PROBLEMS OF MARS.

Dominion, Volume 2, Issue 600, 31 August 1909, Page 6

PROBLEMS OF MARS.

WILL THEY BE SOLVED NEXT MONTH? PROPOSED SIGNALLING. - •. • Mr. W. E. Raymond, . officer-in-charge, "i Sydney Laboratory, writes' as follows in the Sydney "Daily Telegraph!' Towards tho' latter part of next. month—to be moreprecise as to-time, on.September 21, at 8 p.m.—a most important astronomical pbo nomenon will take place, the, "opposition" of the planet Mars. .

Seen in the eastern sky at the present time a few hours after sunset, it has a most striking appearance—rthat of s a ball of fire— and I think it has boon: mistaken, by riiany , as "some peculiar lights in Hho heavens," and of which reports havo lately appeared in the press.. At the time of writing (August 13), Mare . is approximately 42,000,000 milesi' from us,' but getting closer some 200,000 miles eaoh day, so that on September 18. next,. when the planet will make its closest approach , to our earth, it will be _ about 35,000,000 of miles'away.. Some might ask, Should not the planet appear at its brightest on that date? Not so, for it must be understood that Mars shows phases similar to our moon, sad, although on September 18 it is at'its ' nearest to us, the earth is so plaoed in its orbit at that time that the whole of its illuminated surface is hot seen by us, and Uio appearance of the planet in good telescopes will be somewhat similar to the moon a day or two before being foil. Not natil six' days' after tho nearest approach will tho position of the earth bo sucli t&at we will see the . full phase of Mars. 1 Tho sun, earth, and Mars will then' be in line. These phases of Mars were discovered by tho great Italian astronomer, Galileo, early in the 17th contury, and they go to prove that Mari ' does not shine by its own light, but by th« . reflected light of the sun. '

iThe last opposition occurred on July 0, ; 1907, and, although Mars and the earth were in very advantageous paths of their respec- ' tive prbrts for the ( phenomenon, more re than msmy of the previous oppositions, still the coming opposition will find ' the two bodies even better placed. : . ; , • It may be as well to explain here why Mars and the earth are closer at one opposition thin' another. This k due to tho pronouiioed eccentricity of the orbit of the former. Whereas the orhii. of 'the earth is an ellipse with very little departure from the circle, tie major, and minor radii differing only 6omo 3 millions ' of miles from one another; tho difference of the two radii in the case of Mars is over 27 millions of miles,, tho minor radius 128 millions and the major 155 millions of miles. Of all the planets in , the Solar system, Mercury; has the most, ccofentrio orbit, with Mars next in order; the least in order .of . eccentricity is Venus, then, Neptune, earth,, etc. It will thus be understood that two bodies, revolving' around another body, but whoso distance : from . that,body is ndt con.' stant, will at bo mo periods of their revolu- v tions be much closer than at others.' That', is as it happens in the case of Mars and our,, earth. Tho moat favourahlo. opposition has a distance of. 35 millions of miles, the least ' favourably plaoed 61 Hence at the opposition when the planet is at the lastmentioned distance from the earth it appears', to be only half the size when at tho former.' the. ratio, I :being! 4:7 i, • , .

Is Mars Inhabited? It- is - during these oppositions that u* ,• tronomers expect to find important _ informa-. tion about our neighbour,, wnethcr -it is in a., condition'tiniilar to.our oaruh--if peopled by intelligent beings, and if they'have; customs and habits similar to our. own. ; ; ; Great preparations are being', , made by t some American astronomers to, 6igiial Mars during this;;opposition,.andall'.the. world's.-, greatest telescopes . will _be ' turned , towards the planet to , observe . if ; the Martians (if , ■ there bo-,such)' have-received those signals.,' But although disoovery may not go; as far > as' that in our day, still something, great,, may, so,-c?lled Trill; be phpfograpte- manyV tim&.■ and so have.; this ■ important' mattery settled beyond . all doubt'./,, Other- natural features' of Maris ill.;also, receivgjtbeir. proper jwrtiori of attention,-, : and ,'we iiviy arrive?'at some definite conchiEi"ion .. 'as to distribuUbn'.o'f.Jand, and .'.water. on tbo ,'plah^t.'! ' At the.'present time .it. is", f)re-.V sumed that very little water exists 011 Mara... practically .' the only supplybeing derived ~ from-, the melting of the snow at the polea. The! peculiar colour of this planet is probably due to the ruddy nature of the 50i1.,.

About the Canals. Mora canals wore first discovered by the Italian" 1 astronomer Schiaparelli,; in the year 1877, and were called' canali, or channels, by i him, and .he made .further observations oil several subsequent occasions until failing sight 'put. a stop to'bis great work in the year 1890. To"' Italy is thus.due .this great • discoveries of tHe'phases. and canals of Marsi ■: Of recent.astronomers, Professors Picker- ', ing and ixiwell, the former at.' Harvard; Col-;:• lego' Observatory,. U.S.A., and the latter at the observatory, Flagstaff, Arizona, U.S.A-, ; have given much of their time to unravellitis • the mysteries of • Mars. Professor Pidcering was the discoverer of tho many spots: connected ,with 7 the ' canal system;.';: . which' may be gteat works,- of, water conservation,. and* Professor LoweH, from hisv observatory,' iiad ; photographs' .obtained • by v. Mr, Lamplands, snowing the . canal system'--during .the opposition in 1905. , tronomer practically makes; a .'..speciality ■ • of- - ' .Mars study,. and is, perhaps, the world's ; greatest' authority on tlie planet. , Mars revolves on jts ; axis almost in : tho': same time as' the earth, taking' only \4O- - inoro for the revolution,; but its year - consists of 687 of our .days, or, 669 of itsyown, It travels around its orbit at. n. speed-', slower than tho .oarth, the rate v beilig 15 lt : . miles against 18i miles per second. Other; resemblances between the two planets., are' •tho' tilt of their equators 'to tlio. piano of ', their orbits, so thai similar, seasons .prevail . oil both. . They are, of course,' longer , on: Mars, as the Martian year- is nearly . twico as long as tbo-terrestrial year; and, o\ving v < to. tho eccentricity of Mars orbit previously described, the seasons. are not. ' of, equal: length. As 'summer approaches .; on!v tbo planet. tho, snow at the poles thaw and • the i snow, caps greatly decreaso in siws, expand- 1 . ing; again on the approach of the winter seaSon. It also possesses an. atmosphere simi- 1 lar to. tho earth, for occasionally the markings on its surface are observed by' patches of cloud. . ■■■■■■;. ' '

Our amateur asttcooDiors should not Jet this opposition' pass without pro-;... viding favourable weather prevails, and ire.; may.-expect something good- from zealous :• workers. To those who .liavo sketching • ability they , should make drawings of .tho - planet as. they-.seo it in their 'telescopes, if ' possible colour drawings. .During previous/ oppositions, Mr.- G. H. Hirst, a member of the New South AVales branch of. the British,'' Astronomical Association, made some very !<. perfect sketches of liars. Oil September. 24 next, others should follow '..liis example, / and it would be very interesting, to them to compare their. work - with the .'photographs/-. which will ultimately appftir in the s'cieu- ' tilic journals. To those who. have a penchant for observing a very complete list of•' stars appears-in the Nautical Almanac for ' 1909, and they could" profitably devote tlieif time to this observing' in order to delepi:/; mine the parallax of the planet.