Tail (astronomy)

“ Its course through the heavens combined singularly with the orbital place of the earth to favour curious inspection. The tail, when near its greatest development, lost next to nothing by the effects of perspective, and at the same time lay in a plane sufficiently inclined to the line of sight to enable it to display its exquisite curves to the greatest advantage. Even the weather was, on both sides of the Atlantic, propitious during the period of greatest interest, and the moon as little troublesome as possible. ”

“ VI.—The tail, then, is not a special matter which is transported in space with the comet, but a disturbance in the solar waves, just as sound is an atmospheric disturbance which is propagated with the velocity of the sonorous wave, although the air is not transported. The tail which we see in one position, then, is not that which we see in another; it is constantly renewed. ”

“ An inner portion of the tail, brighter than the rest, is more strongly curved, as if by solar repulsion. Stars are seen through the brighter parts of the tail, as they may be seen even through the coma and nucleus, with little diminution of their light. ”

“ In some cases we find the nucleus absent; in other cases we find the tail to be wanting. The tail is, no doubt, a conspicuous feature in those great comets which receive universal attention; but in the small telescopic objects, of which a few are generally found every year, this feature is usually absent. Not only do comets present great varieties in appearance, but even the aspect of a single object undergoes great change. The comet will sometimes increase enormously in bulk; sometimes it will diminish; sometimes it will have a large tail, or sometimes no tail at all. ”

“ Nov. 4 and 6, the tail did not appear; Nov. 11, the tail just begun to shew itself, but did not appear above 1⁄2 deg. long through a 10 feet telescope; Nov. 17, the tail was seen by Ponthæus more than 15° long ”

“ The magnificent luminous appendages or tails which many of is proudly display, are sometimes straight, and sometimes curved like a scimitar. With some of us this vapoury train of light attains an immense apparent length. Thus, for instance, my brother comet of 1811—which, by-the-bye, when first seen, possessed no visible tail—speedily threw out a luminous appendage covering some 25 degrees of heaven, or some 130,000,000 of miles. My own tail stretches some 11 degrees beyond this; that of my brother of 371 B.C., Aristotle tells you, occupied some 60 degrees of the heavens ”

“ The tail, indeed, is the most striking feature of the bird, being not only so very long, but seemingly endowed with the gift of perpetual motion, since it is never still, but bobs up and down, and sidewise, too, into every possible angle, and almost incessantly. ”

“ When catching the ephemeridæ that play above the water, the tail is not expanded: it is reserved for times of courtship. I have seen the female sitting quietly on a branch, and two males displaying their charms in front of her. One would shoot up like a rocket, than suddenly expanding the snow-white tail like an inverted parachute, slowly descend in front of her, turning round gradually to show off both back and front. ”

“ The rapidity with which light travels would of course make this explanation absolutely perfect in explaining cometic tails lying always exactly in a straight line directed from the sun, or with their axis so situated. But unfortunately this exceedingly rapid formation of the tail (a tail of ninety million miles in length would be formed in about eight minutes) is more than observation requires or can explain. Prof. Tyndall made a slight oversight in dealing with this part of his theory. ”

“ When the bird desires to direct its course to the right or left it strikes strongly with the opposite wing, which impels it to the proper side. The tail plays a prominent part in the movements of the bird, acting like the rudder of a ship, except that it moves upwards and downwards instead of sideways; if the bird wishes to rise, it raises its tail; it depresses it when it desires to descend; if it wishes to preserve a horizontal position it keeps its tail steady. ”

“ The rays of the sun in passing through or near the nucleus are so modified as to become visible in their further progress through the cometic atmosphere, while all the rest remain invisible. What we call the tail is merely a radius of the cometic atmosphere made visible, and as the comet moves through space, only different portions of the atmosphere come in sight, in obedience to the ordinary laws of light. There is no difficulty in accounting for the rise and fall of the tail at perihelion, nor for the tail preceding the nucleus afterward. ”

“ Because the centre of gravity of their bodies is always below the insertion of their wings, to prevent them falling on their backs, but near that point on which the body is, during flight, as it were, suspended. The positions assumed by the head and feet are frequently calculated to accomplish these ends, and give to the wings every assistance in continuing the progressive motion. The tail also is of great use, in regulating the rise and fall of birds, and even their lateral movements.—Fleming. ”

“ But, to obviate an objection that may be made from the appearing of no tail in such comets as shine but with a faint light, as if the secondary rays were then too weak to affect the eyes, and for that reason it is that the tails of the fixed stars do not appear, we are to consider, that by the means of telescopes the light of the fixed stars may be augmented above an hundred fold, and yet no tails are seen; that the light of the planets is yet more copious without any tail ”

“ Sometimes it may be a stormy petrel, flying like a swallow, skimming through the air in a hundred different directions, and seeming to play in that element; sometimes a ring-tail, which, with its piercing cry like that of a hawk, appears a messenger from the sun to bid the bold navigator welcome to the tropics, hovers for a few minutes over the ship, and then flies off with a jerk and disappears. ”

“ The soft, delicate, feathery-like form which the comet with its tail presents to the eye is wanting in a photograph, which shows principally a round head with an irregularly formed tail much like the knotted stalk of a plant. It follows that the light emitted by the central axis of the tail greatly exceeds in actinic power the diffuse light around it. ”

“ The cross-section of the tail, a little way behind the nucleus, was, in the present case at least, 100,000 miles in diameter: now, merely taking away the luminous matter from a tunnel 6,000 or 8,000 miles in diameter along the axis of the tail, could make but little difference with the amount of light received by the eye at a distance. If there were no tunnel, we should get from the central line of the tail the brightness corresponding to a thickness of 100,000 miles of luminous matter. Boring the tunnel would only reduce it to some 90,000 miles, and the difference would be hardly perceptible. ”

“ We remember that comets have sometimes more than one tail, and a theory has been advanced to account for this too. It is supposed that perhaps different elements are thrust away by the sun at different angles, and one tail may be due to one element and another to another. But if the comet goes on tail-making to a large extent every time it returns to the sun, what happens eventually? Do the tails fall back again into the head when out of reach of the sun's action? ”

“ The double envelope, so well defined in outline a few days previous, had disappeared, and there now remained only the bright nucleus bounded towards the tail by two arcs, one on either side of the centre, from which those rays seemed to spring which moved slightly in the direction of the sun, and then bent round to help in forming the tail. ”

“ Tails.--The tail of a comet is that part which flows from the head, and is afterwards repelled by the repulsive power of the sun into space. We shall deal with this repulsive power, whose existence we have already demonstrated, and the part which it plays in the formation of a comet's tail, in the next article. ”

“ One even raised itself high enough to secure a foothold. This animal's tail is also of use in another way. When caught, it will often remain motionless, but if touched, will either run a short distance with great speed, or quickly raising its tail and striking it forcibly against the surface on which it rests, and accompanying this with a quick motion of its hind-limbs, will jump from four to six inches, rising as high as two or three. ”

“ The tail is of service as a sculling-oar and a rudder, and its loud slapping of the water when an alarmed animal dives is an effective signal of danger to others. The head is thick and broad, the nose obtuse, the eyes small, the ears short and rounded. ”

“ The tail of a comet is oftentimes considered to be the comet itself, rather than a part of the same, but as the tail is the most distinctive feature of a comet, and is the part most visible to the naked eye, there has arisen the popular but mistaken idea of identity between the tail and the comet itself. ”

“ Multiple tails to comets are not exceptional, as was till lately believed; that quality has been found to be more general as comets have been observed with more powerful instruments. The recent comet (b, 1881) , it is true, seems to have but one tail; but that is because we are not far removed from the plane of its orbit, within which all the tails are included, so that they appear to us projected upon one another. For the same reason the tail of this comet appears straight. ”

“ In every case the tail would be formed outwards from A, at the rate at which light travels. This does not accord with the phenomena—in fact, the supposition that a tail could be formed at the rate at which light travels, will be found, on examination, to lead to many most manifest absurdities, which Professor Tyndall doubtless recognized when he sought escape from the supposition of such rapid tail formation, through the effects he attributed to the delayed appearance of the actinic cloud. ”

“ It is the longest tail we have ever seen in one number. If that tail was cut up into ordinary tails, such as common dogs wear, there would be enough for all the dogs in the Seventh ward, with enough left for a white wire clothes line. When he lays down his tail curls up like a coil of telephone wire, and if you take hold of it and wring you can hear the dog at the central office. If that dog is as long in proportion, when he gets his growth, and his tail grows as much as his body does, the dog will reach from here to the Soldier's home. ”

“ Four days passed, and it reappeared on the other side of the sun—having in the interval traversed nearly a semi-circle—in reality, of course, the perihelion end of its long oval path. At its reappearance, it had a tail still ninety millions of miles in length, but the tail with which it reappeared had, of course, a direction entirely different from that of the tail which had been seen before—the two directions were inclined about one hundred and sixty degrees to each other. ”

“ Now, from a cause already explained, the tail always tends to lay behind the comet, in the direction indicated by the lower tail in the diagram at 1, and, if produced, would pass to the left of the sun, as seen from the earth: the force of the radial stream, however, will not allow this lagging of the tail, and it is straightened out by this force ”

“ Red-tails, like other hawks, show a great variation in plumage. The dark phase of a Western Red-tail compares favorably with the plumage of an adult Golden Eagle, but the smaller size and the reddish upper tail surface which reflects the sun as the bird soars, furnishes the clue. ”

“ The tail, and the upper part of the body, have a singular power of being drawn out, or drawn in, like the tube of a telescope. There is sometimes a shell, or carapace, but often the body is covered only with a smooth firm skin, which, however, presents decided indications of being segmented. ”

“ It has a little red wafer on its nose and queer little patches of white under its tail, which it keeps on flicking as it goes in a comical automatic sort of way, in time with its steps, as if its tail were a kind of pedometer measuring off the distances it walks. ”

“ It has in particular shown not only the precise form of the tails, but the remarkable vicissitudes that they undergo. Professor Barnard’s photographs of Brooks’ comet in 1893 suggested, by the extraordinary changes in the form of the tail which they revealed, that the comet was encountering a series of obstructions in space which bent and twisted its tail into fantastic shapes. The reader will observe the strange form into which the tail was thrown on the night of October 21st. A cloud of meteors through which the comet was passing might have produced such deformations of its tail. ”

“ If in falling stars, as in comets, we distinguish between the head or nucleus and the tail, we shall find that the greater transparency of the atmosphere in tropical climates is evinced in the greater length and brilliancy of the tail which may be observed in those latitudes. The phenomenon is therefore not necessarily more frequent there, because it is oftener seen and continues longer visible. The influence exercised on shooting stars by the character of the atmosphere is shown occasionally even in our temperate zone, and at very small distances apart. ”

“ It is sufficient to point to the fact that no Bear is found in any Chaldean, Egyptian, Persian, or Indian Zodiacs, and that no bear was ever seen with such a tail! No one who had ever seen a bear would have called attention to a tail, such as no bear ever had, by placing in its very tip the most important, wondrous, and mysterious Polar Star, the central star of the heavens, round which all others revolve. ”