, all that was known of the Moon had been gathered by specialists in astronomy. But the problems involved are more than astro- nomical, and Dr. John C. Merriam, president of the Camegie Institution of Washington, felt that the collaboration of many sciences would be needed to get at the true facts about the Moon's surface — its rugged terrain, wide-spreading plains, precipitous mountains, its vast craters and the curious streaks radiating from some of the craters. So when, at Dr. Merriam's recommendation, the Com- mittee on Study of Surface Features of the Moon was appointed, it was composed of representatives of different branches of science -with a geologist, Dr. Fred E. Wright, as chairman. The fundamental question is the nature of the material in the moon. Apparently it is all IT 1S nearly three hundred years since solid, for there is no evidence of any liquid and much evidence against the existence of any atmosphere. So the moon geologists con- clude that we are dealing with a solid globe on which no rivers ever flow, at whose poles no ice ever forms, and round whose mountains and across whose plains no breezes ever blow. Ordinarily we identify material by examin- ing and analyzing a specimen. But we have no specimen of the Moon except its light, and that light is not its own, but reflected sun- light. With it we can see the shape and color and superficial markings of the Moon, but can they bring any intimate news of the material itself, of its physical nature and chemical makeup? Not directly, perhaps, but by The Earth as seen from the Moon—an artist’s conception A painting by Howard Russell Butler, Courtesy American Museum of Natural History ingenuities the explorers at the telescope are turning up clues. When they compare sunlight with moon- light, for example, they find slight differences. Certain characteristic vibrations found in sunlight are nipped off and smoothed out in the process of reflection, so that a small percentage of moonlight vibrates in only one plane, and because of this it is said to be ‘‘polarized.” In fact, any light that is reflected — whether from a glass mirror, a white snowfield, a blue sea or any other reflecting surface—is partially polarized. But the degree of polarization varies with the material; indeed, is quite individual to the material. By measuring the polarization of moonlight at all phases, the lunar detectives obtained a sort of optical thumbprint of the material of the moon. Then they searched various Earth materials to see whether'any of these showed the same thumbprint. It was proved that the Moon stuff cannot be opaque like the charac- teristic rocks of the Earth. Only a translucent material can polarize light into the peculiar pattern of moonbeams. Thus the tests nar- rowed to a few materials. The Full Moon, showing the streaks from the craters Photegreph from Yerkes Observetory Still another clue is furnished by the tem- peratures on the Moon. It has long been suspected that this satellite of the Earth is a world of violent extremes, of alternate chills and fevers — but not until the thermocouple was perfected and adapted to these faraway measurements was the fact known. Each one of the two receiving parts of the thermocouple is a structure of metal hardly larger than the period at the end of this sentence. But with this tiny thermometer the lunar explorers have been enabled to range over the lunar surface and measure the heat of different areas at noon, sunset and midnight on the Moon. The range is eriormous — from a noon tem- perature of 250 degrees Fahrenheit (hotter than boiling water), to a midnight tempera- ‘ture of 150 degrees below zero. Not only that, but in time of lunar eclipse, when the Earth passes before the Sun and shuts off the source of this heat, the temperature on the Moon falls within a single hour from the temper- ature of boiling water to 150 below zero. The speed of this “‘cooling off’’ was care- fully calculated. Then various materials of the Earth were tried, to learn if any showed the same speed. Pumice stone, it was dis- covered, had a cooling rate corresponding closely to that of the Moon. Pumice meets the temperature test — it heats up quickly and just as quickly gives up its heat. It also meets the polarization test - for it is a translucent material and polarizes light in 2 manner corresponding to that of moonlight. In still a third particular, pumice seems to qualify as logical Moon material — and that is in its volcanic origin. For on the Earth pumice is the hardened material that is shot out of volcanoes — and since there are thousands of craters on the Moon we cannot but speculate on a possible past when these craters were active. The Committee on the Moon offers no theory to account for the origin of lunar vol- canoes—though Dr. Wright points out that a massive colliding meteor might easily gener- ate such heat as to cause a volcanic eruption. Another bit of evidence which suggests volcanoes is the presence of the long streaks radiating from several of the craters. By the standards which exist on the Earth, it would be impossible for a volcano to erupt material to such distances. But there is no air resist- ance on the Moon and the force of gravity there is less than it is on the Earth. The German gun which bombarded Paris during the World War had a range of seventy-five miles, but on the Moon, Dr. Wright points out, the same gun would have a range of 2,200 miles. Rays from the great crater Tycho have beer traced for 1,500 miles, and there is no reason to doubt that a volcanic outburst on the Moon could scatter pumice for 1,500 miles and even greater distances. ‘We must picture the Moon then as a desert world, vast plains of pumice-like material pockmarked with craters and ringed with jagged mountains, boiling hot by day and frigidly cold by night, airless and waterless and lifeless — hardly a friendly port for an interplanetary stop-over.