The Iola register. [volume] (Iola, Allen County, Kansas) 1875-1902, 1882-03-24
! That Threateaine Comet

Thai Threatening EAnaef
The threatened destruction Of the earth
by comet falling into the sun, some
fifteen years hence, was referred to edi
torially by the Tribune last Sunday. Il
was then stated that the matter would
be referred to the Tribune astronomer
The promise was made in a jocular way
but SO many readers have since expressed
desire to shear from him" on the sub
Iect that he has undertaken response
There is certainly some reason to think
or fear, that the comet referred to will
really fall into the sun. The mere fact
that the comets of 1868, 1843 and 1886
were all travelling in nearly the same
path does not prove their identity. But
the fact that they Tor iD nearly grazed
the surface of the sun at the nearest ap.
proach does furnish good reason to think
that the motion in the curve was thereby
retarded; and the necessary cOnse.
quence of such retardation must be a final
destruction of the orbit. The comet OF
1843 passed within about 80, 900 miles OF
what appears to us to be the suns nor
NAL surface. The observation of the solar
eclipse of 1869 satisfied the writer that
the sun has an atmosphere which extends
at least 800, 200 miles above the apparent
surface. That is, it extends out ten times
as far as the least distance OF the comet.
The solar atmosphere must be exceeding
ly rare in that vicinity, but so Is the
-earth's atmosphere at the height OF lOO
miles: and vet we know that the latter
retards the flight of meteOrs SO much as
to warm them up to the luminous point
the motion being converted into heat.
Hts easily shown that the passage through
a resisting medium destroys much more
of the tangential motion than it does OF
that which results from the action of the
centripetal force Hence the orbit bends
inward more rapidly than before. This
means that the comet returns sooner to
the aphelion point, shortening the major
axis of the orbit and the period OF revolu-
ton. If the comet pass through the re-
sisting medium at each perihelion return,
the orbit is soon broken up by the fall OF
the comet into the sun.
1t is easy to Calculate, approximately,
the quantity of heat developed by such a
catastrophe. five take the suns radius
as the unit of measure, then the square
of the velocity on reaching his surface,
'plls unity divided by the major axis Of
the orbit, is constant quantity-the
SAME for every member of the solar sys-
TEN, except a small variation due to the
quantity of matter in the falling mass.
With this we may calculate that para
bolic orbit would give Il greatest velocity
of 1929 miles per second; and if the axis
of the orbit were shortened to equal that
Of the earth's orbit the greatest velocity
would be about 3S2 miles. If, therefore,
the orbit of the comet should be short
ened down by two or three more peri
he!ion passages before the final collapse
we should still have maximum velocity
of about $50 miles. This would be con-
verted into heat. Dividing this velocity
by 223 feet, and squaring the result, we
obtain, in round numbers, $4,000, 900
degrees of the Fahrenheit scale as the
rise of temperature of the falling mass.
A large part of this would be distributed
by conduction among the material COM
posing the sun.
The next important point is to know
the'guantity of matter in the comet; and
that we do not know. But we have sew.
eral indirect reasons for believing that
AT no time has it been more than about
one part in 5000 of the earth's mass.
Aad it is probably now much less than
even that relatively small quantity. The
passage through the suns atmosphere
shears off the gaseous matter of the
comet and its attendant train of meteors,
both of which are left behind by the more
sold nucleus, as the latter rushes away
in its diminished orbit. Hence, though
the shortening of the period does not de-
tract very much from the perthelic We
10 lily, it does materially lessen the guam
tity of matter that is left to be heated up
b. the last grand rush down into the
bowels of the sun.
Now, if we allow the very greatest
possible value for the mass of the comet
Just before it loses its individuality, we
shall find the heat generated by the inn
pact to be just about equal to that thrown
off by the sun during one week. Allow
ing what seems to the writer to be the.
maximum probable value, the resulting
heat would be equal to the present solar
expenditure during not more than two
days, and scarcely less than one. The
result in the first, and worst, case would
be an outburst of solar energy that would
make itself felt on every planet in the
system. Still the magnitude of the effect
would very largely depend upon anoth-
er consideration. If the comet should
strike the sun on the side that is
turned away from the earth, the
point of greatest disturbance, would not
come round towards us for several days;
and during that time large part of the
extra energy would be so much disturbed
that the earth could endure the change
without an entire subversion of the pres
ent order of things. If, on the other
hand, the comet should strike on the
hither side of the sun, the result to us
would be most disastrous. The increased
heat would rarely our atmosphere, max
ing it occupy much larger bulk than
now, and enormously increase the evapo-
ration from ocean, lake, river and dry
land, parching up the latter, probably
drying up all our water courses, even to
the bed of the great lake system, and
loading the atmospheric with all the ma
teriai requisite to deluge of rain, that
would begin to fall by the time the strick
en- side of the sun had been carried away
from us by the solar rotation. That set