Giovanni Schiaparelli was director of an observatory in Milan who carefully studied Mars in 1877 during the close approach, or opposition, of the planet. Oppositions present the most favorable opportunity for astronomers from Earth to study Mars.
Previous observers had reported appearances of streaks on the Martian surface; another Italian observer, Father Secchi, had even used the term "canali" to describe them. But Schiaparelli saw more of them and talked more about them than earlier astronomers, though he admitted that the streaks could be very hard to see. In 1878, he published an account of his observations. The similarity between the Italian word "canali," which simply means "grooves" or "channels," and the more sensational translation "canals," which implies artificial structures, led to a conception of Mars and Martians that inspired many artists, authors, and dreamers over the next century. What are the differences between this account and the one from the 1870 textbook?
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Report on Canali
By Giovanni Schiaparelli - 1877
(Italy, 1835-1910)
It is manifest that if the 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 during 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 [1240 miles] in diameter, progressively diminished, so that two or three months later little more of it remained than an area of perhaps 300 kilometers [185 miles] at the most, and still less was seen later in the last days of 1892. In these months the southern hemisphere of Mars had its summer; the summer solstice occurring upon October 13. Correspondingly the mass of snow surrounding the northern pole should have increased; but this fact was not observable, since that pole was situated in the hemisphere of Mars which was opposite to that facing the earth. The melting of the northern snow was seen in its turn in the years 1882, 1884, and 1886.
The Atmosphere:
In every climate, and under every zone, its atmosphere is nearly perpetually clear, and sufficiently transparent to permit one to recognize at any moment whatever, the contours of the seas and continents. Here and there we see appear from time to time a few whitish spots changing their position and form, rarely extending over a very wide area. It is possible that they may be layers of cloud, because the upper portions of terrestrial clouds, where they are illuminated by the Sun, appear white. But various observations lead us to think that we are dealing rather with a thin veil of fog, instead of a true nimbus cloud, carrying storms and rain. Indeed it may be merely a temporary condensation of vapor, under the form of dew or hoar frost. Accordingly, as far as we may be permitted to argue from the observed facts, the climate of Mars must resemble that of a clear day upon a high mountain. By day a very strong solar radiation hardly mitigated at all by mist or vapor, by night a copious radiation from the soil towards celestial space, and because of that a very marked refrigeration. Hence a climate of extremes, and great changes of temperature from day to night, and from one season to another.
Surface Lines:
All the vast extent of the continents is furrowed upon every side by a network of numerous lines or fine stripes of a more or less pronounced dark color whose aspect is very variable. They traverse the planet for long distances in regular lines, that do not at all resemble the winding courses of our streams. Some of the shorter ones do not reach 500 kilometers (300 miles), others extend for many thousands, occupying a quarter or sometimes even a third of a circumference of the planet. Some of these are very easy to see, especially the one designated by the name of Nilosyrtis. Others in turn are extremely difficult, and resemble the finest thread of spider's web drawn across the disk. They are subject also to great variations in their breadth, which may reach 200 or even 300 kilometers (120 to 180 miles) for the Nilosyrtis, whilst some are scarcely 30 kilometers (18 miles) broad. These lines are the famous canals of Mars. Their length and arrangement are constant, or vary only between very narrow limits. Each of them always begins and ends between the same regions. But their appearance and their degree of visibility vary greatly, for all of them, from one opposition to another, and even from one week to another often one or more become indistinct, or even wholly invisible, whilst others in their vicinity increase to the point of becoming conspicuous even in telescopes of moderate power. (Our map) shows all those that have been seen in a long series of observations. This does not at all correspond to the appearance of Mars at any given period, because generally only a few are visible at once. The canals may intersect among themselves at all possible angles, but by preference they converge towards the small spots to which we have given the names of lakes. For example, seven are seen to converge in Lacus Phoenicis, eight in Trivium Charontis, six in Lunae Lacus, and six in Ismenius Lacus.
Prominent Lines:
The two lines follow very nearly the original canal, and end in the place where it ended. One of these is often superposed as exactly upon the former linebut it also happens that both the lines may occupy opposite sides of the former canal, and be located upon entirely new ground. The distance between the two lines differs in different geminations, and varies from 600 kilometers (370 miles) and more, down to the smallest limit at which two lines may appear separated in large visual telescopes-less than an interval of 50 kilometers (30 miles).
We have already remarked that at the time of melting they appeared surrounded by a dark zone, forming a species of temporary sea. At that time the canals of the surrounding region become blacker and wider, increasing to the point of converting, at a certain time, all of the yellow region comprised between the edge of the snow and the parallel of 60¡ north latitude, into numerous islands of small extent. Such a state of things does not cease, until the snow, reduced to its minimum area, ceases to melt. Then the breadth of the canals diminishes, the temporary sea disappears, and the yellow region again returns to its former area. The different phases of these vast phenomena are renewed at each return of the seasons, and we have been able to observe them in all their particulars very easily during the oppositions of 1882, 1884, and 1886, when the planet presented its northern pole to terrestrial spectators. The most natural and the most simple interpretation is that to which we have referred, of a great inundation produced by the melting of the snows-it is entirely logical, and is sustained by evident analogy with terrestrial phenomena. We conclude therefore that the canals are such in fact, and not only in name. The network formed by these was probably determined in its origin in the geological state of the planet. It is not necessary to suppose them the work of intelligent beings, and notwithstanding the almost geometrical appearance of all of their system, we are now inclined to believe them to be produced by the evolution of the planet, just as on the earth we have the English Channel and the Channel of Mozambique.
Final Comments:
For my person I have not yet succeeded in formulating an organic whole of logical and credible thoughts about the phenomena of Mars, which are perhaps somewhat more complicated than Dr. (Svante August) Arrhenius believes. I believe with him that the lines and bands on Mars (the name "canals" should be avoided) can be explained as the results of physical and chemical forces, always excepting certain periodical color changes which are likely to be the result of organic events of large magnitude, like the flowering of the steppes on earth and similar phenomena. I am also of the opinion that the regular and geometric lines (the existence of which is still denied by many persons) do not yet teach us anything about the existence of intelligent beings on this planet. But I think it worthwhile if somebody collected everything that can reasonably be said in favor of their existence.
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