SOLAR DISTURBANCES.

New Zealand Herald, Volume LVI, Issue 17337, 8 December 1919, Page 9

SOLAR DISTURBANCES.

PLANETS AND THE EARTH. POSITION ON DECEMBER 17. "NO NEED FOR ALARM." ] Considerable interest has been aroused in Auckland by predictions of serious weather and other disturbances on December 17 next. In an article in the Christ- . church Press, Mr. E. G. Hogg, M.A., ✓ F.R.A.S., says :— Professor Porta, an American solar physicist, has drawn some disturbing conclusions frota the fact that on December 17 , there will be a somewhat unusual distribution of the planets relative to the sun, "A gigantic explosion of flaming I gases," due to a' great sunspot, will, he predicts, cause "terrific storms" on the earth. Certainly, to an observer placed on the sun, the planets would present an interesting spectacle, as most of them would appear in the same general direction in the heavens, but why Mr. Clement L. Wragge, who evidently takes the whole matter seriously, should regard this as "very ominous and significant," is by no means clear. His language recalls the good old days when the astrologer, by careful manipulation of planets benign and planets malign, gained for himself a dismal notoriety and a precarious income. Gravitative Pull of Planets. It may be interesting to try to get at the root of Professor Porta's prediction, but it may be as well to say at the outset that such general conjunctions as will occur about December 17 have happened on innumerable occasions before, and, so far as our information goes, without any noticeable effect on the earth, while minor conjunctions are among the commonest of astronomical phenomena. Let us assume, then, that all the planets are in a line with the sun, with Mercury nearest, and Neptune at the greatest distance from the sun; things will not be quite as bad as this on the 17th — fact, the earth will not nearly be pulling her proper weight oil the day in question. The only way in which the planets, so far as we know, can affect the sun, is by their gravitative pull, and this will be most effective when they are aligned as assumed above. > We all know the small amount of tide — ■ due to the moon—which is experienced in the open ocean; the tide caused by the l sun is far smaller than the lunar" tide. Let us see what the planets most effective ; in raising tides in the sun can these . planets are Venus, Mercury, and Jupiter. The tide-raising power of the first-named

planet is only about 1-750 of that which the sun exerts on the earth, -while the powers of Mercury and Jupiter are each about 1-1000 of the sun's influence on the earth. Hence, making all allowances for the extreme rarity of the materials which compose the solar atmosphere, it seems most unlikely that even if all planets were palling together they ceuld originate any I appreciable disturbance in the sun's outer parts. The fleet of Sun Spots. Professor Porta appears to rely largely on "a great sun-spot." The sum's surface is liable to periodic outbreaks of great violence, when millions of square miles of the surface are affected by gigantic storms, somewhat of the nature of whirlpools. From a state of relative quiescence the solar surface will gradually pass into a state of great activity, which will slowly decline until the former state of rest is attained, when a new cycle of activity will begin. The records of the numbers of sun spots show that the interval of time between two maxima of activity is about 11 years. At present the sun is in a moderately disturbed state ; the last maximum occurred in 1917, and the sun is proceeding in due course to a minimum. Hence it is by no means unlikely that on or about the 17th inst. there may be a sun spot of more or less magnitude visible on the sun, but it by no means follows that the sun spot will be caused by the combined attraction of the planets. Of the origin of sun spots very little is known ; many attempts have been made to connect the solar storms with .the positions of the planets relative to the sun, but up ' to the present no theory which attributes sun spots directly to the gravitating influence of the planets has. successfully withstood close examination.

Spots Frequently Seen. £ Let us, however., grant Professor Porta a lis sun spot; why should it cause "terrific 11 storms" on tire earth? All evidence is T igainst the view that maxima of sun-spot ! *- ictivity are times of violent storms on the • 4 sarth; meteorological data are thought by | t some to yield evidence of a thirty-five-year £ period in terrestrial weather conditions, ® but even if this were true, the time for t meteorological disturbances on an aggravated scale is not due until 1925. If the case is weak against the connection between earth storms and sun-spot maxima, it is hopeless to. predict -what may happen i from a single spot. Times without number j lias a spot appeared on the eastern limb of the sun, been visible during thirteen ! days, while the sun's rotation has apparently carried it across the solar disc to ' the western limb, when it has disappeared I — turn up again perhaps thirteen days later on the eastern limband all Che while ! nothing particular has happened on the earth. ' Here we must leave Professor Porta; ' we see no cause for alarm in his or in Mr. Wragge's predictions. There is, it is * true, some connection between sun spots - and magnetic storms on the earth, though ! what the link is we do not clearly under- ( stand. 1 All we can hope for, then, is that on 1 , the night of the 17th Professor Porta'si ■ sun spot will rise to the occasion and let 1 us have, if not a magnetic storm—which 1 we should not hear of until the next day 1 but some auroral manifestation which ! exultant voters may be pleased to regard : as evidence of the genial interest oirr ■ luminary takes in our little political affairs. ; MR. WRAGGE'S PREDICTIONS. A PERSONAL EXPLANATION. Mr. Clement Wragge writes as follows : — "I am a. public scientific man, and I am endeavouring most truly to do my very best in my own line of work for everybody. Through your kindness, then, I do very earnestly ask the people, not to believe the many extraordinary and ridiculous reports that are current throughout this Dominion anent my weather forecasts and advices. Only this morning have I received a letter from a person living within 100 miles from Tolago Bay to the effect that I had predicted from three to 11 years drought. Needless to say. such a prophecy never entered my mind. "Every word of my forecasts is most carefully weighed and considered with the nicest judgment possible to the human brain, and nothing herein is genuine unless signed by me or published by the reputable press, such as the New Zealand Herald, Auckland Wejekj.y News, and others in the Dominion. That I may make occasional mistakes is fully admitted, since I am not a chronometric automaton, but only human, and liable to errors of personal equation and judgment like the best of us. Any way, I have the satisfaction of knowing that I do the best of which I am capable. "Anent the configurations of the sun and planets this month I am no sensationmonger. I simply gave the mathematical figures, and suggested what might or might I not occur here; and what I have given out was from a sterling sense of duty. i "Thus nothing whatever may occur in New Zealand, and if people will only use the most common prudence at this time there is not the slightest need to lose sleep unless to view the Aurora Australis, which may or may not take place. So God's own country, of which I am so very proud to he a citizen, may safely go' on its way. and rejoice in a thoroughly sound and statesmanlike ' •ovcrnmen't. I beg you will do Sue the juetioe of inserting this letter."