SHOOTING-STARS.--METEORS OF NOVEMBER 14.
Although shooting-stars have doubtless been observed in all ages of the
world, it is only within the last half century that they have attracted
the special attention of scientific men. A few efforts had been made to
determine the height of such meteors, but the first general interest in
the subject was excited by the brilliant meteoric display of November
13, 1833. This shower of fire can never be forgotten by those who
witnessed it. The meteors were observed from the West Indies to British
America, and from 60° to 100° west longitude from Greenwich. As early as
10 o'clock on the evening of the 12th shooting-stars were observed with
unusual frequency; their motions being generally westward. Soon after
midnight their numbers became so extraordinary as to attract the
attention of all who happened to be in the open air. The meteors,
however, became more and more numerous till 4, or half past 4, o'clock;
and the fall did not entirely cease till ten minutes before sunrise.
From 2 to 6 o'clock the numbers were so great as to defy all efforts at
counting them; while their brilliancy was such that persons sleeping in
rooms with uncurtained windows were aroused by their light. The meteors
varied in apparent magnitude from the smallest visible points to
fire-balls equaling the moon in diameter. Occasionally one of the larger
class would separate into several parts, and in some instances a
luminous train remained visible for three or four minutes. No sound
whatever accompanied the display. It was noticed by many observers that
all the meteors diverged from a point near the star _Gamma Leonis_; in
other words, their paths if traced backward would intersect each other
at a particular locality in the constellation Leo. In some parts of the
country the inhabitants were completely terror-stricken by the
magnificence of the display. In the afternoon of the day on which the
shower occurred the writer met with an illiterate farmer who, after
describing the phenomena as witnessed by himself, remarked that "the
stars continued to fall till none were left," and added, "I am anxious
to see how the heavens will appear this evening; I believe we shall see
no more stars." A gentleman of South Carolina described the effect on
the negroes of his plantation as follows:--"I was suddenly awakened by
the most distressing cries that ever fell on my ears. Shrieks of horror
and cries for mercy I could hear from most of the negroes of the three
plantations, amounting in all to about 600 or 800. While earnestly
listening for the cause I heard a faint voice near the door, calling my
name. I arose, and, taking my sword, stood at the door. At this moment I
heard the same voice still beseeching me to arise, and saying, 'O my
God, the world is on fire!' I then opened the door, and it is difficult
to say which excited me the most,--the awfulness of the scene, or the
distressed cries of the negroes. Upwards of a hundred lay prostrate on
the ground,--some speechless, and some with the bitterest cries, but
with their hands raised, imploring God to save the world and them. The
scene was truly awful; for never did rain fall much thicker than the
meteors fell towards the earth; east, west, north, and south, it was the
same."
At the time of this wonderful meteoric display Captain Hammond, of the
ship _Restitution_, had just arrived at Salem, Massachusetts, where he
observed the phenomenon from midnight till daylight. He recollected with
astonishment that precisely one year before, viz., on the 13th of
November, 1832, he had observed a similar appearance (although the
meteors were less numerous) at Mocha, in Arabia. It was found, moreover,
as a further and most remarkable coincidence, that an extraordinary fall
of meteors had been witnessed on the 12th of November, 1799. This was
seen and described by Andrew Ellicott, Esq., who was then at sea near
Cape Florida. It was also observed by Humboldt and Bonpland, in Cumana,
South America. Baron Humboldt's description of the shower is as
follows:--"From half after two, the most extraordinary luminous meteors
were seen toward the east. Thousands of bolides and falling stars
succeeded each other during four hours. They filled a space in the sky
extending from the true east 30° toward the north and south. In an
amplitude of 60° the meteors were seen to rise above the horizon at
E.N.E. and at E., describe arcs more or less extended, and fall toward
the south, after having followed the direction of the meridian. Some of
them attained a height of 40°, and all exceeded 25° or 30°. Mr. Bonpland
relates, that from the beginning of the phenomenon there was not a space
in the firmament equal in extent to three diameters of the moon, that
was not filled at every instant with bolides and falling stars. The
Guaiqueries in the Indian suburb came out and asserted that the firework
had begun at one o'clock. The phenomenon ceased by degrees after four
o'clock, and the bolides and falling stars became less frequent; but we
still distinguished some toward the northeast a quarter of an hour after
sunrise."
This wonderful correspondence of dates excited a very lively interest
throughout the scientific world. It was inferred that a recurrence of
the phenomenon might be expected, and accordingly arrangements were made
for systematic observations on the 12th, 13th, and 14th of November. The
periodicity of the shower was thus, in a very short time, placed wholly
beyond question. The facts in regard to the phenomena of November 13,
1833, were collected and discussed by Olmsted, Twining, and other
astronomers. The inquiry, however, very naturally arose whether any
trace of the same meteoric group could be found in ancient times. To
determine this question many old historical records were ransacked by
the indefatigable scientist, Edward C. Herrick, in our own country, and
by Arago, Quetelet, and others, in Europe. These examinations led to the
discovery of ten undoubted returns of the November shower previous to
that of 1799. The descriptions of these former meteoric falls are given
by Professor H. A. Newton in the _American Journal of Science_, for May,
1864. They occurred in the years 902, 931, 934, 1002, 1101, 1202, 1366,
1533, 1602, and 1698. Historians represent the meteors of A.D. 902 as
innumerable, and as moving like rain in all directions. The exhibition
of 1202 was scarcely less magnificent. "On the last day of Muharrem,"
says a writer of that period, "stars shot hither and thither in the
heavens, eastward and westward, and flew against one another like a
scattering swarm of locusts, to the right and left; this phenomenon
lasted until daybreak; people were thrown into consternation, and cried
to God the Most High with confused clamor." The shower of 1366 is thus
described in a Portuguese chronicle, quoted by Humboldt: "In the year
1366, twenty-two days of the month of October being past, three months
before the death of the king, Don Pedro (of Portugal), there was in the
heavens a movement of stars such as men never before saw or heard of. At
midnight, and for some time after, all the stars moved from the east to
the west; and after being collected together, they began to move, some
in one direction and others in another. And afterward they fell from the
sky in such numbers, and so thickly together, that as they descended low
in the air they seemed large and fiery, and the sky and the air seemed
to be in flames, and even the earth appeared as if ready to take fire.
That portion of the sky where there were no stars seemed to be divided
into many parts, and this lasted for a long time."
The Showers of 1866-9.
The fact that all great displays of the November meteors have taken
place at intervals of 33 or 34 years, or some multiple of that period,
had led to a general expectation of a brilliant shower in 1866. In this
country, however, the public curiosity was much disappointed.[22] The
numbers seen were greater than on ordinary nights, but not such as would
have attracted any special attention. The greatest number recorded at
any one station was seen at New Haven by Professor Newton. On the night
of the 12th 694 were counted in five hours and twenty minutes, and on
the following night, 881 in five hours. A more brilliant display was,
however, witnessed in Europe. Meteors began to appear in unusual
frequency about 11 o'clock on the night of the 13th, and their numbers
continued to increase with great rapidity for more than two hours; the
maximum being reached a little after 1 o'clock. A writer in Edinburgh,
Scotland, thus describes the phenomenon as observed at that
city:--"Standing on the Calton Hill, and looking westward,--with the
observatory shutting out the lights of Princes Street,--it was easy for
the eye to delude the imagination into fancying some distant enemy
bombarding Edinburgh Castle from long range; and the occasional
cessation of the shower for a few seconds, only to break out again with
more numerous and more brilliant drops of fire, served to countenance
this fancy. Again, turning eastward, it was possible now and then to
catch broken glimpses of the train of one of the meteors through the
grim dark pillars of that ruin of most successful manufacture, the
National Monument; and in fact from no point in or out of the city was
it possible to watch the strange rain of stars, pervading as it did all
points of the heavens, without pleased interest and a kindling of the
imagination, and often a touch of deeper feeling that bordered on awe."
At London about 1 o'clock a single observer counted 200 in two minutes.
The whole number seen at Greenwich was 8485. The shower was also
observed in different countries on the continent.
[22] The first indication of the approaching shower was the appearance
of meteors in unusual numbers at Malta, on the 13th of November,
1864. In 1865, as observed at Greenwich and other stations, they
were still more numerous.
In 1867 the display was generally observed throughout the United States.
From the able and interesting reports of Commodore Sands and Professors
Newcomb, Harkness, and Eastman, we derive the following facts in regard
to the shower as seen at Washington, D. C.:
Commencement 1_h._ 0_m._ A.M. Nov. 14.
Maximum 4 20 " "
End 5 0 " "
Number of meteors per hour at maximum 3000
Mean height on first appearance 75 miles.
" " on disappearance 55 "
Position of radiant, R. A. 151°, Decl. 22-1/2°.
The shower of 1868 was in some respects quite remarkable, though the
number of meteors was less than in 1866 or 1867. At New Haven the fall
commenced about midnight, and from 2 o'clock till daybreak over 5000
meteors were counted. The time of maximum could not be accurately
determined, as no decrease in the numbers was observable till dawn. The
display was also witnessed in England and in Cape Colony, South Africa.
The times of maxima in these countries differed so materially as to
indicate a decided stratification of the meteoric stream. The entire
depth, moreover, where crossed by the earth in 1868, was much greater
than at the part traversed either in 1866 or 1867.
In 1869 the shower was observed at Port Saïd, Lower Egypt, by G. L.
Tupman, Esq.; in Florida, U. S., by Commander William Gibson, U.S.N.;
and at Santa Barbara, California, by Mr. G. Davidson and Mrs. E.
Davidson. The first observed 112 meteors in 1h. 54m., from 2h. 30m. to
4h. 24m., Alexandria mean time; the numbers during this interval being
nearly equal, though slightly decreasing. Throughout the morning
(November 14) the sky was only partly clear. The two observers at Santa
Barbara saw 556 in 2h. 25m., ending at 3h. 43m. A.M. In Florida also the
display was quite brilliant, though inferior to that of 1868. It should
be remarked that the morning in many parts of the United States was
cloudy. No considerable number of the meteors of this stream has been
observed in any part of the world since 1869.
DISCUSSION OF THE PHENOMENA.
Since the memorable display of November 13, 1833, the phenomena of
shooting-stars have been observed and discussed with a very lively
interest. Among the first laborers in this department of research the
names of Olmsted, Herrick, and Twining must ever hold a conspicuous
place. The fact that the position of the radiant point did not change
with the earth's rotation at once placed the cosmical origin of the
meteors wholly beyond question. The theory of a ring of nebulous matter
revolving round the sun in an elliptic orbit--a theory somewhat
different from that proposed by Olmsted--was found to afford a simple
and satisfactory explanation of the phenomena. This hypothesis of an
eccentric stream of meteors intersecting the earth's orbit was adopted
by Humboldt, Arago, and others, shortly after the occurrence of the
meteoric shower of 1833.
A few years previous to the display of 1866 it was shown by Professor
Newton, of Yale College, that the distribution of meteoric matter around
the ring or orbit is far from uniform; that the motion is retrograde;
that the node of the orbit has an annual forward motion of 102´´.6 with
respect to the equinox, or of 52´´.4 with respect to the fixed stars;
that the periodic time must be limited to five accurately determined
periods, viz.: 180.05 days, 185.54 days, 354.62 days, 376.5 days, or
33.25 years; and that the inclination of the orbit to the ecliptic is
about 17°. Professor Newton, for reasons assigned, regarded the third
period named as the most probable. He remarked, however, that by
computing the secular motion of the node for each periodic time, and
comparing the result with the known precession, it was possible to
determine which of the five periods is the correct one.
For the application of this crucial test,--a problem of more than
ordinary interest,--we are indebted to Professor J. C. Adams, of
Cambridge, England. By an elegant analysis it was first shown that for
either of the first four periods designated by Professor Newton, the
annual motion of the node, resulting from planetary perturbation, would
be considerably less than one half of the observed motion. It only
remained, therefore, to examine whether the period of 33-1/4 years would
give a motion of the node corresponding with observation. Professor
Adams found that in this time the longitude of the node is increased 20´
by the action of Jupiter, 7´ by the action of Saturn, and 1´ by that of
Uranus. The effect of the other planets is scarcely perceptible. The
_calculated_ motion in 33-1/4 years is therefore 28´. The _observed_
motion in the same time, according to Professor Newton, as previously
stated, is 29´. This remarkable accordance was at once accepted by
astronomers as satisfactory evidence that the period is about 33.25
years.
Having determined the periodic time, the mean distance, or semi-axis
major, is found by Kepler's third law to be 10.34. The aphelion is
consequently situated at a comparatively short distance beyond the orbit
of Uranus. The orbit is represented in Fig. 4.
[Illustration: Fig. 4.]
It was stated at the close of Chapter VI. that shooting-stars are the
dissevered fragments of cometic matter, which, penetrating our
atmosphere, are rendered luminous by the resistance so encountered. The
discovery that comets and meteors are actually moving in the same orbits
was first announced by Signor Schiaparelli in 1867. The coincidence of
the orbits of Tempel's comet[23] as computed by Dr. Oppolzer, and the
meteors of November 14 as determined by Schiaparelli, is too close to be
regarded as merely accidental. These elements are as follows:
Nov. Meteors. Tempel's Comet.
Perihelion passage Nov. 10.092, 1866. Jan. 11.160, 1866.
Passage of descending node Nov. 13.576,
Longitude of perihelion 56° 26´ 60° 28´
Longitude of ascending node 231° 28´ 231° 26´
Inclination 17° 44´ 17° 18´
Perihelion distance 0.9873 0.9765
Eccentricity 0.9046 0.9054
Semi-major axis 10.3400 10.3240
Periodic time 33.2500 _y._ 33.1760 _y._
Motion Retrograde. Retrograde.
[23] See page 30.
The fact is thus obvious that the meteors of November 14 are the
products of the comet's gradual dissolution. It has been stated that the
comets of 1366 and 1866 are probably identical. The interval indicates a
period of 33.283 years--greater by 39 days than that found by Oppolzer.
With this value of the periodic time and the known secular variation of
the node it is found that the comet and Uranus were in close proximity
about the beginning of the year 547 B.C. It is therefore not improbable
that the former was then thrown into its present orbit by the attraction
of the latter. The celebrated Leverrier designated the year 126 of our
era as the probable epoch of the comet's entrance into our system. This
date, however, is incompatible with the period here adopted. It is
worthy of remark, moreover, as bearing on this question, that the
extension of the cluster in the tenth century, as indicated by the
showers of 902, 931, and 934, was too great to have been effected in so
short a period as 800 years.
With the period of 33.283 years it is easy to find that the comet will
make a near approach to the earth about the 16th or 17th of November,
1965, and to Uranus in 1983. At one of these epochs the cometary orbit
will probably undergo considerable transformation.
We have seen that the comet of 1866, and also the meteoroids following
in its path, have their perihelion at the orbit of the earth, and their
aphelion at the orbit of Uranus. Both planets, therefore, at each
encounter with the current not only appropriate a portion of the
meteoric matter, but entirely change the orbits of many meteoroids. In
regard to the devastation produced by the earth in passing through the
cluster, it is sufficient to state that, according to Weiss, the meteor
orbits resulting from the disturbance will have all possible periods
from 21 months to 390 years. It may be regarded, therefore, as evidence
of the recent[24] introduction of this meteor-stream into the solar
system that the comet of 1866, which constitutes a part of the cluster,
has not been deflected from the meteoric orbit by either the earth or
Uranus.
[24] Recent in comparison with the origin of the August meteors,
which constitute a continuous ring.