Arizona republican., 1895-02-02
THE WEATHER ON MARS.
Visible Evidences of @ Warm
 Spell on the Planet.
An Extensive Thaw Observed Which In dicated Summer Season in the Southern Hemisphere of Our
 NeighboriDg World.

Among the most interesting observa- tions of Mars during the recent opposi- tion were those relating to the gradual disappearance of the snow cap sur rounding it's southern pole. The disap- pearance was due of course, to the fact that it was summer in the south ern hemisphere of Mars, and the polar SHOWS melted more and more rapidly as the sun rose higher upon them. Yet, although the reason was plain, and be- cause it was plain, one could not watch the process without experiencing strange feeling that amounted almost to awe. It is quite easy, says the Sci entifc American, to think dispassion- ately of the possibility that some things may gG on in other worlds just as they do in this one as long as your eyes have not confirmed what IS in your mind; but when peering througha telescope you actually behold such occurrences, the effect is startling. It is like com ing suddenly in broad daylight upon the scenery of a dream. On June 1 the snow around the south pole of Mars was 2, 400 miles across. A snow cap of proportionate dimensions on the earth would, in the northern hemisphere, ex- tend as far south as St. Petersburg, the southern point of Greenland and Mount St. Elias in Alaska. By July 1 the di- ameter of the snowy area had dimin- ished to about 1.500 miles. On August 1 it was only HOO miles and on August 31, the date of the summer solstice in the southern hemisphere of Mars, the snow cap was but 800 miles across. But heat accumulates in Martian summer after the sun has begun to decline, just as it does upon the earth, and accord ingly the melting of the snows contin- ued after the solstice was passed. At the end of September the diameter of the snow-covered region was only about $50 miles, and at the opening of Novem- Der it was less than 200 miles.
 Now comes a curious fact. About the middle of October it was reported that the polar snow cap of Mars had van ished; some of the most powerful tele- scopes failed to reveal a trace of it! Yet it is not probable that it had actual ly entirely disappeared. The explana- tion of the apparent disappearance is no doubt to be found in the fact that as the snow area diminished it left the pole uncovered by receding to one side. for previous observations have shown that on Mars, as on the earth, what may be called the pole of cold does not correspond in location with the pole of the planets axis. Schiaparelli's observations in 1877 and 1879 showed that the center of the snow cap during its minimum in those years was dis placed toward that side of the pole corresponding to an areographic longi tude of about 40 degrees. With the other side of the planet turned toward the earth the snow cap would have been invisible, being, so tt to speak, hidden behind the pole. Thi
 is apparently just what occurred in the. middle of October last. Int south pole was then free from ice, ant the center of the snowy region wa
 displaced, as in 1877 and 1879, along thu meridian of 40 degrees. But it was o1 the other side of the planet which wa at that time presented toward tn
 earth during the best hours for obser vation, and consequently no polar snoV was seen; not because it had no exist ence, but because it was concealed.
 It is probable, however, that at it minimum the snow cap was exceeding ly small, perhaps less than one hundre' miles in diameter. No such rapid an
 and extensive disappearance of snov and ice ever occurs upon the earth, d though the advocates of an open pola sea may find encouragement in tn fact that the uncovered south pole c Mars corresponds in color and genera appearance with what are believed t be the water areas of that planet, whil what remains of the snow cap in sue