EARTH AND MOON

Evening Star, Issue 20048, 13 December 1928, Page 12

EARTH AND MOON

COLLISION IN FAR FUTURE LUNAR INFLUENCE STRONG Sir Oliver Lodge, speaking at Morley College ; 'Westminster, has visualised the possibility of _ the moon colliding with the earth millions of years from now. That it should do so is a perfectly reasonable expectation. If a ball held by an clastic band is set revolving about tho hand it will soon uso up its energy, and the elastic, previously stretched by tho centrifugal force on tho ball, will pull tho ball back to tho hand. In the case of the earth and tho moon tho clastic band is replaced by the gravitational attraction between the tiro, which should surely bring the moon to tho earth when its energy is dissipated. Buch a theory may appear somewhat at variance with tho generally accepted belief that tho moon was once part of the earth and was thrown off jrom it many thousands of years ago. IVo must remember, however, that conditions then were very dilfcrent to those at present. Tho earth has not only gradually cooled off, but it has been losing iu its rate of rotation. There is evidence to show that at one time it must havo rotated onco on its axis in about five hours. This alone would increase its centrifugal force over that ol to-day by nearly twenty-livo times. ENERGY GRADUALLY USED IT. This force, together with tho attraction of tho sun and perhaps other concurrent violent internal changes, apparently resulted iu a large portion of tiro earth being thrown out into space to form our uresent moon. When the energy from this giant disturbance has been used up, as it is steadily going on through both water and earth tides, tho moon will gradually return. Granted that tho moon was thus born of tho earth, it is but reasonable to expect that it would partake of many earth characteristics. This is actually quite far from tho case. Study lias shown that they are quite unrelated. VAST DIFFERENCES IN MASS. One obvious reason for this great difference is found in their respective mass. The moon being but I-80th the mass of tho earth, its gravitational attraction on objects on its surtacc is reduced by this factor. The most anaemic individual among us, given a few hours on tho moon, could establish athletic records that wo could never hope to equal. He should do a high jump of six times his record here. He could act like a gigantic grass hopper. Ho could carry a mass equivalent to about a ton here. That provided, of course, that conditions other than gravity were the same as-hcre. As it happens, however, lie would find some difficulty < in breathing, for, with so little gravitational attraction the moon is capable of bolding only a very rare atmosphere, if, indeed, it can bo said to have any at all in comparison to ours. Not only would this affect his wind, hut its absence would result iu very intense cold, for tho atmosphere we have acts as a blanket to shield us from the blaze of flic sun during the day, and to hold in tho heat at night. FOURTEEN DAYS OF SUNLIGHT. An individual on the moon would be subject to fourteen days’ continuous exposure to tho sun, and would then have a night period of fourteen as the moon rotates but once in twentyeight days. During the day period the temperature would approach that of boiling water, and for the other fourteen days the cold would be more intense.than wo can easily imagine. Whether or not water exists on the moon has always been a question. The dark areas which go to make up what is commonly called tho “ man in the moon ” were previously thought of as seas; they are now considered to be vast desert plains. The German scientist Fauth believes that the whole moon surface is encased in a thick ice shell. Others claim to have observed what appeared like water vapour, forming clouds, over certain regions, and some have claimed to have observed traces of snow in crevices not directly hit by the sun. If there is water it is probably frozen.

CRATERS A MYSTERY. One moon problem that has ns yet delied attempts at solution is .tho existence on its surface of the peculiar circular craters. These vary iu size from those too minute for us to see to those of a diameter of a hundred miles or more. They are as much as ten miles deep, and have usually a pinnacle in their centre. There are thousands of them. It has been suggested that they were caused by meteors falling into tho moon, and it can be shown that throwing a hard object into soft mud will just such a formation. Indeed, in Arizona there is such a crater which has been formed by a meteorite. But that is just one, and so email as to ho impossible of observation if it_ were _on the moon, and tho earth is subject to bombardment by meteors as much as the moon is. The fact probably is that those craters are volcanic in origin, although probably not caused by a volcanic eruption such as wo know on the earth. The nature of tho action is difficult to discover. MOON INFLUENCES LIFE HERB. Iu these days of modern lighting we have come to disregard the moon, whoso light played a very important rolo in the lives of our forefathers. Nevertheless, our lives are very decidedly influenced by the moon. Perhaps this is most obvious iu tho case of ocean tides, which we must take account of in coast shipping and in tho construction of waterfronts. That these tides will play a more important part in the future is evident from the attempts that are now being made to harness them for power projects. Tho time is not far off when these plans will ho economically feasible. In addition to the wafer tides there are also easily measurable earth tides; resulting in bulging and contracting on the earth's crust itself. As a result of tin's the earth rotates sometimes faster, sometimes slower, and a difference may even exist in the length of two successive days. Differences in the observed positions of stars, previously thought to bo experimental errors, have been shown actually to be due to this changed rate of rotation. Sometimes the earth was ahead of its calculated position, thus making the stars appear behind, and sometimes flic reverse was true. LINKED TO EARTHQUAKES. Professor Beniamin Boss, of tho Carnegie Institute, of Washington,_ has correlated these star variations in a largo number of cases with , sex' sin ic disturbances. If changes in the earth’s crust cause earthquakes, as might bo presumed, variations in apparent star positions should coincide witli them. In his study ,he has dealt with 18,270 seismic disturbances, end has found excellent confirmation of tho theory. Old gardeners used to say that seed should ho planted in the full moon if it is to germinate quickly. Recently it has been shown that because a largo percentage of the light we receive, from the moon is polarised this effect on plants is real. It affects germination and Jlowcring. Numerous other effects on plant and animal life as well have been found. Although we may forget about the moon, and almost disregard its presence, it is, nevertheless, exerting a very definite influence on the whole trend of our lives, and of mankind in general, and probably will, as Sir Oliver Lodge says, eventually return to tbo earth and stop the progress of life on this planet altogether.