IN STARRY SKIES

Evening Post, Volume CX, Issue 156, 30 December 1925, Page 9

IN STARRY SKIES

MARS, AND THE PROBLEM

OF LIFE

(By "Omega Centauri.")

Those who believe with Flammarion that life throughout the universe is universal and eternal are not greatly concerned about the physical conditions on the planet Mars. Where the natural eye sees but a few thousand points of light, that of the> mind pictures thousands of' millions of suns, and reason surrounds them with innumerable planets. No possible limit can,. therefore, be detected to the number of possible abodes of life, and life itself seems to show an infinite capacity for adaptation to its environment There are, however, still many who regard-the solar system as exceptional or even unique in the vast extent of the Galaxy. To them the possible extra-terrestrial homes for intelligent beings appear few and inhospitable. "Amongst these Mars appears the best >of a most unpromising selection. I'or this reason the ruddy planet has attracted an inordinate amount of attention.

Fortunately no subject of study fails to repay labour spent upon it,. and those who now turn their attention to the planet Mars will find plenty of problems to arouse their interest and stimulate their curiosity. Even those who do not accept his conclusions cannot fail to be delighted by the clear exposition and eloquent special pleading of Professor Percival Lowell, the acknowledged chief advocate of Mars as the abode of life. He increased a hundredfold the interest originally aroused by Schiaparelli, and this was further added to by the able opposition of Alfred Bussell Wallace. A study of the problem with these writers as our guide* shows not only how intensely interesting but also how extremely difficult it is. The latter discovery must be to most readers rather unexpected. The telescope, the spectroscope, the interferometer, the bolometer, and all tho other instruments of a modern observatory give such astonishingly accurate information with regard to the, far distant stars that we might expect to know. the solar system u thoroughly as ocr own backyard. It is a painful surprise to find that we are'. baffled by our immediate neighbours, which hide from us information we might expect them to offer freely. We have seen that even the times of rotation of Mercury and Venus and the inclinations of their axes to their planes of revolution are still stated with a query. Since the phenomena of day and night and of the seasons depend on these particular factors we are left in doubt about all the physical conditions of these planets.

In the case of Mara wo have some much more definite information. The length of the Martian day u known with such accuracy that it is usually stated to a hundredth part of a terrestrial second. R. G. Aitken, in the Monthly Sky Map; No.:218, gives it, as 24 hours 37 minutes 22.67 seconds, and the B.A.A. handbook for 1926 gives a value differing only to the 'extent of substituting a five, for the seven in the final decimal place. The axis of rotation, of the . planet is known to be inclined to the plane of the planet's orbit at an angle of 24 degrees 50 minutes. Seasons must, therefore, succeed one another in th,e same order as they do on earth, but they will be nearly twice as long, the Martian year being 22$ of our months in duration, and the intensity of the seasonal changes is still uncertain. Mars is the only celestial body, beyond the moon, of which we can say definitely that we, see its surface. Low* ell has, indeed, made maps both of Mercury and Venus, and p s has concluded that each of these planets turns for ever one face towards the su"n. But the observed markings are so difficult to detect that the conclusion, though probable, is not definitely accepted. The ' principal markings on Mars are indisputable. The polar caps and few dark shadin'gs can be Been with . small telescope?, and when observed through larger instruments, the surface features 'are so clear that detailed maps of the whole surface form a regular feature in many astronomical works. When, however, the limit of visibility is approached peculiar markings' are seen by some, and quite unperceived by others, and it is with regard to the reality or unreality of these, and with regard to their interpretation if their existence, is established, that controversy still raj^es. > All agree that Mars is the small elder .brother-of the earth. It ,1-tas already reached a stage to which th'e earth may approach in the distant future. A study of its present state may give us some premonition of the fate in store for our own planet. Being so much smaller, Mars has run through its changes far more rapidly than the earth. Mars has a diameter of 4200 miles, nearly twice thili .of the moon,,but little more than that of the earth. Its volume is a sixth and a seventh, its sur-, face over a quarter, but its mass little more than a tenth of terrestrial values. Its' density is under four times that of water, whilst that of the earth is over five and a half. The force of gravity st its surface is less than two-fifths of what i we are accustomed to, so that engineer- , ing fiats on Mars* would be far less difficult than they are here. Mart will be in opposition again on 4th November, i 1926, but it will not be as near to the [ earth as it was lastgrcar, nor will it be quite so favourably placed, as its deelination will then be nearly fourteen and a half degrees north. The Martian year being 687 of our days, and the ter- ' restrial one only 365.26, the earth gains a full lap on Mars every 780 days. Oppositions therefore occur regularly at intervals of this length,-lint they are not by j any means equally favourable for obser-, vation. , .

The orbit of Mars is more eccentrie than that of any other planet except Mercury. . Its distance from the sun varies from 130 to 155 million-milef. The earth, although moving in ft much less eccentric orbit, is sometimes five million miles farther.from the son than at other times) The distance between the orbits thus varies from 35 to 65 million miles, and at certain .oppositions Mars may present to ns a disc nearly twice the diameter that it shows at others, but for a few months every two years or so Mars shines in the sky with a fiery orange light, often far surpassing Antares, its rival in the heart of the Scorpion. Galileo discovered its phases in 1610, and Fontana in 1636 caught the first "glimpse of the^ dark markings on it* surface. Huygens' made a drawine of it in 1659, and seven years later Cafisini made a determination of its period of rotation.- Maraldi noticed the polar caps, in 1710, and Sir William Herachel proved, tesHtfd* tfat end of thi utta?, tiu*

their Tgriations in tin oorrMpcnd with the Martian seaioni. Beer an& Madler mada b chart of the planet during the opposition of 1830, which was the moat favourable one in the nineteenth cenrnry. But the discovery which created tte greatest interest was made by SchUparelli in 1877. He noticed a nninb«ir of streaks crossing the bright region's which were then called continent*, and gave" to : them the Italian name' eanali or channels. This name was loosely translated into the English word "canals," and has given riae t? much misunderstanding. Sehiaparelli's announcement was received with scepticism, for although he reH>beerT-' ed them in 1879 and 1881 it was net until 1888 that other observers »«V ceeded in seeing them at all, andevciL. yet some of the most eminent,obse'rv-" : ers fail to see them. Professor Bari nard was one of these. But M.Perrotin in France, Mr. S. Williams in" England, and the astronomers using the 36-inch telescope at Lick confirmed Schiaparelli's observations. In' 1892 Professor Pickering found that the eanali crossed one of the areas called seas and two years later Dr. Lowell and Mr. Pouglass found, them crossing all the seas, and'pointed ont seasonal changes which they; maintained were due" to vegetation. - . Since then popular interest has been focussed on the planet. Lowell was not content merely to draw and describe the markings; he offered a graphic and detailed explanation of their origin and meaning, and 'he clothed his ideas in such beautiful language that, his books are a pleasure to read^ Those who have not airealy done so should peruse '-i.Mars and Its Canals," "Mars.as. the Abode of Life," and "Tho Kvolution \ut Worlds." Those who tiavc already studied these will find a delight in renewing their acquaintance with them. For the other .side of the ques-. tion they should consult "Man'j Place in. the Universe" and "Is Mars Habitable!" by A. B. Wallace. Finally, the results of the observations made during the last .opposition may. be found in the, current astronomical; journals. '•' '■'":.".:.■■"'-' ■■ ... ■' "• "-:;• .'■;

In 1877 Professor Asaph KalJ, with the 26-inch telescope at Washington, made an; astonishing discovery; one, however, which has^itlle, bearing on our present problem of suitability-for life. . He found that two tiny mooes were racing round, the plSnet."' Tho: liearer one, Phobos, revolves at a distance of only, 3700 , miles froni the surface of the plapet and makes tKft journey in. seven hours .thirty.tJiitio minutes, which is,less than,onc-third of the Martian day. It is.a most'r?markable ' coincidence.' that jta' 'Outliver/s travels the astronomere of Laputa are said to. have; diseove red two. satellites of -Mars,: one, with, this> un-, precedented property of r rapid 'revolution. - Deimos also behaves in .< a strange : way. . It* ■ pe:tioa: is thirty hours eighteen minuj^s, so it remains above the Martian horizon for nearly three ' days; without ■ setting, going through all its phases'twice over during that time; . V ■ '