THE SKIES OF VENUS.

Press, Volume LVIII, Issue 17460, 22 May 1922, Page 5

THE SKIES OF VENUS.

DO THEY SHELTER LIFE ? Whether life, as we understand it, can exist elsewhere in the universe has often been a subject of controversy (writes the Astronomical correspondent of the "London "Morning Post"). In the Solar system, at any rate, it seems probable that for .the most part planetary conditions are quite unsuitable for a race of beings physiologically similar to ourselves. It has, however, been argued that, of the planets of the Solar system, it is not the much discussed Mars, but Venus that is likely to provide the nearest approach to terrestrial conditions. It is still quite uncertain how long the "day" of Venus is. It may be about equal to our own, or on the other hand it may always keep the same face to the sun, as our moon always keeps the same fape towards the earth, except for small oscillations. A third alternative has recently been suggested by Professor Pickering, who thinks he has found evidence of a period of nearly three of our days. The Three Theories. We can hardly conceive existence under perpetual sunshine or'perpetual darkness, so that we need not envy any possible inhabitants of Venus if the second hypotliosis be the.true one, however much tho probable • cloudiness of the planet's atmosphere may protect them. If the first hypothesis be.taken, day and night will succeed as they do with us, but the smaller inclinatum of the axis of Venus to the ecliptic will greatly diminish the seasonal variation. In the day sky, IF clouds. permit, the sun must be a magnificent object, with a disc twice as large in area as it appears to us. Night conditions may, however, be much more interesting. Venus has no moon of its own, and by far the most conspicuous object in its night sky must be the Earth when favourably placed. 'To an observer with sight no better than .some exceptional mortals possess, the Earth in opposition should appear as a disc, and jiot aB a mere bright point. Moreover, 'the motion of our moon round the Earth would be conspicuous, as its greatest distance would be .ahout equal to the diameter of the sun or. moon as seen from the Earth. The moon would of course be brightest when the Earth appeared "full," but it is difficult t calculate how bright a star would be to equal the light of .the moon. Inhabitants of .'the moon might very likely have advanced in their astronomical , knowledge much further than was possible on the Earth before the iiwention of the teleacipe. The Finest Moon. It has often Been remarked how lucky we are in possessing relatively the finest moon in the solar system. Jupiter certainly has four moons as large or larger than ours, but they do riot ap-. pear larger as seen from Jupiter, and. are quite small compared with the planet. The Earth's moon is nqt large, but its radius is nearly a quarter of the Earth's radius, so that it is .reasonably comparable in size. Mercury is the only planet known to us that would appear brighter from Venus, and its ecceD trie orbit woul3 be an additional advantage to the primitive astronomers of if such there have ever been. Mercury also has no moon, and though Mars has two they are exceedingly small, and give practically no lisrht. Saturn's unique ring is the only other exceptional i appendage in. the system. Naturally all the outer planets would be fainter as seen' from Venus; It must not be forgotten that it is probable that atmospheric conditions on Venus are extremely "bad for observing, as it is considered likely that its sky is permanently overcast.