Halley's Comet

“ The most ominous of all prophesies connected with the coming of Halley’s Comet this year was made by the venerable General Ballington Booth, the head of the Salvation Army. Speaking in London, immediately after Halley’s Comet had been located, early this year, General Booth said:
“We are, this year, rapidly approaching the end of all things, with similar results, but far surpassing in horrors any disaster that has gone before. ”

“ Fig. 99.—Orbit of Halley's comet.
Coming to recent times, we have the great comets of 1843 and of 1858, the history of neither being known. Quite possibly they arrived then for the first time. Possibly the second will appear again in 3808. But besides these great comets, there are a multitude of telescopic ones, which do not show these striking features, and have no gigantic tail. Some have no tail at all, others have at best a few insignificant streamers, and others show a faint haze looking like a microscopic nebula. ”

“ But how much more wonderful does man become, when we find he has the power to foretell to us the return of comets that have never been seen by any one living now—comets that have been, during our lives, travelling into the far-off fields of space! Strange that a simple man can prophesy, to a day, their return! Many of us now living remember a beautifully bright and clear comet, which in 1835 appeared, as had been predicted, after an absence of seventy-six years. It was called Halley’s comet, after its first discoverer. ”

“ From the data we have been able to collect it would appear that when a comet comes to have a period of over 70 years, it is either too far removed from the sun at its aphelion passage, or its mass is too great for it to be perturbed by the attraction of any of the planets. For instance, we have Halley's comet, which has been observed for not far from 2000 years, whose period has averaged very close upon 77 years during the whole of that time, showing that it has not been perturbed to any appreciable extent when near its perihelion passage. ”

“ Possibly the second tail of the comet of 1724, which was directed towards the sun, may have been of this nature.
365The influence of the ethereal medium on the motions of Halley’s comet will be known after another revolution, and future astronomers will learn, by the accuracy of its returns, whether it has met with any unknown cause of disturbance in its distant journey. Undiscovered planets, beyond the visible boundary of our system, may change its path and the period of its revolution, and thus may indirectly reveal to us their existence, and even their physical nature and orbit. ”

“ Halley's comet, therefore, is an integral member of our solar system, as much so as the earth or Neptune, though it is utterly unlike them in appearance and constitution, and though its path is so utterly unlike theirs that it approaches the sun nearer than our earth, and recedes farther than Neptune. But there are other comets, which are [227] not permanent members of our system, but only passing visitors. From the unfathomed depths of space they come, to those depths they go. They obey the law of gravitation so far as our sight can follow them, but what happens to them beyond? ”

“ Halley's comet, with its inconveniently short period of about seventy-seven years, has repeatedly troubled the nations and been regarded as a sign sent from Heaven:
Ten million cubic miles of head,
Ten billion leagues of tail,
all provided for the sole purpose of warning one petty race of earth-folks against the evils likely to be brought against them by another. ”

“ It is not only cast away from the sun: it is really cast by the sun—shadow-like, although not of the nature of shadow. It only appears when the comet gets near to the sun's effulgence, and is lost altogether when that body gets far from the great source of mundane light and heat. It is raised from the comet's body, by the power of sunshine, as mist is from damp ground. When Halley's Comet of 1682 approached the fierce ordeal of its perihelion position, the exhalation of its tail was distinctly perceived. ”

“ That there never is a moment when there is not some comet in the sky. Virtually there is no year in which several new comets are not discovered, so plentiful are they. Luminous fleas on a vast black dog—in popular impressions, there is no realization of the extent to which this solar system is flea-bitten.
If a comet have not the orbit that astronomers have predicted—perturbed. If—like Halley's comet—it be late—even a year late—perturbed. When a train is an hour late, we have small opinion of the predictions of timetables. ”

“ People were terrified of comets in those days, and generally associated them with disaster: and it was only when Newton and Halley showed that comets obey regular laws that this fear was dissipated. It is seldom very difficult to find some disaster which could be
Halley's Comet on the Bayeux Tapestry. ”

“ So did Mithridates. So did one Toma, in Hungary, only this year.
King Louis “the Debonair” of France, died from fear of a Comet (Halley’s Comet) in 837 A. D.
Emperor Charles V., of Germany and Spain, the monarch who boasted that “the sun never set on his dominions,” was so moved by the appearance of a Comet in 1556, that he gave up his crown and became a monk.
Certain metaphysicians have held that there is a substance in a Comet, or in its tail, which has a weird effect on man’s brain, as moonshine is believed to have on some men, making them lunatics. ”

“ Already the outermost jets of flame had reached the Moon. From one instant to the next the flaming rays would descend upon the Earth.
All eyes were distended with horror when it was seen that the horizon was lighting up with tiny violet flames as from a vast fire.
An instant afterward, the Comet diminished in brilliancy. This was apparently because the Comet, upon touching the atmosphere of our [Pg 124] Earth, had come within the penumbra of our planet and had lost part of its reflected light coming from the Sun. But in reality this apparent extinction was the effect of contrast. ”

“ A new explanation has been proposed almost every time that a great discovery has been made in the theory of light, heat, chemistry, or electricity.
Halley’s comet remained the only one of which a prediction of the return had been confirmed, until the orbit of the small, ill-defined comet found by Pons in 1819 was computed by Encke, and found to have a period of 3 1/3 years. ”

“ A Comet may be regarded as a huge lighted torch whirling through space, which may be brought dangerously near that upper layer of highly inflammable hydrogen. If the gas shall ever be touched off by this flying torch, our planet will be ignited. The whole atmosphere will become a seething ocean of flame, in which forests and cities will burn like straw, in which oceans will boil away in vast clouds of steam, and in which all animal life will be snuffed out of existence before it shall realize that the world is on fire. ”

“ Although more than two centuries have passed since Halley was in his prime, the possibility of a collision with some vagabond star still haunts the mind of the astronomer.
That a collision is apt to occur is an admitted astronomic fact. The latest estimate, made in 1909 by Prof. William H. Pickering of Harvard University, would seem to prove that the core of one Comet in about 100,000,000 Comets will hit the earth squarely. An encounter with some part of a Comet’s head will happen once in 4,000,000 years. ”

“ Great comets are almost always unexpected visitors. There is only one great comet that we know has been seen more than once, and expect with reasonable certainty to see again. This is Halley's comet, which has been returning to a near approach to the sun at somewhat irregular intervals of seventy-five to seventy-eight years during the last centuries: indeed, it is possible that it was this comet that was coincident with the invasion of England by William the Conqueror. ”

“ Hence they must be matter of very small density; their tails can be nothing more dense than a filmy [Pg 342] mist, but their nucleus must be something more solid and substantial.
Fig. 100.—Various appearances of Halley's comet when last seen.
I have said that comets arrive from the depths of space, rush towards and round the sun, whizzing past the earth with a speed of twenty-six miles a second, on round the sun with a far greater velocity than that, and then rush off again. Now, all the time they are away from the sun they are invisible. ”

“ As Clairaut remarked, in publishing his calculations concerning the expected reappearance of Halley’s Comet, a body which passes into regions so remote, and which is hidden from our view during such long periods, might be exposed to the influence of forces totally unknown to us, such as the attraction of other comets, or of planets too far removed from the sun to be ever perceived by us. ”

“ The seed which was thus sown by Halley has borne fruit. In Halley’s own [Pg 114] time, learned men were brooding over the ultimate destruction of the Earth by collision with a Comet.
Dr. Whiston, who succeeded Newton at Cambridge in the Lucasian chair of mathematics, was sure that a Comet caused the Deluge, and went so far as to prophesy that a Comet, as it passed us on its outward course from the Sun, would ultimately bring about a “General Conflagration,” and thus envelope the Earth in flames. ”

“ The law of gravitation had therefore enabled men to recognise in Halley's Comet an addition to the number of the primary bodies in the solar system—the first addition that had been made since prehistoric times. On March 13, 1781, Sir WILLIAM HERSCHEL {38} detected a new object, which he at first supposed to be a comet, but afterwards recognised as a planet far beyond the orbit of Saturn. This planet, to which the name of Uranus was finally given, had a mean distance from the Sun nineteen times that of the Earth, and a diameter four times as great. ”

“ From that time forth this Comet, which returned in 1835, and is reappearing in this year (1910) , has been known as Halley’s Comet. [Pg 92]
EDMUND HALLEY.
[Pg 93] Besides this achievement, Halley accomplished many other noteworthy feats in astronomy, such as his discovery of the proper motions of the fixed stars; his detection of the “long inequality” of Jupiter and Saturn, and of the acceleration of the moon’s mean motion; his theory of variation, including the hypothesis of various magnetic poles, with his suggestion of the magnetic origin of the aurora borealis ”

“ Photography of comets has developed remarkably within recent years, especially under the deft manipulation of Barnard, whose plates, in particular during his residence at the Lick Observatory on Mount Hamilton, California, show the features of cometary heads and tails in excellent definition. Halley's comet, at the 1910 apparition, was particularly well photographed at many observatories.
The question is often asked, When will the next comet come? If a large bright comet is meant, astronomers cannot tell. At almost any time one may blaze into prominence within only a few days. ”

“ All the people then saw that their time had come. Many-thousand-throated cries rent the air. “The World is burning. We are on fire!” they cried.
All the horizon, in fact, was now lit up with flame, forming a crown of blue light. It was, indeed, as had been foreseen by scientists, the oxide of carbon igniting in the air and producing anhydrid of carbon. Clearly, too, hydrogen from the Comet combined with it. ”

“ The nuclei of many comets which seemed solid and brilliant to the naked eye have been resolved into mere vapour by telescopes of high powers; in Halley’s comet there was no solid part at all.
The nebulosity immediately round the nucleus is so diaphanous, that it gives little light; but at a small distance the nebulous matter becomes suddenly brilliant, so as to look like a bright ring round the body. Sometimes there are two or three of these luminous concentric rings separated by dark intervals, but they are generally incomplete on the part next the tail. ”

“ Halley supposed, therefore, that the orbit of this comet was, not a parabola, but a very elongated ellipse, and that it would return about the year 1758. The truth of his conjecture was fully confirmed in January, 1759, by Messier. The first person, however, who saw Halley’s comet, as it is now called, was George Palitzch, a farmer in the neighbourhood of Dresden, who had studied astronomy by himself, and fitted up a small observatory. ”

“ He has collected a formidable mass of photographic evidence which seems to show that there are other influences at work besides the Sun’s radiation, and that these influences manifest themselves in distorting and breaking a Comet’s tail. In some Comets of recent years, streams of matter have been shot out in large angles to the main direction of the tail without being at all bent by the pressure of light. In Morehouse’s Comet of 1908, tails were repeatedly formed and discarded to drift bodily out into space and melt away. ”

“ Each of the planets solicits the comet to depart from its track, and though the amount of these attractions may be insignificant in comparison with the supreme controlling force of the sun, yet the departure from the ellipse is quite sufficient to produce appreciable irregularities in the comet's movement. At the time when Halley lived, no means existed of calculating with precision the effect of the disturbance a comet might experience from the action of the different planets. ”