| Show IS THE SUN GROWING COLD we want to know whether chesun is showing any symptoms of decay says bays the story of the Ji heavens eavens are the days as warm and bright as they were ten years ago one hundred years year sago ago we can find no evidence of any change since the beginning of authentic records if the suns suna heat beat had perceptibly changed within the last 2000 deais we should expect to find corresponding changes in the distribution of plants and animals but no such changes abang es have been detected there is no reason to think that the climate of ancient greece or ancient rome borne was appreciably differ ent from the climates of the greece and the rome that we know at this day the vine and olive now grow where they grow grew 2000 years ago I 1 we must not however lay too much stress on this argument for the effects ot of slight changes in the suns sun s heat beat may have been neutral teed i or in the pliable organisms of cultivated plants all we can certainly cou conclude clude is that no marked change has taken place in the heat of the sun luring during historical time but when we come to look back into the vastly earlier ages we find the most copious evidence that the earth has u undergone great greate changes hauges in climate geological records cau can on this question hardly be misinterpreted yet it is ir custom to note that these changes are hardly such as could arise from the gradual exhaustion of the suns radiation no doubt in very early limes we have evidence ti eliat bat the earths cli climate m must have been much warmer than now we had the great carboniferous epoch when the temperature must almost have been tropical in arctic latitudes yet it is hardly possible to cite this as evidence that the sun was then much more powerful for we are immediately reminded of the glacial epoch when our temperate zones were encased iu in sheets of solid lee ice as no northern ethern greenland is at present if we suppose the sun to have been hotter than it is at present to account for the vegetation which produced coal then we ought to assume the sun to be colder than it is now to account for reasonable to attribute such phenomena to such auch oscillations in the radiation from the sun the glacial epochs prove that we can not appeal to geology in aid of the doctrine that a secular cooling of the sun is now in progress the geological variations of climate may have been caused by changes in the earth itself by changes in the position of its axis by changes in its actual orbit but however they have been caused they hardly tell us much with regard to the previous history of the sun the heat beat of the sun has lasted for countless ages yet we cannot credit the sun with the power of of actually creating heat we must apply even to the majestic mass of the sun the same laws which we have found by our experiments on the earth we mutt must ask whence comes the heat beat sufficient to supply this tremendous outgoing |
