TEMPERATURE OF MARS.

Hawera Star, Volume XLVIII, 11 February 1925, Page 4

TEMPERATURE OF MARS.

A HABITABLE WORLD

WARM ENOUGH FOR LIFE TO EXIST. For years past the problem of the temperature of the planet Marg has been recognised as one of the key problems of planetary astronomy, writes the Astronomical Correspondent of the Manchester Guardian. Quite obviously, it has a real bearing on the vexed question of the habitability ,>f our neighbour world. For there are .crtain limits of temperature within which alone life, or anything analogous to what wc know as life, can exist; and evidently, if the temperature of Mars should be definitely known to be outside of the lower of these limits, all speculation as to the hypothetical Martians is besiclc the mark. “Vital phenomena,” as Dr. Alfred Russel Wallace pointed out twenty years ago, “for the most part occur between the temperature of freezing water and 104 degrees Fahrenheit, and this is supposed to be due mainly to the properties of nitrogen and its compounds, which between these temperatures only can maintain those peculiarities which are essential to life—extreme sensitiveness, facility ef chancre as regards chemical combination and energy, and other properties which alone render nuitrition. growth, and continual repair possible. A very email increase or decrease of temperature beyond these limits, if continued for anv considerable time, would destroy most existing forms o'" life and would not improbably render anv further development of life impossible except in some of its lowest forms.”

NOT A FROZEN WORLD. Mr. Maunder and other astronomers, on theoretical grounds, agreed with Dr. Wallace that the surface temperature of Mars is considerably below the freez-ing-point of water. This conclusion is reached by a. simple calculation. Conn paring the distance of Mars from the sun with the distance of the earth, the intensity of solar radiation on the Mortian surface comes out at about three-sevenths of the intensity of our own world. But this conclusion was always stoutly contested bv those astronomers. such as Schiaparelli, AY. W. H. Pickering, Lowell, E. C. Slipher. and others, who have specialised in Martian astronomy; Evidently the planet which the astronomer observes through the telescope is not a frozen world. There are frozen regions, certainly, round the poles. But these white caps shrink under the rays of the sun ’in suninier seasons, a'nd a broad blue belt is invariably observed surrounding the melting cap, which is almost certainly an open polar sea. Again, the astronomer observes t\*e growth and decay of vegetation, while ■fogs, mists and clouds are frequently recorded. Ingenious methods have been made from time to time to explain away the appearance of the polar caps by the hyothesis that thev are composed of frozen carbonic acid gas. But this hvpothesis was discredited years ago. Besides, apart from the caps, the appearance of the planet is altogether against tlie low temperature theory. Lowell and Pickering have shown in recent years that other factors than distance from the sun have to he taken into account in estimating the Martian temperature. Lowell showed that “the clearness of the Martian sky comes in to abet the greater transmission of its air. From dawn till dusk, day after day .in the summer season, and largely in winter, the sun shines out of a heaven innocent of cloud. No shield of the sort and only n little screen of air temnres its beams to the soil held up to it. Such an exposure far exceeds anything we have on earth; for with us. even in the tropics, clouds gather as sonn as the beating grows excessive and cool the air by plumps of rain. And Picker, ing has drawn attention to the cloudiness of the nights on Mars, which prevent the escape of the heat received during the day. What is remarbable, then, is not the camparatively limb temperature of Mars, but the coinnarativelv low temperature of the earth. Pickering computed the tem-oo’-ature to be 32 degrees Fahrenheit •■'•hen the snows were melting; Lowell ‘‘onnrl 4S degrees Fahrenheit to be tlie mean temperature of the planet. That >->F the earth he said, is GO degrees Fahrenheit, “so that the mean climatic wa-mth of the two planets it not very unlike and far within the possibilities of life for both.” “THE TEMERATURE OF A COOL BRIGHT DAY ON EARTH.” Over twenty years ago the late Professor Young said, “It is earnestly to be hoped that before very long we may come into possession of some beat measures sufficiently delicate to give us direct evidence as to the warmth or coldness of the planet’s surface.” This hope has been realised, and Messrs C. O. Lampland and W. W. Ooblentz, of the Lowell Observatory, have just announced the results of their investigations with the radiometer attached to the 40-inch reflector. These investigations were commenced in 1922 and have been continued during the present favourable opposition of the planet. Radiometric measurements were made of different regions of the surface, such as the polar and equatorial regions, and of the same regions at different hours of the day. The measures show that tlie equatorial regions, as is to he expected, are much warmer than the poles, that the afternoon temperature is higher than the morning, that the blue-green areas are wanner than the reddish-ochre regions, and that in the southern hemisphere, where summer has been advancing there has been a steady rise in mean temperature. “The measurements.” says Messrs Lampland and Cohlentz, “indicate that the temperature of the brightlv illuminated surface of Mars is not unlike that of a cool, bright day on this earth, with temperature ranging hnm 7dcg to 18deg. C. or 45deg to (35deg F.” He-" vn have conclusive evidence that Professors Towell and Pickering and the experts who have specialised in the study o f Mar* li*"" been right, and that Dr 'Wallace, Mr. Maunder and the large number of astronomers who R""eed with them have been wrong. S*-ong snpoort has been given to the view that Mars is a habitable world.