Astronomical Curiosities: Facts and Fallacies

Many attempts have been made by “paradoxers” to show that the earth is a flat plane and not a sphere. But M. Ricco has found by actual experiment that the reflected image of the setting sun from a smooth sea is an elongated ellipse. This proves mathematically beyond all doubt that the surface of the sea is spherical; for the reflection from a plane surface would be necessarily circular. The theory of a “flat earth” is therefore proved to be quite untenable, and all the arguments (?) of the “earth flatteners” have now been – like the French Revolution – “blown into space.”

The pole of minimum temperature in the northern hemisphere, or “the pole of cold,” as it has been termed, is supposed to lie near Werchojansk in Siberia, where a temperature of nearly -70° has been observed.

From a series of observations made at Annapolis (U.S.A.) on the gradual disappearance of the blue of the sky after sunset, Dr. See finds that the extreme height of the earth’s atmosphere is about 130 miles. Prof. Newcomb finds that meteors first appear at a mean height of about 74 miles.[56 - Bulletin, Ast. Soc. de France, August, 1905.]

An aurora seen in Canada on July 15, 1893, was observed from stations 110 miles apart, and from these observations the aurora was found to lie at a height of 166 miles above the earth’s surface. It was computed that if the auroral “arch maintained an equal height above the earth its ends were 1150 miles away, so that the magnificent sight was presented of an auroral belt in the sky with 2300 miles between its two extremities.”[57 - Nature, April 5, 1894.]

“Luminous clouds” are bright clouds sometimes seen at night near the end of June and beginning of July. They appear above the northern horizon over the sun’s place about midnight, and evidently lie at a great height above the earth’s surface. Observations made in Germany by Dr. Jesse, and in England by Mr. Backhouse, in the years 1885-91, show that the height of these clouds is nearly constant at about 51 miles.[58 - Nature, May 14, 1896. Some have attributed these “luminous clouds” to light reflected from the dust of the Krakatoa eruption (1883).] The present writer has seen these remarkable clouds on one or two occasions in County Sligo, Ireland, during the period above mentioned.

M. Montigny has shown that “the approach of violent cyclones or other storms is heralded by an increase of scintillation” (or twinkling of the stars). The effect is also very evident when such storms pass at a considerable distance. He has also made some interesting observations (especially on the star Capella), which show that, not only does scintillation increase in rainy weather, but that “it is very evident, at such times, in stars situated at an altitude at which on other occasions it would not be perceptible at all; thus confirming the remark of Humboldt’s with regard to the advent of the wet season in tropical countries.”[59 - The Observatory, 1877, p. 90.]

In a paper on the subject of “Optical Illusions” in Popular Astronomy, February, 1906, Mr. Arthur K. Bartlett, of Batter Creek, Michigan (U.S.A.), makes the following interesting remarks: —

“The lunar halo which by many persons is regarded as a remarkable and unexplained luminosity associated with the moon, is to meteorological students neither a mysterious nor an anomalous occurrence. It has been frequently observed and for many years thoroughly understood, and at the present time admits of an easy scientific explanation. It is an atmospheric exhibition due to the refraction and dispersion of the moon’s light through very minute ice crystals floating at great elevations above the earth, and it is explained by the science of meteorology, to which it properly belongs; for it is not of cosmical origin, and in no way pertains to astronomy, as most persons suppose, except as it depends on the moon, whose light passing through the atmosphere, produces the luminous halo, which as will be seen, is simply an optical illusion, originating, not in the vicinity of the moon – two hundred and forty thousand miles away – but just above the earth’s surface, and within the aqueous envelope that surrounds it on all sides… A halo may form round the sun as well as the moon … but a halo is more frequently noticed round the moon for the reason that we are too much dazzled by the sun’s light to distinguish faint colours surrounding its disc, and to see them it is necessary to look through smoked glass, or view the sun by reflection from the surface of still water, by which its brilliancy is very much reduced.”…

“A ‘corona’ is an appearance of faintly coloured rings often seen around the sun and moon when a light fleecy cloud passes over them, and should not be mistaken for a halo, which is much larger and more complicated in its structure. These two phenomena are frequently confounded by inexperienced observers.” With these remarks the present writer fully concurs.

Mr. Bartlett adds —

“As a halo is never seen except when the sky is hazy, it indicates that moisture is accumulating in the atmosphere which will form clouds, and usually result in a storm. But the popular notion that the number of bright stars visible within the circle indicates the number of days before the storm will occur, is without any foundation whatever, and the belief is almost too absurd to be refuted. In whatever part of the sky a lunar halo is seen, one or more bright stars are always sure to be noticed inside the luminous ring, and the number visible depends entirely upon the position of the moon. Moreover, when the sky within the circle is examined with even a small telescope, hundreds of stars are visible where only one, or perhaps two or three, are perceived with the naked eye.”

It is possible to have five Sundays in February (the year must of course be a “leap year”). This occurred in the year 1880, Sunday falling on February 1, 8, 15, 22, and 29. But this will not happen again till the year 1920. No century year (such as 1900, 2000, etc.) could possibly have five Sundays in February, and the Rev. Richard Campbell, who investigated this matter, finds the following sequence of years in which five Sundays occur in February: 1604, 1632, 1660, 1688, 1728, 1756, 1784, 1824, 1852, 1880, 1920, 1948, 1976.[60 - Popular Astronomy, vol. 11 (1903), p. 293.]

In an article on “The Last Day and Year of the Century: Remarks on Time Reckoning,” in Nature, September 10, 1896, Mr. W. T. Lynn, the eminent astronomer, says, “The late Astronomer Royal, Sir George Airy, once received a letter requesting him to settle a dispute which had arisen in some local debating society, as to which would be the first day of the next century. His reply was, ‘A very little consideration will suffice to show that the first day of the twentieth century will be January 1, 1901.’ Simple as the matter seems, the fact that it is occasionally brought into question shows that there is some little difficulty connected with it. Probably, however, this is in a great measure due to the circumstance that the actual figures are changed on January 1, 1900, the day preceding being December 31, 1899. A century is a very definite word for an interval respecting which there is no possible room for mistake or difference of opinion. But the date of its ending depends upon that of its beginning. Our double system of backward and forward reckoning leads to a good deal of inconvenience. Our reckoning supposes (what we know was not the case, but as an era the date does equally well) that Christ was born at the end of B.C. 1. At the end of A.D. 1, therefore, one year had elapsed from the event, at the end of A.D. 100, one century, and at the end of 1900, nineteen centuries… It is clear, then, that the year, as we call it, is an ordinal number, and that 1900 years from the birth of Christ (reckoning as we do from B.C. 1) will not be completed until the end of December 31 in that year, the twentieth century beginning with January 1, 1901, that is (to be exact) at the previous midnight, when the day commences by civil reckoning.” With these remarks of Mr. Lynn I fully concur, and, so far as I know, all astronomers agree with him. As the discussion will probably again arise at the end of the twentieth century, I would like to put on record here what the scientific opinion was at the close of the nineteenth century.

Prof. E. Rutherford, the well-known authority on radium, suggests that possibly radium is a source of heat from within the earth. Traces of radium have been detected in many rocks and soils, and even in sea water. Calculation shows that the total amount distributed through the earth’s crust is enormously large, although relatively small “compared with the annual output of coal for the world.” The amount of radium necessary to compensate for the present loss of heat from the earth “corresponds to only five parts in one hundred million millions per unit mass,” and the “observations of Elster and Gertel show that the radio-activity observed in soils corresponds to the presence of about this proportion of radium.”[61 - Popular Astronomy, vol. 13 (1905), p. 226.]

The earth has 12 different motions. These are as follows: —

1. Rotation on its axis, having a period of 24 hours.

2. Revolution round the sun; period 365¼ days.

3. Precession; period of about 25,765 years.

4. Semi-lunar gravitation; period 28 days.

5. Nutation; period 18½ years.

6. Variation in obliquity of the ecliptic; about 47″ in 100 years.

7. Variation of eccentricity of orbit.

8. Change of line of apsides; period about 21,000 years.

9. Planetary perturbations.

10. Change of centre of gravity of whole solar system.

11. General motion of solar system in space.

12. Variation of latitude with several degrees of periodicity.[62 - Nature, July 25, 1901 (from Flammarion).]

“An amusing story has been told which affords a good illustration of the ignorance and popular notions regarding the tides prevailing even among persons of average intelligence. ‘Tell me,’ said a man to an eminent living English astronomer not long ago, ‘is it still considered probable that the tides are caused by the moon?’ The man of science replied that to the best of his belief it was, and then asked in turn whether the inquirer had any serious reason for questioning the relationship. ‘Well, I don’t know,’ was the answer; ‘sometimes when there is no moon there seems to be a tide all the same.’”![63 - Popular Astronomy, vol. 11 (1903), p. 496.]

With reference to the force of gravitation, on the earth and other bodies in the universe, Mr. William B. Taylor has well said, “With each revolving year new demonstrations of its absolute precision and of its universal domination serves only to fill the mind with added wonder and with added confidence in the stability and the supremacy of the power in which has been found no variableness neither shadow of turning, but which – the same yesterday, to-day and for ever —

“Lives through all life, extends through all extent,
Spreads undivided, operates unspent.”[64 - Kinetic Theories of Gravitation, Washington, 1877.]

With reference to the habitability of other planets, Tennyson has beautifully said —

“Venus near her! smiling downwards at this earthlier earth of ours,
Closer on the sun, perhaps a world of never fading flowers.
Hesper, whom the poets call’d the Bringer home of all good things;
All good things may move in Hesper; perfect people, perfect kings.
Hesper – Venus – were we native to that splendour, or in Mars,
We should see the globe we groan in fairest of their evening stars.
Could we dream of war and carnage, craft and madness, lust and spite,
Roaring London, raving Paris, in that spot of peaceful light?
Might we not in glancing heavenward on a star so silver fair,
Yearn and clasp the hands, and murmur, ‘Would to God that we were there!’”

The ancient Greek writer, Diogenes Laertius, states that Anaximander (610-547 B.C.) believed that the earth was a sphere. The Greek words are: μίσην τε τὴν γήν κεῖσθαι, κέντρυ τάξιν ἐπεχοῦσαν οὐσαν σφαιροειδῆ.[65 - The Observatory, June, 1894, p. 208.]

With reference to the Aurora Borealis, the exact nature of which is not accurately known, “a good story used to be told some years ago of a candidate who, undergoing the torture of a vivâ voce examination, was unable to reply satisfactorily to any of the questions asked. ‘Come, sir,’ said the examiner, with the air of a man asking the simplest question, ‘explain to me the cause of the aurora borealis.’ ‘Sir,’ said the unhappy aspirant for physical honours, ‘I could have explained it perfectly yesterday, but nervousness has, I think, made me lose my memory.’ ‘This is very unfortunate,’ said the examiner; ‘you are the only man who could have explained this mystery, and you have forgotten it.’”[66 - Nature, June 8, 1899.] This was written in the year 1899, and probably the phenomenon of the aurora remains nearly as great a mystery to-day. In 1839, MM. Bravais and Lottin made observations on the aurora in Norway in about N. latitude 70°. Bravais found the height to be between 62 and 93 miles above the earth’s surface.

The cause of the so-called Glacial Epoch in the earth’s history has been much discussed. The Russian physicist, Rogovsky, has advanced the following theory —

“If we suppose that the temperature of the sun at the present time is still increasing, or at least has been increasing until now, the glacial epoch can be easily accounted for. Formerly the earth had a high temperature of its own, but received a lesser quantity of heat from the sun than now; on cooling gradually, the earth’s surface attained such a temperature as caused a great part of the surface of the northern and southern hemispheres to be covered with ice; but the sun’s radiation increasing, the glaciers melted, and the climatic conditions became as they are now. In a word, the temperature of the earth’s surface is a function of two quantities: one decreasing (the earth’s own heat), and the other increasing (the sun’s radiation), and consequently there may be a minimum, and this minimum was the glacial epoch, which, as shown by recent investigations, those of Luigi de Marchi (Report of G. Schiaparelli, Meteorolog. Zeitschr., 30, 130-136, 1895), are not local, but general for the whole earth” (see also M. Neumahr, Erdegeschicht).[67 - Astrophysical Journal, vol. 14 (1901), p. 238, footnote.]

Prof. Percival Lowell thinks that the life of geological palæozoic times was supported by the earth’s internal heat, which maintained the ocean at a comparatively warm temperature.[68 - Mars as the Abode of Life, p. 52.]

The following passage in the Book of the Maccabees may possibly refer to an aurora —

“Now about this time Antiochus made his second inroad into Egypt. And it so befell that throughout all the city, for the space of almost forty days, there appeared in the midst of the sky horsemen in swift motion, wearing robes inwrought with gold and carrying spears, equipped in troops for battle; and drawing of swords; and on the other side squadrons of horse in array; and encounters and pursuits of both armies; and shaking of shields, and multitudes of lances, and casting of darts, and flashing of golden trappings, and girding on of all sorts of armour. Wherefore all men besought that the vision might have been given for food.”[69 - Second Book of the Maccabees v. 1-4 (Revised Edition).]

According to Laplace “the decrease of the mean heat of the earth during a period of 2000 years has not, taking the extremist limits, diminished as much as 1⁄300th of a degree Fahrenheit.”[70 - Humboldt’s Cosmos, vol. i. p. 169 (Otté’s translation).]

From his researches on the cause of the Precession of the Equinoxes, Laplace concluded that “the motion of the earth’s axis is the same as if the whole sea formed a solid mass adhering to its surface.”[71 - Quoted by Grant in History of Physical Astronomy, p. 71.]

Laplace found that the major (or longer) axis of the earth’s orbit coincided with the line of Equinoxes in the year 4107 B.C. The earth’s perigee then coincided with the autumnal equinox. The epoch at which the major axis was perpendicular to the line of equinoxes fell in the year 1250 A.D.[72 - Ibid., pp. 100, 101.]

Leverrier has found the minimum eccentricity of the earth’s orbit round the sun to be 0·0047; so that the orbit will never become absolutely circular, as some have imagined.

Laplace says —

“Astronomy considered in its entirety is the finest monument of the human mind, the noblest essay of its intelligence. Seduced by the illusions of the senses and of self-pride, for a long time man considered himself as the centre of the movement of the stars; his vain-glory has been punished by the terrors which his own ideas have inspired. At last the efforts of several centuries brushed aside the veil which concealed the system of the world. We discover ourselves upon a planet, itself almost imperceptible in the vast extent of the solar system, which in its turn is only an insensible point in the immensity of space. The sublime results to which this discovery has led should suffice to console us for our extreme littleness, and the rank which it assigns to the earth. Let us treasure with solicitude, let us add to as we may, this store of higher knowledge, the most exquisite treasure of thinking beings.”[73 - Exposition du Système du Monde, quoted by Carl Snyder in The World Machine, p. 226.]