The Republican. [volume] (Oakland, Md.) 1877-current, 1882-03-25
That Threatening Comet.


fiftaen wears hence, was referred to edi-
torially by the Tribune last Sunday. It
4 was devastated that the matter would
he referred to the Tribune astronomer.
The promise was made in a jocular way;
but SO many readers have since expressed
a desire to .'hear from him. on the sub
iect that he has undertaken a 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 1880
were all travelling in nearly the same
path does not prove their identity. But
/ the fact that they Cor it) 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 $4,000 miles Of
what appears to us to be the SUMS nor
NAL surface. The observation of the solar
eclipse of 1869 satisfied the writer that
the sun has an atmosphere which extends
at least 800,0 miles above the apparent
| surface. That is, it extends QUIT 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 100
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 hcat.
1t 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 perihelionretl,rn,
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. If take the SUMS radius
as the unit of measure, then the square
of the velocity on reaching his surface,
plus unity divided by the major axis Of
the orbit, is a constant quantity-the
same for every member of the solar sys-
tenn, except small variation due to the
quantity of matter in the falling mass.
With this we may calculate that a para
bolic orbit would give greatest velocity
of 1922 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 382miles If, therefore,
the orbit of the comet should be short
ened down by two or three more peri
helion passages before the final collapse
we should still have maximum velocity
of about 3S0amiles. This would be con-
verified into heat. Dividing this velocity
by 223 feet, and squaring the result, we
obtain, in round numbers, 80,000,000
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. 'H A.'
The next important point is to know
the quantity 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.
And 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
solid 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
Iocitxy II docs r,,atarial II II laccop tba oman
tity of matter that is left to be heated up
by 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 i'm
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 outburstof 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 a 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 atmosphere with all the ma
terial requisite to deluge of rain, that
I 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
of changes would be repeated, on a di-
minishing scale, several times at intervals
49, IL Il. II. Il