A Trip to the Planets.

Star (Christchurch), Issue 18959, 4 January 1930, Page 13

A Trip to the Planets.

Amazing Differences Would

Greet Visitors .

IF HUMAN beings could make' a trip to, the moon and to Mars, what would they find? Writers of popular fiction have long wondered what sort of people, if any, inhabited the other plan ets and what sort of landscapes would greet the eyes of the first person bold and inventive enough to invade the heavenly bodies nearest the earth. Science knows that the moon’s surface is broken by thousands of rings or craters of various depths, numerous mountains, and vast plains improperly called seas. This knowledge gives us some basis for conjecturing how the moon would look if an earth-dweller surveyed his surroundings on the earth’s satellite. There is no need for modern astronomy to guess what type of surface the moon possesses. Modern astronomy knows for a certainty how high its mountains extend, how far its plains stretch and what their relative shapes are. Geometry and the science of per spective have made possible the con struction of accura'e miniature models. It is now known that many earlier treatises which represented the moon as a sphere with sugar-loaf mountains and vat-like molehills are inaccurate Actually the mountains on the moon have profiles comparable in steepness to the mountains that exist upon the earth. The great majority of the circular formations are of such a size that a visitor from the earth would be unable to see their whole extent in a single glance. It would be necessary to turn round in order to see their circular walls, which would appear like a lone chain of more or less irregular mountains. Because the curvature of the moon is greater than that of the earth it would be impossible to see as much of a mountain that extended, say, five miles on the moon, as it would be if the same conditions existed on the moon as exist on the earth. Conditions, however, are not the same. While the contour and the gen eral outline of the moonscapes would undoubtedly amaze the visitor from the earth, the difference in atmospheric conditions is more likely to impress themselves upen him with some degree of surprise. Astronomical science is not positive whether the moon is absolutely without an atmosphere or not. Despite the ac tivities of hundreds of telescopes oi* the surface of the earth, star-gazers have never been able to detect the presence of one. If this is so there is no air to scatter the light coming from the sun and this orb of day is enthron ed in a black sky, dotted with stars as if at night. Atmosphere being absent a harsh light marks every detail, near or distant, with the same dry and in sistent sharpness. This situation is, of course, quite dif ferent from the situation which exists on the earth. Here different cjistancesmerge harmoniously in blending vap ours. Yet the life of an astronomer, were this the only circumstance to be taken into consideration, would be more productive on the moon, since he no longer has to bother about the atmo sphere which presents serious obstacles to him by cutting off the light that comes from the stars. If his eyes were not dazzled by the blinding rays which come without hindrance from the sun, the visitor from the earth .would find himself encom passed by many more stars than shine forth m the heavens that surround the earth. The rise and fall of the sun, too, would be different. At sunrise there would first appear the radiant glory of the sun’s corona, and, afterwards, those gigantic rose-coloured flames which are never visible on the earth except dur- j ing a solar eclipse.

Because the rotation time of the moon is twenty-seven times less rapid than that of the earth, the visitor from the latter planet could watch the rise of the sun quite at his leisure. The apparent movement of the stars and the heavens is twenty-seven times as slow as it appears on the earth. Though the cky itself would appear almost motionless there is one celestial body which would appear to be at rest. That planet is our own earth. To the visitor from the earth, his native planet would appear thirteen times as large as the moon appeared to him when he lived in Europe, the United States, or other* of the earth’s territorial divisions. Of all the planets astronomers can tell most about the moon. The facts possessed by astronomers about other heavenly spheres are fewer and consequently admit of less detailed interpre tation. The “fixed stars” are so distant that their relative positions appear the same from whatever planet l they are observed. The various plan ets, however, assume varying degrees of brilliance, depending on the planet from which they are sighted. The sun, too, appears to differ in size, according to its distance from the planet upon which a visitor from the earth chooses to station himself. On Mercury, nearest to the sun, that great orb is of course largest. On Venus the sun appears a trifle smaller than it seemed on Mercury and on Mars a trifle smaller than it seemed on the earth, Regarding Mercury and V’enus, astronomers know little, but Mars has been studied closely enough to admit of fairly accurate description should a visitor ever succeed in reaching the bounds of that popular planet. If the visitor should station himself on Mercury, he would immediately be confronted with a problem Mercury continuously turns her same side to the sun. One part of the planet, in other words, is always in “day” and the other in “ night.” If the visitor from the earth desired to find rest under the same conditions that prevail on the earth, he would either have to journey to Mercury's other hemisphere or, ad mitting the impracticability of living in on Mercury, resort to Mars. On Mars day and night are scarcely longer than they are on the earth Mars, however, besides having the lull splendour of the stars as they exist on earth has the advantage of having two moons. The atmosphere is very similar to that which prevails on the earth the visitor from that planet would find and the earth would appear to him situated as he is, as a morning or even ing star, depending on the various cycles that obtain in the relations be tween the planets. Because of the rar ity of the Martian atmosphere, the visitor from the earth would find the periods of twilight extremely short Its ground would be practically flat, probably level almost everywhere and cut nere and there with immense swamps. An even greater surprise, however would greet the visitor from the earth if he pursued his journey further, moving oward the giant pianets that lav further from tin. sun. Upon Jupitei Saturn, Uranus, and Neptune, he would no longer find himself on solid ground since it is very probable that these worlds are yet fluid or in such a condi tion that they do not admit of a solid surface. (Anglo-American N.S. Copyright )