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14. THE CONTROVERSY OVER THE CANALS OF MARS
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THE CONTROVERSY OVER THE CANALS OF MARS GIOVANNI SCHIAPARELLI (1835–1910) In the last quarter of the nineteenth century, a dramatic situation was developing. Astronomers had by then come to believe that few if any of the other planets in our solar system can, at least at present, support intelligent life. A possible exception was Mars, which is nearly the size of our Earth and moves in an orbit not greatly distant from the Earth’s orbit. Mars thus became the last, best hope of those who argued that, in our system, intelligent life extends beyond our Earth. Between 1877 and 1913, dozens of books, hundreds of telescopes, thousands of articles, and millions of people focused on whether intelligent beings, possibly desperately struggling to survive, conceivably seeking to signal us, roam the surface of Mars. This sensational controversy about Mars began in 1877 when Giovanni Schiaparelli , a prominent Italian astronomer, attained a result that to some constituted compelling evidence of intelligent life on Mars. This was Schiaparelli’s detection in that year of the so-called canals of Mars. In other words, he reported observing fine lines crisscrossing the Martian surface. He labeled these lines “canali,” which in Italian can mean either channel or canal, the important difference being that humans build canals whereas channels are formed by nature. As word of his reported 470 F F O O U U R R T T E E E E N N Fig. 12. Giovanni Schiaparelli [35.170.64.185] Project MUSE (2024-03-29 15:58 GMT) observations spread throughout Britain and the United States, the tendency was to call the objects “canals.” Some respected astronomers questioned Schiaparelli’s observations , whereas others supported them and in some cases reported success in observing the canals. Credulity was further tested when in 1879 Schiaparelli reported that he had seen some of the canals “geminate” or double. This typically short term appearance was both hard to understand and also to confirm. By 1890, over a dozen astronomers had reported success in sighting the canals and a few managed even to observe the elusive geminations. If Schiaparelli’s observations were difficult to accept, their potential significance and his reputation and restraint in interpreting their meaning made astronomers hesitant to dismiss them. Probably the most widely read of all Schiaparelli’s presentations of his Martian investigations was a study that he published in 1893 and that within a year appeared in English translation in a leading American journal, Astronomy and Astrophysics. The selection that follows is from that paper. Giovanni Schiaparelli, “The Planet Mars,” trans. W. H. Pickering, Astronomy and Astrophysics 13 (1894): 635–39, 717–23. Many of the first astronomers who studied Mars with the telescope , had noted on the outline of its disc two brilliant white spots of rounded form and of variable size. In process of time it was observed that whilst the ordinary spots upon Mars were displaced rapidly in consequence of its daily rotation, changing in a few hours both their position and their perspective, that the two white spots remained sensibly motionless at their posts. It was concluded rightly from this, that they must occupy the poles of rotation of the planet, or at least must be found very near to them. Consequently they were given the name of polar caps or spots. And not without reason is it conjectured, that these represent upon Mars that immense mass of snow and ice, which still to-day prevents navigators from reaching the poles of the Earth. We are led to this conclusion not only by the analogy of aspect and of place, but also by another important observation. * * * * * * * * * * * * * f r o m 1 8 6 0 t o 1 9 1 5 472 As things stand, it is manifest, that if the above mentioned white polar spots of Mars represent snow and ice, they should continue to decrease in size with the approach of summer in those places, and increase during the winter. Now this very fact is observed in the most evident manner. In the second half of the year 1892 the southern polar cap was in full view; during that interval, and especially in the months of July and August , its rapid diminution from week to week was very evident, even to those observing with common telescopes. This snow, (for we may well call it so,) which in the beginning reached as far as latitude 70°, and formed a cap of over 2000 kilometers...