Evening star. [volume] (Washington, D.C.) 1854-1972, 1890-08-11
THE AUGUST METEORs.
A Cloud OF Star Dust Sixteen Million
Miles Thick.

From the Chicago Inter Ocean.
The August meteors are believed to originate
from large cluster or zone Of meteoric bodies,
which revolves around the sun in an ellipticai
orbit, extending far beyond the orbit Of the re-
mote planet Neptune, and through which the
earth plunges annually. II IL also believed by
most astronomers that these bodies are scat
tered over the entire path Of the cluster to
which they belong, but not in equal numbers
throughout. The earth il about ten days in
passing through the entire cluster, which,
from our velocity in space, indicates that the
thickness of the cluster is about i6, 600 900
miles. As the annual August display usually
lasts about six hours, and the earth travels at
the rate OF $1,000 miles per hour, or eighteen
miles a second, it follows that the breadth Of
the meteor stream at the place where the earth
crosses it, dense enough to produce me
teoric shower" is over 400 900 miles. On Au-
gust 10 each year the earth encounters the
eiiipticai orbit of this me teoric cluster, the
major axis of which is fifty times greater than
the mean diameter of the earth's orbit; the
orbit Of the meteors is greatly inclined to that
OF the earth, and their motion is retrograde, or
contrary to that Of the earth.
The density of the meteoric cluster-or
stream, as some astronomers call it's believed
to be quite small, the average distance Of the
u
puted to be more than 100 miles. from which
circumstance and the fact, already mentioned,
that the stream Is spread around the entire
orbit, Prof. Newcomb Of the United States
Naval Observatory recognizes decided indica-
lions of antiquity in the August meteor stream,
as compared with the November cluster, 80
that We can say, with considerable probability,
that the August group has been in our system
at least twenty times longer than the Novem-
Der group" Prof Swift in referring to the
August meteOric display, says: 1.-The first Au-
gust shower mentioned In history occurred on
July 26, AID. s11, and has appeared with un-
failing regularity down to our time, except a
break of SO years between 841 and 924. and an
other and much longer one of 80 years be-
tween 1913 and l243, owing, probably, to breaks
IN the ring, or, which is more likely, to fall
ure to record them" There are on record q
large number Of meteoric displays that are be-
loved to belong to the same cluster. and q
comparison of dates affords some indication of
a maximum of brilliancy, recurring at intervals
OF about 10S years.
earth passes through little more than 100 Of
these meteor streams in the course Of its an
nual journey around the sun. Each of these
streams has some particular radiant point"
and belongs to q distinct system Of meteors
Over 100 of these streams have had their orbits
determined by astronomers, and others are
frequently added to the list already known.
From a long series of observations. astronom-
ers have concluded that the earth encounters
about 400.000,000 shooting STRENGTHENING
those that would be seen through the largest
teescopes-during its annual journey around
the sun. 1t is known that shooting
stars are fragmentary masses, revolving, like
the planets, around the sun as a center, which
in their course approach the earth, and being
drawn by its attraction into our atmosphere
are ignited by the heat generated through
friction aud the resistance offered by the COM
nrpGSad n
it enters the atmosphere, when it is heated to
incandescenee-or becomes red hot'--and its
substance is scattered in powder or smoke,
falls to the earth as meteor dust" or floats
about in the atmosphere.
Shooting stars are so called merely from the
fact that they resemble the stars in appear
ance. They enter our atmosphere with a
velocity from fifty to a hundred times that of a
cannon ball, and previous to this they were
dark and invisible, but are almost instantly
ignited after their sudden impact, and entirely
consumed, their dust gradually falling to the
earth. A Russian astronomer has calculated
that 4, $50 pounds of meteoric dust fall to the
earth every hour. which would make SO tons a
day, or more than 81 500 tons in year, while
Prof. Proctor considers even this estimate too
small. "Aii know what shooting star looks
like. but no living man can tell us what it really
Is, for not one has ever been known to reach
the earth" The singular fact has been de-
monstrated that while the most rapid cannon
shots scarcely attain q velocity of 600 meters q
second-over ], 500 miles an hour--me teorites are
known TO penetrate the atmosphere with veloc-
ity of 40 600 or oven &C, 900 meters per second,
and the motion of ordinary shooting stars il 80
extremely rapid that they are consumed and
scattered in smoke before they have time to
reach the earth. Prof. Swift says: ~ shoot
ing star is only visible while undergoing the
process of combustion, which lasts from one to
three seconds, seldom longer. Only while be-
ing burned are they visible to US, as then they
shine by their own light Shooting stors move
i'll all directions, and at velocities probably
equal to the earth's-nearly nineteen miles a
| second. One moving retrograde, therefore
| from east to west), would plunge into the at
| mosphere at relative velocity Of some thirty.
| eight miles a second, and, if allowance be made
| for accelerated motion, caused by the earth's
| attraction probably double that, or seventy
five miles a second. The encounter is fearful
| and but for the atmosphere, which acts as
cushion, the effect would be disastrous for no,
less than 1000, 900 would rain upon the earth
every day.
The actual diameter Of the largest meteor O,
| sire ball" is estimated by Humboldt to vary
| diameter OF about mile. Shooting stars are
much smaller, their weight varying from 81
| grains to pounds Prof Hardness, who has de
voted many years to the study of this subject
| estimates that the average weight of ordinary
shooting stars docs not differ much from one
/
celestial objects may be easily imagined. Shoot
ing stars are the smallest celestial bodies known
to astronomers the majority Of them being nj
| larger than pebble. or grain Of coarse sanl
! even. No line of demarkation can be drawn
between the smallest shooting star and a brill
liant meteor that leaves luminous train be
hind. In fact a meteor" is simply larg,
| shooting STAR" They differ from each othe
| in siZe color, direction, train and velocity, bu
in astronomical character are precisely alike
both moving in long orbits like comets, ant
like comets at all angles to the earth's orbit
Automatically speaking, a meteor is a small
comet, not having. however, the comets ''tail.
| Some meteors are SO large that they fall Il
| the earth as ''aerolites" before the heat pro
duced by friction can convert their substanc
| into vapor. Several have been found, and seeI
| to fall, on various parts of the earth, and
massive specimen weighing 1,635 pounds, O
nearly one ton, is preserved in the museum 0
Yale College.
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