Astronomical Curiosities: Facts and Fallacies. Gore John Ellard

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СКАЧАТЬ the great physicist, Arrhenius, says —

      “We often hear lamentation that the coal stored up in the earth is wasted by the present generation without any thought of the future, and we are terrified by the awful destruction of life and property which has followed the volcanic eruptions of our days. We may find a kind of consolation in the consideration that here, as in every other case, there is good mixed with evil. By the influence of the increasing percentage of carbonic acid in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind.”74

      The night of July 1, 1908, was unusually bright. This was noticed in various parts of England and Ireland, and by the present writer in Dublin. Humboldt states that “at the time of the new moon at midnight in 1743, the phosphorescence was so intense that objects could be distinctly recognized at a distance of more than 600 feet.”75

      An interesting proof of the earth’s rotation on its axis has recently been found.

      “In a paper in the Proceedings of the Vienna Academy (June, 1908) by Herr Tumlirz, it is shown mathematically that if a liquid is flowing outwards between two horizontal discs, the lines of flow will be strictly straight only if the discs and vessel be at rest, and will assume certain curves if that vessel and the discs are in rotation, as, for example, due to the earth’s rotation. An experimental arrangement was set up with all precautions, and the stream lines were marked with coloured liquids and photographed. These were in general accord with the predictions of theory and the supposition that the earth is rotating about an axis.”76

      In a book published in 1905 entitled The Rational Almanac, by Moses B. Cotsworth, of York, the author states that (p. 397), “The explanation is apparent from the Great Pyramid’s Slope, which conclusively proves that when it was built the latitude of that region was 7°·1 more than at present. Egyptian Memphis now near Cairo was then in latitude 37°·1, where Asia Minor now ranges, whilst Syria would then be where the Caucasus regions now experience those rigorous winters formerly experienced in Syria.” But the reality of this comparatively great change of latitude in the position of the Great Pyramid can be easily disproved. Pytheas of Marseilles – who lived in the time of Alexander the Great, about 330 B.C. – measured the latitude of Marseilles by means of a gnomon, and found it to be about 42° 56′½. As the present latitude of Marseilles is 43° 17′ 50″, no great change in the latitude could have taken place in over 2000 years.77 From this we may conclude that the latitude of the Great Pyramid has not changed by 7°·1 since its construction. There is, it is true, a slow diminution going on in the obliquity of the ecliptic (or inclination of the earth’s axis), but modern observations show that this would not amount to as much as one degree in 6000 years. Eudemus of Rhodes – a disciple of Aristotle (who died in 322 B.C.) – found the obliquity of the ecliptic to be 24°, which differs but little from its present value, 23° 27′. Al-Sufi in the tenth century measured the latitude of Schiraz in Persia, and found it 29° 36′. Its present latitude is 29° 36′ 30″,78 so that evidently there has been no change in the latitude in 900 years.

       CHAPTER V

      The Moon

      The total area of the moon’s surface is about equal to that of North and South America. The actual surface visible at any one time is about equal to North America.

      The famous lunar observer, Schröter, thought that the moon had an atmosphere, but estimated its height at only a little over a mile. Its density he supposed to be less than that of the vacuum in an air-pump. Recent investigations, however, seem to show that owing to its small mass and attractive force the moon could not retain an atmosphere like that of the earth.

      Prof. N. S. Shaler, of Harvard (U.S.A.), finds from a study of the moon (from a geological point of view) with the 15-inch refractor of the Harvard Observatory, that our satellite has no atmosphere nor any form of organic life, and he believes that its surface “was brought to its present condition before the earth had even a solid crust.”79

      There is a curious illusion with reference to the moon’s apparent diameter referred to by Proctor.80 If, when the moon is absent in the winter months, we ask a person whether the moon’s diameter is greater or less than the distance between the stars δ and ε, and ε and ζ Orionis, the three well-known stars in the “belt of Orion,” the answer will probably be that the moon’s apparent diameter is about equal to each of these distances. But in reality the apparent distance between δ and ε Orionis (or between ε and ζ, which is about the same) is more than double the moon’s apparent diameter. This seems at first sight a startling statement; but its truth is, of course, beyond all doubt and is not open to argument. Proctor points out that if a person estimates the moon as a foot in diameter, as its apparent diameter is about half a degree, this would imply that the observer estimates the circumference of the star sphere as about 720 feet (360° × 2), and hence the radius (or the moon’s distance from the earth) about 115 feet. But in reality all such estimates have no scientific (that is, accurate) meaning. Some of the ancients, such as Aristotle, Cicero, and Heraclitus, seem to have estimated the moon’s apparent diameter at about a foot.81 This shows that even great minds may make serious mistakes.

      It has been stated by some writer that the moon as seen with the highest powers of the great Yerkes telescope (40 inches aperture) appears “just as it would be seen with the naked eye if it were suspended 60 miles over our heads.” But this statement is quite erroneous. The moon as seen with the naked eye or with a telescope shows us nearly a whole hemisphere of its surface. But if the eye were placed only 60 miles from the moon’s surface, we should see only a small portion of its surface. In fact, it is a curious paradox that the nearer the eye is to a sphere the less we see of its surface! The truth of this will be evident from the fact that on a level plain an eye placed at a height, say 5 feet, sees a very small portion indeed of the earth’s surface, and the higher we ascend the more of the surface we see. I find that at a distance of 60 miles from the moon’s surface we should only see a small portion of its visible hemisphere (about 1⁄90th). The lunar features would also appear under a different aspect. The view would be more of a landscape than that seen in any telescope. This view of the matter is not new. It has been previously pointed out, especially by M. Flammarion and Mr. Whitmell, but its truth is not, I think, generally recognized. Prof. Newcomb doubts whether with any telescope the moon has ever been seen so well as it would be if brought within 500 miles of the earth.

      A relief map of the moon 19 feet in diameter was added, in 1898, to the Field Columbian Museum (U.S.A.). It was prepared with great care from the lunar charts of Beer and Mädler, and Dr. Schmidt of the Athens Observatory, and it shows the lunar features very accurately. Its construction took five years.

      On a photograph of a part of the moon’s surface near the crater Eratosthenes, Prof. William H. Pickering finds markings which very much resemble the so-called “canals” of Mars. The photograph was taken in Jamaica, and a copy of it is given in Prof. Pickering’s book on the Moon, and in Popular Astronomy, February, 1904.

      Experiments made in America by Messrs. Stebbins and F. C. Brown, by means of selenium cells, show that the light of the full moon is about nine times that of the half moon;82 and that “the moon is brighter between the first quarter and full than in the corresponding phase after full moon.” They also find that the light of the full moon is equal to “0·23 candle power,”СКАЧАТЬ