Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1882-02-26
THE EARTH and THE COMET.
PROFESSOR CHARLES a. YOUNG SAYS
THERE is NO REASON FOR ALARM.
Reasons for Believing that the Fall Upon
the Sun Of Mr.. PrOctOr's ,tsnac.ng
Comet Would Not Produce DISASTROUS
Effects-The Comets Identity Not Estab-
New York Sun, 23d.]

Menacing Comet" in his new book of
scientific essays has attracted great dead
! of attention, especially since the most in
teresting part of 1T was printed in the
.Su,a of Monday. The notion that the
earth may be put in danger from comet
is not a new one. Great comets have
always excited dread by their appear
and in old time the popular belief was
that they were sent to burn up
the world. The failure of each
comet in succession to do the earth any
harm seemed to have little effect in allay-
| ing the fears of the ignorant and super
stitious, and the same terror followed the
appearance of every new comet. In
modern times the fear of comets has
diminished about IN proportion to the
spread of intelligence, although even as
tronomers have, at all times, predicted
possible danger to the earth from these
visitors from outer space. Most people
had about settled down into the belief
that great comets look much more formi-
dable than they really are, trusting to the
assurance of the astronomers that there
was no danger. But now comes an as
tronomer, one of themost widely known,
too, and suggests that the earth may be
put in peril even before the end OF this
century.
Mr.. Proctor's statement is in substance
this: Careful mathematical calculations
have led to the belief that the comet seen
in the southern hemisphere early in the
wear lSSO-it was not visible in this hemi-
sphere, but was well seen in South Amer
lea and at the Cape of Good Hopes
Identical with the great comet OF 1S43,
and also with comet that appeared in
1868. All of these comets were remark
able for the closeness of their approach to
the sun. 1t is believed that they must
have passed through the SUMS
corona, and as this would have
a retarding effect upon them,
the inference, supposlng them all
to be one and the same comet, is that the
period of revolution, which was IT'S years
between 1868 and 1S43, was reduced to 81
wears between lS43 and 1880, and that it
must have been still further reduced in
1880, so that the comet may return about
1897. and, after one or two circuits, fall
into the SIM. Mr.. Proctor's idea is that
if big comet should fall into the sun
the conversion of its immense momentum
into heat would fire up the sun to such a
degree that no living thing upon the
earth could survive. He believes that
other suns have thus been caused to burst
out with extraordinary brilliancy by the
downfall of comets upon them.
In order to show what other astrono-
mers think of this, and what ground
there is for Mr.. Proctor's statements,
Prof. G. A. Young of Princeton college,
who is one of the foremost of living as
tronomers, was asked yesterday to give
his opinion on the subject to the Sun.
Prof. Young said he had great respect
for MIR. Prector's ability and versatility,
and his understanding of astronomical
subjects; but he could not accept his con-
illusions as to the earth being endangered
by the fall of comet.
sIn the first place." Prof. Young said,
"the identity of the comets of 1865, 1S43,
and 1880 cannot be regarded as
established. The evidence of iden-
tity is rather small, and the re-
semblance of the orbits may be explained
on the supposition that, they belong to
SO-CdllCu 1duully VI S1OoP Va NOhASto3 VI
are sister comets, like the two into which,
before its final disappearance. Hook
found five or six groups Of such comets
pursuing paths that run close together,
and which appear to belong to one fam
ily. Of course, if the identity OF the
comet of 1880 with the others is not es-
tablished, there is no evidence OF short
ening of period, and so the bottom OF the
argument falls out.'
"But suppose comet should fall into
the sun; would the effect be disastrous
to us?''
81 think not; There is no known comet
whose mass is sufficient to cause by its
downfall so great an increase of the SUMS
heat as would be necessary to destroy all
living things on the face Of the earth. |
believe Prof Pierce's estimate of the av-
erage comets mass az equal to that of a
solid ball of iron 100 miles in diameter to
be quite generous. | should be inclined
to place the estimate lower. But even it
we accept Prof. Pierce's opinion we see
that the average mass of comets would
not be equal to one one hundred-thous-
andth of the mass Of the earth. Now, il
the earth should fall into the sun. it would
generate enough heat to keep the sun
running at its present rate of radia-
ton for about 100 years, that is suppOsing
the present supply to be in the meantime
cut off. 1t follows, therefore, that the
fall into the sun of a mass, such as we
have taken to represent comet, would
generate only enough heat to keep the
sun running for something like four
DAYS. To put it in another way, if the
heat of the collision we're emitted within
four days after the fall, the SUMS radia-
ton during that time would be about
doubled. These estimates, of course, are
only approximate, but they are near
enough for our present purpose. But, in
fact, the effect of the collision would not
be mainly felt in an immediate increase
of the radiation Of heat from the sun.
There might, at first, be a flash Of heat
which observers who were on
the lookout could perceive, but the
community at large would probably know
nothing about it. The greaterportion of
the increase of energy resulting from the
downfall of the comet would be expended
| in the sun itself in producing expansion
of the solar orb. In other words it would
be expanded in doing mechanical work
in the sun, and so we really would not
get double supply of heat even for four
DAYS. The added heat would be radiated
out slowly from the sun during ages of
time, and in the case supposed would be
4 L Y