THE SKETCHES.

Otago Witness, Issue 3519, 23 August 1921, Page 52

THE SKETCHES.

THE DAILY INFLUENCE OF [ ASTRONOMY. jt PROBLEMS SOLVED A >, 1J :e L X SOL VED. U A deeply interesting article on “The Daily Influence of Astronomy was con- 1 tributed by Dr W. W. Campbell to a 6 recent issue of Science. i’rom this we * make the following extract: f Shall wo try to estimate what astronomy, the oldest of the sciences, some- < times called an ideal and unpractical 1 science, has done for mankind ? tlere. are 1 some of the applications of astronomy to 1 daily life. ’ ' 1. Observations of the stars with the s transit instrument, such as exists in this : observatory, are supplying the nations * with accurate time. Two astronomers, 1 with modern instrumental equipment, ' situated on the same north and south line, * may observe the stars so accurately, in comparison with the beats of their com- ‘ mon clock, that they will agree within ‘ two or three hundredths of a second as , to how much that clock is fast or slow. 2. The accurate maps of the continents . and islands depend upon the astronomical , determinations of the latitudes and longi- 1 tudes of their salient features. 3. The sailing of ships over long courses 1 —say from the Golden Gate to Sydney. 1 Australia, or from New York to the Cape £ of Good Hope—depends upon the A B C"s < of astronomy. Given fair skies, the navigator may locate his ship in the middle 1 of the broad ocean within a mile of its * true position. ( 4. In America it is the habit to call upon the astronomers to fix the boundary lines between nations, by observations of 1 the stars ; for example, along the 49th 1 parallel of latitude, from Rainy Lake, Minnesota, westward almost to the Pacific Ocean. The uncertainty as to where this ( imaginary line falls upon the ground is * nowhere greater than 10ft or 15ft, and . it has not been found necessary by us, 5 nor by our friends in Canada, to maintain military forts along that line. , 5. The times of high and low tides, vital ] to mariners in entering many harbours, < are determined by or from the work of the astronomers. j Ve do not dwell upon these responses < to the immediate needs of the world, for i they are unimportant in comparison with 1 the contributions of the pure knowledge ; side of astronomy to progressive c.ivilisa- < tion. ‘ “ , Let us think of the earth as eternally i shrouded in thick clouds, so that terres- 1 trial dwellers could never see the sun, 1 the moon, the comets, rhe stars, and the 1 nebulae, but not so thick that the sun’s i energy would fail to penetrate to the soil < and grow the crops. Under these co-ndi- i tions we might know the earth’s strata 1 to the depths of a mile or two. We 1 might know the mountains and the atmo- 1 sphere to a height of four or five miles. We might acquire a knowledge of the < oceans, but we should be creatures of i exceedingly narrow limits. Our vision, i our life, would be confined to a stratum < of earth and air only four or five miles t thick. . H would be as if the human race went 1 a.rout its work of raising corn for food i and cotton for raiment, always looking ; clown, never looking up, knowing nothing i of the universe except au insignificantly ’ small stratum of the little earth. This picture is only a moderately unfair view . of life as it existed on oiir planet 400 . years ago, before the days of tire tele- ' scope, the spectroscope and the photographic plate, before the days of freedom . o.‘ speech and thought, which came with \ the scientific spirit. The earth is for us no longer flat, supported on the back o. a great turtle, which rests upon nothing, it, •* round, and every civilised . person knows that U, k. Exists there an ! intelligent man in the world whose thoughts, every day and many times a ' City, are, not unconsciously adapted to this < iUctl tois. knowledge is a chief inheritance of the now generations. It, is fundamental in our civilisation. People know ' ti'J. i/M u.r. will rise in tiro morning and set in the evening, and why? A round i eaith rotating upon its axis in a dependaule wav and revolving round the sup in exact obedience to law, are truths incom- j ' p irahlv snora sublime than the fiction of j ! Hat _ earth which was pictured hazily i ’’’ r,!e "’ 3 . minds during pre-Copernicari 1 , Wf! ° , sn estimate the value of this 1 kr.o'.v-.cdga t..» the human race? It can ! m_’* be expressed with the few figures ' which suffice for the total of present-dav ' financial transactions. ' ‘ j ’ —Other Worlds Than Ours , T'hij stars are not lanterns hung out in j tnc sky by angels at night, but some- ; thing inconceivably greater; they are 1 suns, hundreds of millions of suns, on the 1 average comparable in size and brightness 1 to oilr sun. Is not this ascertained fact ' OI Nature a most ennobling one to aspir- 1 ing souls? Do not these facts suggest and develop becoming modesty in the minds of those who would know (lie truth and pattern lln-ir lives in accordance with it? The following conversation otanned one 1 Saturday evening in the month of dune . 1912, at the eyepiece of the great tele- : 1 scope which Mr Warner and Mr Svaeov ' i constnief 1 and erected f-the Lick Observatory; I mention the time. June, 1912. < because it is of the e.-smec of the story." i Said the astronomer to the party of visitors : ‘The object which vou will see through j the great tides. 1 q>e this evening is tile \ star cluster in Tier id ilie finest cluster j in the northern sky. Without the tele- I scope., by naked eye. this cluster may be \ seen if the observer knows exactly where l to look and has first-class eves, but he ' will see it as apparently a single star on the limit of vision, so faint that many I eves will not see it at all. Tire telescope I separates the cluster into a multitude of i . stars. If vou had the time to < emt them ; they would number fully 6000, closely i 1

grouped in the centre of the cluster, but thinning out as you approach the edges. This one object, then, which to the naked eye seems to be a single star on the limit of vision, consists of at least as many stars as the eye alone La able to see in the sky as a whole, northern and southern skies, summer and winter skies combined, and we do not doubt that long photographic exposures on the cluster, with a large reflecting telescope, would record many more than 6000. Each of these stars is a, sun, and probably every one ot those which you xvill see is larger than our sun. for we are observing merely the brightest members of the system. Ae do not know- whether those suns have planets revolving around them or not, as the cluster is entirely t-oo far away for us to see such planets, but planets probably exist there in great numbers; possible there are planets revolving around all of those stars ; possibly and probably there are moons revolving around the planets ; and, finally, there may be life, vegetable, animal, intelligent life upon those planets.” One of the visitors upon, descending from the observing chair, much interested, ouestioned the astronomer: “Did you say those stars are all suns?” “Yes, sir. “Did you say that those stars are really larger than our sun on the average?” “Yes, sir.” “Can \mi give me an idea how large our sun is?” “Well, if it were a hollow shell, of its present size, you could pour more than a million earths into it, and there would still be much occupied space between the earth balls.” “You say, there are possibly or probably planets revolving around many of the cluster stars?” “Yes, sir.” “And many of those planets may be inhabited?” “Yes, sir.” “Well, then. I think it does not matter very much whether Roosevelt or Taft is nominated next week at the Chicago Convention.” Of course, the visitor’s interest in the outcome at Chicago was just as keen as ever, but he had evidently received a valuable lesson concerning man's place in Nature. —The Wonders of our Sun—are many and most remarkable, and arc but little known. I have referred to its enormous size. The cuiantity of heat which the sun is radiating into surrounding space, to the earth, to Mars, and to all other objects which intercept its rays is stupendous, and not to be comprehended by the astronomer or the mail ol affairs. It is, and has been, the source of all the energy upon which we draw, save only a negligible residual. A great quantity of heat is indeed stored up in the interior of the earth, but it reaches the earth’s surface in such minute quantities that in all practical details of life, save to thoeie who labour in deep mines, or live near volcanoes, or are interested in hot springs, this source of energy max be neglected. If this statement should be difficult to accept, let your thoughts travel to the South Pole of our planet. What does the interior heat of the earth do for that region? The antarctic continent’s perpetual covering of ice and snow is unaffected by_ it, nor does the actually enormous quantity of solar heat falling upon that continent suffice to remove the white mantle. If aught should intervene to cut off the sun’s energy from the earth for one short month, the tropics would attain to a state of frigidity to which the south polar continent, as now observed, would be a rose garden in comparison. It is the sun's heat which grows the farmer’s crops, the trees of the forest, and all vegetation. The coal deposits upon which we draw to-day for the run ning of trains, ships, factories, and roiling mills are but the solar energy of an earlier age, compressed, transformed, and preserved for our comfort and power. In the mountainous regions of our land, where water can be stored in high-level reservoirs, and, passing through watei wheels at lover levels, be made to generate electric power for lighting, for heating, and for the running of motors, it is tho sun’s energy which is transformed tc meet the needs of men. The sun’s rays evaporate the surface waters of the oceans, lakes, streams, and lands; the winds, generated by the unequal solar heating of our atmosphere, transport some of the water vapour to the high mountains, where it is deposited as rain oi snow. It is merely the descent of these waters to the lower levels that is controlled by man and transformed into electric power for his own purposes. It would take more than two billion earths placed side by side to form a continuous spherical shell round our sun at distance equal to the earth’s distance, and thus to receive the total output of solar heat. Therefore less than one two billionth part of that output falls upon the earth. r l he earth’s share of solar energy, expressed in horse power oi other familiar units, is too great to set down in figures. If you should happen tc own 250 acres of land in one of the tropical deserts of the earth, you will be interested to know that your quota of the solar energy, near the middle of a summer day, is falling upon your tract ol land at the rate of about 1,000,000 horsepower—more than enough heat and power to supply all the needs of this great city.—and this is but two-thirds of tin sun’s good intentions toward you, for some 40 per cent, of the energy is intercepted by ihe atmosphere overlying yom farm, and returned forthwith to outer space. Your neighbour's tract of 250 acres b al ■<> re; riving solar energy at the rate ol IjOOO.OOO horje power. Figuring backward, if one farm area received 1.000,00 C horse-power, and there are more than 100,QU0.000 such farm areas on the cart!" turned towards the sun at one time, and the whole earth intercepts less than one two-billionth of the sun’s energy- output, is it any wonder that sun worship became one of the recognised religions? Accurate knowledge save:-, us from that, but it is becoming in us to give tho bud otu due respLVt.

t A Great Problem Ahead • oi the scientific world is the storage of the j. 1 sun's beneficent heat rays for release as j “ needed. Astronomers are seeking intently j lor the sources of the sun’s outpouring j 1 energy. How can the sun maintain the I 1 supply for tens of millions of years, as it j ’ undoubtedly is doing One important ; source has been found—the sun's own j I gravitation, which tries constantly to pull i every particle of its material to the sun’s j | centre. But another and greater source i scorns to await discovery. Does anyone ! say, since the supply of solar energy will i ® surely meet our needs for ten or a hun- 1 e died million years, whv look further j ® for the cause ? Why not let it go at 1 that? This selfish spirit, if applied to all ' subjects, would retrograde our civilisation. Even the possession of the truth q is not so potent for good as the desire > to know the truth and the struggle to dis- ' cover it. Practically a knowledge of tho I origin of the sun’s beat may be the key ■ ’ for locking up great quantities of it on II summer days and unlocking it when and where needed. ’ Mars.— V M ho is not interested in Mars, a planet j much smaller than the earth, a little over v 4000 miles in diameter, which revolves i around the sun in somewhat less than a two years, at an average distance from the snn 50 per cent, greater than the j s earth s distance? Mars is literally one ; a of the earth’s brothers, and we should d be sincerely interested in Iris welfare. 1 e Does life exist on that planet? Almost certainly there 13 vegetable life. \Ve y have no reason to doubt it. Certain areas e of the planet change in colour as the j y climatic seasons come and go, very much ” as we should expect if these colours were controlled by the natural stages of vege- I r table life. However, in precaution, I s should guard against the drawing of the 1- conclusion that vegetable life on Mars has actually been proved to exist. I can e merely say that we see no reason to .3 doubt its existence. Is there animal life a on Mars ? There probably is. but we e have no positive evidence that such is the case. If the physical conditions on the planet as to water, air, and soil are such that vegetable life may exist, the e chances are strongly in favour of animal s life also. However. I think we must g leave unanswered for the present the ; “ question whether such animal life is 0 highly intelligent. The forests of the St. ! s Lawrence Valley and the prairies of the “ Mississippi Valley put on their green coats in the spring and changed them to ; 8 brown coats in the fall, perhaps even ’ better before the coming of man than ] t after his destructive influence descended n upon them. If you had the means to ' s ascend several thousand miles above your ; 1_ present position, and could dwell there 1 '■> throughout the year, you would witness i -- the formation of a polar snow cap upon ■ “ the earth early in the autumn. The j southern edge of this cap would extend 1 f ‘ farther and farther to the south up to : - s the time of midwinter. Its edge would j -■ extend well down toward the southern j y limits of the United States, to the Hima- j lavas in Asia, and so on. With the com- ! ■ v ing of spring the north polar cap would j y decrease in size and probably disappear, ! 8 save as to snows on the higher moun- I e tains and the -possible ice and snows of e the immediate polar region. An observer ■j similarly situated above South America ® would witness similar phenomena as to e the south polar regions; and these are indeed the phenomena observed on the planet Mars. The white polar caps on ; e Mars wax and wane with the coming and going of the winter as they do upon :s the earth. Superficially, the Martian con- I > ditions seem not very different from the g terrestrial, though we know that the : n Martian atmosphere is highly attenuated, I (1 and if we were suddenly set down upon 1 n that planet’s surface we should certainly j I, suffocate for lack of air. Water is pro- j il bably scare upon that planet in similar j ;r degree. However, these facts do not mili- j tate strongly against animal life upon j ,- that planet, for such life would undoubt- j s edly be developed with respiratory and o other organs adapted to their environ- ; s merit. A solution of the Martian pro- j e blems, as to a possible counterpart of ; e terrestrial man on that planet, is appar- ; r entlv not now hopeful ; but present-day ; e failures may be the prelude to future sue- j 1- cesses, and I prefer to offer no discourage- j ll ' men!. e The Planet Venus, — only a shade smaller than the earth, and but two-thirds as far from the sun as ■ we, presents a similar but apparently more difficult problem. Me know that ’ it has an extensive atmosphere, no doubt tj comparable with, that of the earth; but \ concern.ing the presence of water we are ; justified in making no statement other j than that we remain in apparently total ; ignorance. If Schiaparelli was right, as ; he appears to have been, that Venus . always presents the same face to the sun, j *“ just as the moon always turns the same j hemisphere toward the earth, then one ; \ hemisphere of Venus undoubtedly remains l intensely hot in perpetuity and the other c hemisphere in perpetual darkness and ex- I g cessivelv lmv temperature. Gan the twi- ‘ light zone between the hemisphere of day j ;, a fid night offer abode and comfort to liv- . ing forms, vegetable and animal? We j have found no answer to this question, and we know not liow to progress to the j . solution. r Arc the Moon and Mercury Inhabited ? ' I 1 Certainly not by such forms of life as we is art' familiar with, for neither object has j if an appreciable atmosphere. Both bodies ; : undoubtedly -offer from extremes of heat j 0 and cold, without the protecting blanket J n of atmosphere with which the earth is I h blessed. The other planets—-Jupiter, I d Saturn, Uranus, and Neptune-—may be j e dismissed as uninhabitable bv life forms j of our acquaintance. There seems no e reason to doubt that these great bodies, !’- from four to 11 times the earth in it diameter, arc still devoid of solid footing r for man or beast, such as the rock and soil strata afford upon the earth.

Other Suns than Ours.— Have astronomers been able to prove that planets revolve around other suns than ours? No, the dLtauce of the nearest stars preclude that possibility to our means in nuud. Such planets would , need to bs mauy-lold brighter than J upiter, the greatest oi our planets, and our great telescopes would need multiplication many times in diameter to let us see them as attendants to their suns. We are able to prove, and have proved, however, the existence of hundreds of bodies in distant space whose rays of light we have nut perceived. The spectrograph has shown with certainty that, of the naked-eye stars, one in four on the ax stage is not the single star which it appears to be to the naked eye, or when viewed in the telescope, but that it is a double | sun, the two bodies revolving continu- j oasiy about their mutual centre of mass. 1 These hundreds of binary systems are so | far away that even under the highest j telescopic magnification they blend into a common and essentially mathematical point. It is the expectation that the future —possibly the present centurywill establish that one star in three, on the average, is a double solar system. It may even prove to be the truth that our solar system, consisting of one great central sun and many attendant planets, is not the average and prevailing system, but is the exception and not the rule, i However, we have no good reason to j doubt, that tens of thousands —more pro- | bably tens of millions —of distant suns | ■are the centres of planetary systems, | and that countless planets are the abode j of life. As our sun is but one of millions of j suns, it is absurd and essentially incon- j eeivable that our planet, or two or three | of our planet, should be the only bodies J throughout the universe supporting life, j It is vastly more probable that if our j vision could penetrate to other stellar systems, lying in all directions from us, we should there find life in abundance, with degrees of intelligence and civilisation from which we could learn much, and with which we could sympathise. The spectroscope proves absolutely that dozens of chemical elements in the earth’s surface strata exist in the sun ; that iron, the silicon o? our rocks, hydrogen, helium, magnesium and so forth exist in the distant reaches of our stellar system. If | there is a unity of materials, unity of j laws governing those materials throughout j the universe, why may we not speculate [ somewhat confidently upon life universal ? J Comets.— In the days of my youth, here in | northern Ohio, the opinion prevailed 1 throughout the community, and widely | over the earth, that comets were the fore- j runners of wars, plagues or other forms j of dire distress. Did not the great comet I of 1811 herald the war of 1812, and that I of 1843 the Mexican War, and Donati’s ] comet of 1858 our Civil War? Even in the Twentieth Century the fear that a comet may collide with the earth and destroy its inhabitants comes to the surface here and there, every time a comet is visible to the naked eye. The findings of astronomers concerning these visitors to our region of space have taught that we have nothing to fear from them, and that their close approaches - may be welcomed, for they are interesting members of our sun's family. They revolve around our sun as the planets do, and render unto it homage and obedience. It is undoubtedly true that the earth has plunged through the tails of comets many a time and without appreciable effects upon our health and happiness. In fact, the inhabitants have at the time been blissfully unaware of the passage. It is true that a collision of the condensed head of the comet with the earth is not impossible ; it may sometime occur ; but comprehensive studies of this question, based upon observational data concerning many of these bodies, lead indubitably to tho conclusion that we must not expect those collisions to occur, on the average, more than once in 15 or 20 million years. The so-called shooting stars, which we have all observed in the night sky, are in many cases, perhaps in all. though we do not know, the burning of minute pieces of comets which have disintegrated and disappeared as comets forever from ryir sight. Colliding with the earth, rushing through the upper strata, of our atmosphere with speeds up to 40 or more miles per second, the frictional resistance of the air heats them to the burning point, and they are turned into ashes and the vapours of combustion. A very few get through to the earth’s surface and are found and placed in our museums. It is not certain that anv of those in the museums are parts of clisinleuraled counts, hut some of them probablv are. The number of small foreign bodies, which collide with our planet every day i s very .great; a conservative estimate is 20.000,000. Except for our beneficient atmosphere man would suffer many tragedies from the bombardment. There is reason to believe that the earth is growing lamer very slowly, from these accretions, and this mav have been the process bv which the earth grew from a small nuclear beginning up to its present size. Our Solar System.— Astronomers have determined that our solar system is very completely isolated in space. We are widely separated from our neighbours. I shall not try your patience by quoting the tremendous distances in miles, for they are incomprehensible to all of us. Bays of light sent out by the sun require a little more than eight minutes to reach the earth. The outermost known planet in our system, Neptune, would be reached in four hours nnd a half. Rays of light leaving the sun at the came time and travelling at the same rate. 180.000 miles per second, must travel continuously during four years and a half to reach our nearest known neighbour in space, the bright double star Alpha Centnuri. Tf lhe distance from tho sun to the earth is rue, the distance to our outer planet is 30, and the distance to

Alpha Cent: uui is 2y5,G00. There appear* to be au abundance of room in the great stellar system to inert the rejuirements ot all. the spectrograph attueiied to the Lick telescope has determined that our sun and its family of planets is travelling tnrougn the great stellar system with a speed of 12 and a half miles per second, equivalent to tour hundred million miles per w ar. Ihe earth is certainly hundreds of millions of years in age, the sun is no doubt at least as old, and the early youth of the earth was lived, not where we now are , but far elsewhere in the stellar system; and its future journeying* will lead to quite other points of observation. -.Many Problems to be .Solved,— the question of greatest interest to present-uay astronomers is that of stellar systems outer tnau our own. the chances seem strong that the hundreds of thousands 01 spiral nebulae known to exist 111 ' ais time i. juice are otiier uik! iniiependent s\>iems of star??, many or them per;taps containing as many stars as oiit stellar ryoyte-m. In other words, our stellar sy.-u.-m may lie but one of many of hundreds of thousands of isolated stellar systems distributed through endless space, 'inis is not an established fact, but the evidence seems to run in its favour. I have referred to some of the problems and results ol astronomical science. the list of interesting items is a long one, but available time has its limits, in brief it is the astronomer’s duty to discover tho Uuth about Ins surroundings in space, and make it a part of the knowledge of his day and generation, 'the ultimate and real value ol nis work lies in its influence upon the lives of the people of the world, in the changes for the better which it induces in their modes of thought, and in the impulse which it gives to an advancing civilisation. \\ ould that the attractions of the sky to t-lio average man were more potent. It is a curious comment upon the attributes of city life that hundreds of thousands of people, especially children, in London and Paris, in tile darkness which gave them semi-concealment from the enemy’s destructive airships, should have obtained their first real vision of the starry heavens. What must have been their sensations: On the other hand, those who can view its beauties and wonders are prone to neglect it; to look down instead of up. Lmerson lias said somewhere in his immortal essays that if our sky should be clear of clouds but one night in a century, the people of this globe would look forward to the rare event, and not only prepare to behold its beauties thenvelves, but make sure that their friends far and wide were likewise minded. How the beauties of the night skv would surpass the expectations of the most lively imagination. The wondrous vision would be the prevailing subject of conversation for years and years, and the repetition of the vision, 100 years later, would need no advertising. Our knowledge of the heavens is in its infancy. W e have but made a start upon the discovery of the truth about the stars, and the results of astronomical research are not so widely known amongst the people as they should be.