Solar eclipse

“ Every solar eclipse has therefore a definite "life" of its own upon the earth, lasting about 1150 years, or 64 saros returns, and working its way little by little across our globe from north to south, or from south to north, as the case may be. Let us take an imaginary example. A partial eclipse occurs, say, somewhere near the North Pole, the edge of the "partial" shadow just grazing the earth, and the "track of totality" being as yet cast into space. ”

“ A Moon eclipse is visible from anywhere on the terrestrial globe that is on the same side as the Moon, whereas a solar eclipse is only visible from a small part of the Earth since our planet is larger than the Moon, so that it can hide the sunlight from the whole surface. ”

“ If it is an eclipse of the Moon, it will be total from its 13th until its 36th recurrence. There will be then about 13 partial eclipses, each of which will be smaller than the last, when they will fail entirely, the conjunction taking place [27] so far from the node that the Moon does not touch the Earth’s shadow. The whole interval of time over which a series of lunar eclipses thus extend will be about 48 periods, or 865 years. When a series of solar eclipses begins, the penumbra of the first will just graze the earth not far from one of the poles. ”

“ The spectroscope and the camera are steadily ousting the simple telescope of every sort and unassisted eye observations from solar eclipse work.
Mrs. Todd has the following apt remarks by way of summary of the results to an individual of observing a total eclipse of the Sun:—“I doubt if the effect of witnessing a total eclipse ever quite passes away. The impression is singularly vivid and quieting for days, and can never be wholly lost. A startling nearness to the gigantic forces of Nature and their inconceivable operation seems to have been established. ”

“ Especially useful has photography proved itself in the observation of total solar eclipses. It is only when the sun's bright disk is completely obscured by the interposed moon that we can see the faintly luminous structure of the solar corona, that great appendage of our sun, whose exact nature is still unexplained. Only during the few minutes of total eclipse in each century can we look upon it; and keen is the interest of astronomers when those few minutes occur. But it is found that eye observations made in hurried excitement have comparatively little value. ”

“ In a total solar eclipse, the time which elapses from the moment when the moon's disc first begins to impinge upon that of the sun at his western edge until the eclipse becomes total, lasts about an hour. ”

“ The corona has been carefully studied at every solar eclipse during the last 30 years, both with the spectroscope and with the telescope, supplemented by photography, and a number of ingenious theories of its constitution have been propounded; but our present knowledge of its nature hardly goes beyond Professor Young’s description of it as “an inconceivably attenuated cloud of gas, fog, and dust, surrounding the sun, formed and shaped by solar forces.” ”

“ And in some measure through their own fault, for many partial hints and some distinct statements from earlier observers had given unheeded notice that some such phenomenon might be expected to attend a solar eclipse.
What we now call the "chromosphere" is an envelope of glowing gases, by which the sun is completely covered, and from which the "prominences" are emanations, eruptive or flame-like. Now, continual indications of the presence of this fire-ocean had been detected during eclipses in the eighteenth and nineteenth centuries. ”

“ When totality is over and the corona has faded away, the moon's disc creeps little by little from the face of the sun, light and heat returns once more to the earth, and nature recovers gradually from the gloom in which she has been plunged. About an hour after totality, the last remnant of moon draws away from the solar disc, and the eclipse is entirely at an end.
The corona, the chromosphere, and the prominences are the most important of these accompaniments of the sun which a total eclipse reveals to us. ”

“ In an elaborate memoir [4] he showed that the ancient solar eclipses described by Herodotus, Thucydides, and others, which seemed to require an increased value of the secular acceleration of the moon's mean motion to bring them into line with modern results, might safely be neglected, the ambiguity of the accounts in each case rendering uncertain either the totality of the eclipse or the place from which it was visible. ”

“ It is very generally noticed that great changes take place in the meteorological conditions of the atmosphere as an eclipse of the Sun runs its course from partial phase to totality, and back again to partial phase. It goes without saying that the obstruction of the solar rays by the oncoming Moon would necessarily lead to a steady and considerable diminution in the general temperature of the air. ”

“ If we add to this that at midnight the whole of the sky, except a round spot some four or five times the diameter of the moon, would be occupied by this cis-lunar matter under direct solar illumination, instead of that illumination from behind which such matter would receive during total eclipse, we see that the darkness of our midnight sky speaks as decisively against this theory as does the brightness of the long rays seen during total eclipse. ”

“ In a distant future, we no longer can be witnesses of total solar eclipses since the Moon, even in its closest-to-the-Earth position, it won’t be able to block the Sun completely, and there will be only annular or partial eclipses. ”

“ Use of eclipses.—At all times and among all peoples eclipses, and particularly total eclipses of the sun, have been reckoned among the most impressive phenomena of Nature. In early times and among uncultivated people they were usually regarded with apprehension, often amounting to a terror and frenzy, which civilized travelers have not scrupled to use for their own purposes with the aid of the eclipse predictions contained in their almanacs, threatening at the proper time to destroy the sun or moon, and pointing to the advancing eclipse as proof that their threats were not vain. ”

“ Olympic Gods turned mid-day into night hiding the light of the dazzling sun; an overwhelming dread fell upon men.” The poet’s language may evidently apply to a total eclipse of the Sun; and investigations by Oppolzer and Millosevich make it probable that the reference is to the total eclipse of the Sun which happened on April 6, 648 B.C. This was total at about 10 a.m. ”

“ In awaiting the darkness which is expected to manifest itself an unthinking and inexperienced observer is apt to look out for the coming obscurity, as he looks out for night-fall half an hour or more after sunset and during the evening twilight. The darkness of an eclipse is all this and something more. It is something more in two senses; for the interval of time between the commencement of an eclipse and totality is different in duration and different in quality, so to speak, from the diminution of daylight on the [42] Earth which ensues as the twilight of evening runs its course. ”

“ The primary meaning of the word “Eclipse” (ἔκλειψις) is a forsaking, quitting, or disappearance. Hence the covering over of something by something else, or the immersion of something in something; and these apparently crude definitions will be found on investigation to represent precisely the facts of the case.
Inasmuch as the Earth and the Moon are for our present purpose practically “solid bodies,” each must cast a shadow into space as the result of being illuminated by the Sun, regarded as a source of light. ”

“ The thrilling descriptions of the effects of the oncoming darkness of totality, derived from the records of past total eclipses, are not likely to be improved upon in the future, for we shall receive them more and more from amateurs and less and less from astronomical experts. Every additional total eclipse which happens testifies to the fact that the time and thoughts of these latter classes [56] of people will be to an increasing degree dedicated to instrumental work rather than to simple naked eye or even telescopic observation. ”

“ The truth is, that far from being developed by misty air, it is peculiarly liable to be effaced by it. The purer the sky, the more extensive, brilliant, and intricate in the details of its structure the corona appears. Take as an example General Myer's description of the eclipse of 1869, as seen from the summit of White Top Mountain, Virginia, at an elevation above the sea of 5,523 feet, in an atmosphere of peculiar clearness. ”

“ The darkness, which had been gradually creeping in with the progress of the eclipse, is then at its maximum. Although subject to great variations in different eclipses, the darkness is never so great as might be expected from the complete obscuration of our luminary, as the part of our atmosphere which is still exposed to the direct rays of the Sun, reflects to us some of that light, which thus diminishes the darkness resulting from the disappearance of the Sun. ”