Meteor (Gr. lofty, in the air), any phenomenon of short duration occurring in the atmosphere. Rain, snow, hail, fog, and dew-are meteors distinguished as aqueous; the movements of the winds constitute the varieties of aerial meteors; luminous meteors are the singular phenomena displayed by the action of the aqueous particles diffused through the atmosphere upon the rays of light, such as fata Morgana, halo, mirage, rainbow, etc, and may also include the aurora borealis; and igneous meteors are such phenomena as lightning, aerolites, shooting stars, etc. Most of these are described in this work under tbeir own names. - In common language, the term meteor is applied only to those bodies which, as globes of tire or as shooting stars, are occasionally seen darting through the heavens at unknown distances from the earth, and in undetermined paths. Sometimes exploding and projecting upon the earth fragments of stone called meteoric iron, they are proved to be solid bodies in a state of intense heat, and are then known as aerolites or meteorolites. In ancient times these bodies were witnessed in different parts of the earth, and their appearance was chronicled as among the most wonderful natural exhibitions.
The Chinese records of such phenomena extend back to 644 B. C.; and from the 7th century B. C. to A. D. 333, 16 falls of aerolites are recorded in the astronomical annals of the Chinese. By the Greeks and Romans in the same period accounts are preserved of only four such falls. Humboldt says that it is remarkable that the Ionian school, in accordance with the present opinion, early assumed the cosmical origin of meteoric stones. Anaxagoras of ClazomensB held that the meteors are masses torn away from the earth by the violence of the rotation; and that between the earth and the moon there revolve other dark bodies, which can produce eclipses of the moon. Diogenes of Apollonia, as recorded by Stobaeus, also taught that dark masses of stone move with the visible stars and remain unseen by us. Plutarch in the life of Lysander (cap. xii.) expressly declares that falling stars "are really heavenly bodies, which from some relaxation of the rapidity of their motion, or by some irregular concussion, are loosened and fall, not so much upon the habitable part of the globe as into the ocean, which is the reason that their substance is seldom seen." The nature and movements of the meteoric bodies which fall upon the earth have already been considered under Aerolite. But some of the most extraordinary meteoric displays, of the nature of tire balls or bolides, and' of shooting stars, unaccompanied by falls of stone, may properly be noticed in this place.
The bolis is the tiery body from which aerolites are precipitated upon the earth; but many such bodies pass across the heavens, and sometimes explode and disappear, leaving behind no vestiges of their solid materials. They appear singly at irregular periods, and move with great rapidity across the sky. exhibiting sometimes a dazzling brilliancy, greater than that of the sun at noonday, as is remarked by Humboldt of one seen at Popayan in 1788. A luminous train follows them, and their path has been known to remain brilliant for several minutes after they have disappeared. Admiral Krusenstern, indeed, in his "Voyage," describes a fire ball the train of which shone for an hour after the body had disappeared, scarcely moving during this'time. They send forth vivid scintillations and present various bright colors, and the same meteor is differently described as seen from different places. Often they divide into two or more bodies which move along together, and sometimes they explode with a report like heavy thunder. They are of various apparent sizes, occasionally exceeding that of the moon. On Feb. 6, 1818, one was seen in England about 2 P. M. descending vertically and shining with a light equal to that of the sun.
Dr. E. D. Clarke, who described this in the "Annals of Philosophy," vol. xi., p. 273, was of opinion that meteorolites fell from this body; and in Lincolnshire it was reported that a hissing noise accompanied it, and a trembling of the earth was felt like the shock of an earthquake. The records of fire balls seen in the evening are very numerous. They appear at no particular season, and are limited to no particular portions of the earth, though most of the observations have been recorded in Europe. In 1623 one was seen over Germany, and described by Kepler. In 1676 one passed over Italy from the direction of Dalmatia about two hours after sunset, and disappeared toward Corsica. At Leghorn it was heard to explode, and fragments from it fell into the sea. Its height was estimated by Montanari at 38 m. Ilalley describes in the "Philosophical Transactions." No. 360, a meteor of extraordinary brilliancy which appeared over England in 1719 about 8 1/4 P. M. It suddenly illuminated the streets of London, causing the stars to disappear, and the moon, which before was shining brightly, to be hardly visible. The eye directed toward it could scarcely bear its brilliancy.
It moved like a falling star at a height estimated at 60 to 70 m., and with a velocity of 300 to 350 m. in a minute; through Devon and Cornwall and on the opposite coast of Brittany a loud explosion was heard proceeding from it. On Aug. is, 1783, at 9 P. M., another very remarkable meteor of this character was seen over a large part of Europe from the north of Ireland to Rome. It crossed the zenith at Edinburgh, appearing single and well defined, of a greenish shade, and with a tail; but at Greenwich it had the appearance of two bright balls with other luminous bodies following it. Its height was estimated to be above the limits of the atmosphere, its speed more than 1,000 m. a minute, and its diameter more than a mile. Cavallo describes its bursting and the noise of the explosion, which was 10 minutes in reaching the earth. Bowrditch describes, in the "Memoirs of the American Academy," a meteor seen Nov. 21, 1819, at Dan vers, Mass., and in Baltimore, Md., the diameter of which appeared to he half a mile. Its direction was S. 44° W., and its height, at first 38 m., was soon reduced to 22 m. Two minutes after its disappearance a rumbling noise was heard which lasted longer than a minute.
On the evening of July 20, 1860, about a quarter before 10 o'clock, a meteor passed over the state of New York, from the west, being seen on Lake Erie, and soon afterward at Buffalo, Albany, New York city, Newr Haven, Newport, R. I., and New Bedford, Mass. At the south it was visible in the state of Delaware. By many observers it was at first supposed to be a display of rockets or of Roman candles; and all had the impression that its elevation was only a few hundred feet. From a vessel off Sandy Hook it appeared to fall into the sea at a short distance. First appearing as a single body, it was observed to separate into two balls, which kept along together, emitting sparks and what appeared to be flames. A table of meteors and meteoric showers given in Izarn's Lithologie astrono-mique includes one of iron in Lucania, 54 B. C.; one of mercury (!) in Italy, of unknown date; a fall of about 1,200 stones, one of which weighed 160 lbs. and another 60, at Padua in 1510; sulphurous rains at Copenhagen in 1646 and in the county of Mansfeld in 1658, and a shower of sulphur at Brunswick in October, 1721; a shower of fire at Quesnoy, Jan. 4, 1717; one of sand lasting 15 hours in the Atlantic, April 6, 1719; and extensive showers of stones at Aden, July 24, 1790, and in France, May 15, 1864. (See Aerolite.) - Falling stars resembling small bolides are often seen on a clear night shooting at the rate of four or five an hour across the sky.
These are termed "sporadic" meteors, in contradistinction to the "periodic," which at certain periods appear often in vast numous like showers of fire. Displavs of this kind are recorded as occurring in October, 902; Oct. 19, 1202; and Oct. 21, 1366 (O. S.). Each time the stars are said to have been in motion all night, falling like locusts, and in numbers which no one could count. More modern occurrences of this phenomenon were observed on the night of Nov. 9-10, 1787, in southern Germany; and after midnight of Nov. 12-13, 1799, as described by Humboldt and Bonpland, in Cuniana. The same phenomenon was also observed as far south as the equator, and over North America, even to Labrador and Greenland, and on the other side of the Atlantic in Germany. From the bearing and course of the meteors at different points, their elevation Avas computed to be 1,419 m. In 1818 meteoric displays of great brilliancy were seen on the same night of Nov. 12-13, in England, and again in 1822 at Potsdam in Brandenburg. In some of the exhibitions about this period a deposit of dust was observed upon the surface of the water, on the buildings, and other objects.
On the same night in 1831 and in 1832, the same phenomenon reappeared in Europe and America. But the year 1833 is memorable for the most magnificent display on record. This was on the same night of November also, and was visible over all the United States, and over a part of Mexico and the West India islands. Together with the smaller shooting stars, which fell like snow flakes and produced phosphorescent Hues along their course, there were intermingled large fire balls, which darted forth at intervals, describing in a few seconds an arc of 30° or 40°. These left behind luminous trains, which remained in view several minutes, and sometimes half an hour or more. One of them seen in North Carolina appeared of larger size and greater brilliancy than the moon. Some of the luminous bodies were of irregular form, and remained stationary for a considerable time, emitting streams of light. At Niagara the exhibition was especially brilliant, and probably no spectacle so terribly grand and sublime was ever before beheld by man as that of the firmament descending in fiery torrents over the dark and roaring cataract.
It was observed that the lines of all the meteors if traced back converged in one quarter of the heavens, which was y Leonis Majoris; and this point accompanied the stars in their apparent motion westward, instead of moving with the earth toward the east. The source whence the meteors came was thus shown to be independent of the earth's rotation and exterior to our atmosphere. As computed by Prof. Deni-son Olmsted of New Haven, it could not have been less than 2,238 m. from the earth. Three successive annual returns of this phenomenon on the same night led astronomers on both sides of the Atlantic in the following years to watch for its recurrence; and displays more or less brilliant, but not by any means equal to that of 1833, were witnessed in dilferent places in Europe or America every year till and including 1839. They were again observed on the night of Nov. 12-13, 1841 and 1846, and again in 1866 and every following year till 1871 inclusive. But it is not alone in November that periodic exhibitions of the fall of meteors have been observed.
It is found that they often occur about the 10th or from the 9th to the 14th of August; and Humboldt named other periods that are likely to prove of the same interest, as about the 22d to the 25th of April, between the 6th and 12th of December, the 27th and 29th of November, and about the 17th of July. He noticed the singular coincidence which different observers have remarked in the great brilliancy of the aurora borealis during the fall of the meteors. Prof. Olmsted early suggested that the meteors probably emanate from a nebulous body, which revolves around the sun in an elliptical orbit, the aphelion of which meets the orbit of the earth at the times of the annual exhibitions. The nebular character is inferred from the fact that none of the meteors, though they fall toward the earth with prodigious velocity, ever reach it in a solid state, all being dissipated in the atmosphere, and no material substance found to indicate their nature. Arago adopted a view similar to that of Olmsted. He suggests that the meteoric bodies may constitute a stream in the form of an annular zone, within which they pursue one common orbit; that there are several such streams, which intersect, each at its own period, the earth's orbit; and that through each the myriads of small cosmical bodies are irregularly dispersed.
But the demonstration of the real orbits pursued by these bodies (at least in the case of the more remarkable periodical showers) belongs to the years following the display of Nov. 13-14, 1866. Prof. Newton of Yale"college had predicted the recurrence of a great display of November meteors, such as had been seen in the years 1799 and 1833, for the year 1866; and he even announced as the probable hour of the display early morning in America. He was within a few hours of the truth, the display occurring during the early morning in Europe, and closing before morning began in America. European astronomers noted the point in the heavens whence the meteors seemed to radiate, not far from the star y Leonis, as in 1833. Then followed an inquiry into the orbit of the meteors. Prof. Newton had indicated five orbits as capable of explaining the recurrence of great displays about thrice in a century. Of these the three most probable were: first, a year and 1/33 part; secondly, a year less 1/33 part; and thirdly, 33 1/3, years. Prof. Newton considered the last named period improbable, because it implied an orbit extending beyond the orbit of the distant plan-et Uranus. He therefore regarded a period of rather more or rather less than a year as probably the true period of these meteors.
But just at this time a remarkable discovery was made by Schiaparelli of Italy. Noticing that the comet II., 1862, passed the earth's orbit nearly at the place she occupies on Aug. 10-11, he was led to inquire whether the path followed by the comet resembled that traversed by the August meteors, assuming that they have the same period of revolution as the comet (about 124 years). He found the agreement so close as to leave no doubt of the existence of a real association between the August meteors and the large comet of 1862. This will be seen from the following comparison:
Comet of 1862.
Longitude of ascending node.. .
Astronomers therefore began to regard as not improbable the theory that the true period of the November meteors is about 33 1/3 years.
Peters, Temple. Leverrier, and other astronomers calculated the path on this assumption, and then they inquired whether any known comet possesses a similar path. By a singular coincidence, a telescopic comet had been found that very year, 1866, which traversed an orbit so near to that obtained for the meteors as to leave no doubt of the identity of the two orbits. The comparison is as follows:
Longitude of descending node..
But the matter was removed from the region of mere probability by the researches of Prof. Adams, the well known English astronomer. Analyzing the pertnrbative effects of the planets upon the members of the November meteor system, on the various assumptions pointed out by Prof. Newton as mentioned above, he found that the actual changes taking place in the position of the meteors' node (changes indicated by the gradual alteration of the date of the shower) imply an orbit extending so as to bring the meteors under the disturbing influence of the giant planets. Hence the recurrence of great displays thrice in a century can only be explained by the last assumption of Newton, assigning to the meteors a period of 33 1/3 years or thereabouts. Adams selected a period of 33 1/4 years, and found the nodal changes satisfactorily accounted for. Since then the identity of another system, the meteors of Nov. 27 - 29, so far as their path is concerned, with the short-period comet called Bie-la's, has been satisfactorily demonstrated, by the occurrence of a shower (predicted on that assumption) on Nov. 27, 1872. More than 100 meteor systems are now recognized, not in all or in most cases by the periodic recurrence of great displays, but by the existence of distinct radiant points.
Even 10 or 12 meteors only, seen on the same night, can be safely assigned to a single system, when they are all found to radiate from nearly the same point of the star sphere. - There is every reason to believe that meteoric astronomy is as yet only in its infancy, and that the combined study of meteor systems and comets will throw great light on many most interesting subjects of astronomical research. Some of the researches of Prof. Kirkwood into the relations presented by com-seem very promising in this respect.