MARS.

Taranaki Daily News, 17 September 1921, Page 6

MARS.

THE PDOPOSED GIANT TELESCOPE.

IS IT FEASIBLE?

(By the Honorary Director, New mouth Observatory.)

The planet Mans revolves in its orbit round the sun once in every 087 days. The shorter period taken by the earth on its smaller orbit, together with its more rapid motion, causes an opposition (that is to say, the position taken up when sun, earth and Mars are in line) to take place every two yearS. The orbit of Mars, however, is considerably more eccentric that that of the earth. Consequently each opposition differs in respect to the distance which then extends between the two planets. The last favorable opposition took place in 190!), when Mars was about 36,000,000 miles distant from us. A still more favorable opposition will occur in 1924, when the distance will be further shortened by about a million miles, and the planet, which at the least advantageous opposition only subtends' an angle of 13 seconds of arc, will then expand to a diameter of nearly 30 seconds, so that, with a magnifying power of only 60 diameters, a telescope will show Mars apparently the same size as the full moon appears to the unaided eye. There will be a very good opposition of Mars next year, but considerably inferior to that of 1924.

DOES LIFE EXIST? Does intelligent life exist upon the red planet Mars? This question, we would be glad to believe, is to receive a definite answer in the not distant future. In a recent cablegram appears a report that a wealthy Amercan is financing a scheme which, if successful, will revolutionise the science of astronomy, in so far as our knowledge of the physical features of the heavenly bodies is concerned. A giant telescope, having a rotating mercury mirror 50ft in diameter, is to be erected at Chanaral, on, the Chilian coast, and, it is further stated, will bear a magnifying power of 25,000,000. Even to the uninitiated, these figures will appear very large; to anyone that has had experience of telescopes, they will appear impossibly so; he will wonder if the calculation (save the mark!) is not carried out upon the principle of setting down 25, and adding as many noughts as the line will hold.

GRAVE DIFFICULTIES. There are grave difficulties which are apparently able to frustrate the utility of such an instrument as is proposed. Setting aside the initial one of getting a 50-foot dish of mercury to rotate so as to make its surface take on a true parabolic curve, and to retain that curve unalterably for any length of time, there is the more serious difficulty of securing the perfect steadiness in the mechanism which is essential to success. Supposing only a tremor so slight as to occasion a movement at the focal point of the mirror amounting to no more than the thousandth part of an inch, a magnification of one thousand diameters (to say nothing of 25,000,000) would make Mars to appear instinct with life, no doubt, but hardly of an intelligent kind.

TERRESTRIAL DISTURBANCES. But the oustanding difficulty, after all, lies in the disturbance which is constantly taking place in our terrestrial atmosphere. Few and far between, even in the most favored regions, are the moments when high magnification can be as every astronomer knows, and' that to speak only of thousands, certainly not of millions, of diameters.

Altogether, the proposed scheme for bringing Mars to an apparent distance of one and a-half miles looks too good to be either true or feasible, and it will be wise on our part not to permit expectation to soar to an undue height, in spite of the assuring tone of the cabled statement.