ASTRONOMICAL NOTES FOR MAY.

Press, Volume LXV, Issue 13410, 30 April 1909, Page 6

ASTRONOMICAL NOTES FOR MAY.

<Bt the Rev. P. W. Fairclotoh, F.R.A.S.) Jupiter is still in Leo and near to Regulus, the Lion's heart. The great planet has been retrograding for some time. That is, owing to the more irapid advance of the earth, Jupiter has been apparently thrown backwards in his path towards Regulus. On the second of the month he will be stationary, and will then begin to advance eastward. Mercury is an evening star, and will be best seen about the 20th. On the 21st he will be a little north of the new moon. At the end of fhe month Mars will rise about one in th«» morning. Rising earlier every night", he will gradually come into the evening sky from the east. Venus will pass behind the sun about the end of the month, and will slowly rise above him in the west, but will not be noticeable for a month or two. The meat conspicuous constellation is Scorpio, which can be seen in the east as soon as it is dark. The red star Antares —the false Mars —is in the head of the Scorpion. His claws stretch northward, and his long tail sweeps up and then curves down, southward. Hercules is low in the north at midniaht. Last month we discussed other-world man in a speculative way. We will now consider the habitability of what seems to be the most likely planet—« Mars. A. R. Wallace has published a

book on the question "Is Mars Habitin ble?" He is opposed to other-world , man. He champions the flatterfng yet melancholy idea that "this is the only world with intelligent lifo oh, it. Hβ may therefore be trusted to say all that can be said against the theory that the cobweb of straight lines observed on Mars are the bands of vegetation irrigated by canals constructed by intelligent beings, with water drawn from the melting of polar snows. We will state his chief objections:—

I. The surface of Mars would require to be ahnost a perfect level to admit of a network of canals in every direction. Almost all the markings aro perfectly straight and are hundreds and, in some cases, thousands of miles long. If the surface were level the wafer from the melting polar snow would Unread without canals. If it is not level, where would bo the intelligence of cutting through lulls and tablelands? These, with the water far below the surface, could not be irrigated.

2. Where is the intelligence of carrying long, straight canals through mighty deserts, instead of cultivating large contiguous districts? This is certainly a serious objection to the intelligence cf tho supposed canal builders.. If, for example, there were a large supply of water along the great Australian Bight, would it bo intelligent work to use it to cultivate straight streake across the continent in every direction, leaving desert between? Would it not be far easier and more economical of water to cultivate one large continuous region?

3. The "ca-nals," co-called, have their seasons and change colour, as if for I spring growth and harve&t. Also, it is j said that the- colour of .alleged growth J begins at the polar end of the canals, j near tho melting snow, and advances at about two jiTid a-half miles an 'hour towards the equator. Tlvis has been explained as the vegetation promoted by tho advancing stream- It implies a regular and considerable fall in tho surface from the Polos to the Equator, which seems highly improbable. This difficulty is so great that tho irrigation ists have been obliged to suggest artificial propulsion of tho water. But, again, is that possible? Further, the alleged water from the north passes over the Equator and invades the southern hemisphere to a considerable distance. In the next season the alleged water from the south similarly invades the northern hemisphere. Thus the water flows both ways! Hero again artificial propulsion is suggested. Thejudicious must surely pause before accepting such facts and such a theory.

4. According to Lowell the sol© supply of water is derived from the melting of the polar snows. Owing to the small gravitating power of the planet his snow would be three times lighter than snow on the earth. The falls of snow npjctear to be very thin. Clouds are seldom seen, yet the snowcap may bo deposited in a very short time, great increases in tho area of the cap being noticed in a single night. Sometimes the snowfall is late, and begins to melt immediately after it is deposited. It will therefore be liberal to allow 20 feet of snow, -which, being very light, will equal one foot of water. The area said to b© irrigated is at least seven times the area of the snow caps. Thie would allow less than two inches of water for irrigation—supposing none to be lost by soakage and evaporation. This inadequate supply of water certainly seems to be a serious objection to the irrigation theory, and further reflects on the intelligence of the long, straight threads of cultivation. It should be stated that the 'canals, , in order to be visible, require to be a few miles wide. One of them is 30 miles wide. Of course it is not pretended that this is the width of the watercourse. It is eaid to be the band of irrigated vegetation.

5. The atmosphere of Mars is believed to be very thin, equal to only about two inches of mercury, whereas ours is equal to 30 inches. The atmosphere of our highest mountain tops is, therefore, much denser than that on the surface of the red planet. This poverty of atmosphere must be a great disadvantage to the Martians in several ways. It cannot carry heavy cloud masses, a fact which supports the idea that the snow-caps are little more than a heavy frost. Again, a very small atmospheric pressure increase evaporation, and would lead to a heavy loss of any water that might exist. And , , again, a dense atmosphere like ours acts as a trap for the sun'e heat. Wβ live in c glass house, which stores the solnr rays. Mars receives, owing to his greater distance?, only half as much beat from the sun as the earth does. With little depth of air an<i few clouds, he can make but the poorest use of that half supply. Even ive know the- effect of Icng continued clear skies in winter. Many investigators arrive at tho conclusion that the average temperature of Mars is below freezing point. Some think that it is lower than any temperature experienced by our Antarctic heroes. If this conclusion should be made good by further research, it will be a most- serious objection to the habitability of Mars.

Mr A. R. Wallace Has his own theory to account for the "canals" of Mars as natural features. He admits that the surface is extraordinarily level—which, by the way, answers one of hh objections to the canals.' Observers have detected no mountaine. Now a world like ours, hot in the centre, must, as the centre cools and shrinks, cause- it» cruet to wrinkle and buckle up into mountains. Wallace thinks that Mars grew according to the meteoric hypothesis, by a slow aggregation of meteors, and never got hot, or cooled, as he grew. When the planet was within, say, 100 miles of his present diameter, he was cold. Then he encountered a great storm of meteoric matter, which fell so thick ands fact as to cover him with a molten eea of lava. But the centre was cold, and, as the outer coat of hot material cooled, it cracked l in long, .straight cracks. Out of these cracks, ho supposes, some heavy gas to rise, such as car%onic acid gas, and overflow, causing some kind of vegetation to grow along fhe sides.

This explanation is ingenious, but is almost as improbable as anything it is intended to explain away. The building of a cold planet is difficult enough, but the cataclysmic deluge of meteors which overlay ft with molten matter is a bold demand indeed.

"Wallace makes much of thie fact that water was not known to exist on Mars at the time he wrote—l9o7. Hβ thinks that the "snow" is frozen car-

bonic acid gas, and that the clouds, 12 or 15 miles observed on the planet's edge, are dust from .the deserts. Since he wrote the spectroscope has detected the vapour of water in tho atmosphere of Mars. This shows that the temperature is not too low for vapour, and that there is water. Clouds of dust so great and high, would also argue a considerable density cf atmosphere and strong winds, which is all against his contentions. He also argues that so cold and waterless a world could never have produced intelligent beings, and that if they were produced they would never have had the capital and resources required for such tremendous works. The canal theory, however, supposes Mars to be a slofwly dying world which, long ages ago, was well endowed «fth water. As it has cooled and its rocks have crystalieed, they have drunk v.p tho water. Tbo inhabitants, say 100,000 years ago, began to be pinched for water, and begun to build, and through aged continued t<i build canals to enable themselves to remain in their beloved countries. As the water decreased they abandoned their wide areas of cultivation, but kept main channels open a<3 a means of communication.

A planet, far advanced in cooling, would have so thick a crust that it would no longer build mountains by wrinkling. At the same time the agents of erosion would level tho ancient mountains and give the planet an even surface. This would havo taken place before the canal building began.

Between Wallace and tho canalites it seems to us that honours are even, and one must wait for further information. Perhaps come reader may be inclined to test Wallace's speculation, or rather to illustrate it, by taking a cold ball, say of iron, and dipping it in melted wax or tallow till it has a coat, say, a quarter of an inch thick. The wax must ba as cool as possible, so ac not to heat and owttind the ball. The ball should then bo suspended, set spinning slowly, and left to get thoroughly cold. The wax will probably crack. Wo would be glad to know how it cracks —in straight lines, curves, zigzags, parallels, or what-not.