Gold Hill daily news. [volume] (Gold Hill, N.T. [Nev.]) 1863-1882, 1865-01-31
Abeut Comets.

Ihe matter or Wnlcn cOHlets arc
composed is still subject Of inquiry
among astronomers. But enough is
known to establish the fact that there
islittle danger Of serious consequences
even from an actual collision between
the comet and the earth, The tail
Of the comet is certainly as impon-
derable as light, and bears a striking
resemblance to the streemers OF the
aurora borealis. Newton considered
that the tail Of great comet might
be compressed into the bulk Of a sin.
gle cubic inch before it would equal
the density Of our atmosphere. Sir
J. Herschel supposed that it does
not contain more than a few pounds
or ounces Of matter. Indeed, there
is reason to believe that the earth
passed through the extremity Of the
tail of the comet of 1861, with no
other effect than an auroral glare,
noticedby various observers. The in
conceivable attenuation of the tail of
a comet is such that it would not
offer the slightest resistance to the
passage of the earth and its atmos-
pherc. Nor is the nucleus or main
body of a comet much more formida-
Bile. 1t is not solid, but is what as
tronomers term nebulous; but whe-
ther this nebulosity is gas, or vapor.
or matter more condensed, is not de-
termined. 1t is generally believed
that its substance is not denser than
a cloud. Sir John Herschel was
able to distinguish stars as minute as
the, 10th or 18th magnitude through
the body of a comet! A collision
with a cloud would be as formidable
as with body 50 attenuated. The
question whether comets shone with
direct or reflected light was long in
dispute, but recent investigations
show that the light of comets is po-
larized, and is therefore derived from
the sun. The term .'fery visitants"
applied to them is, therefore, a misno-
mer. s5 sr -.... .-.-....
That comets have little ponderosi-
ty, is proved by the fact that they
exercise no disturbing influence upon
the planets in their motions, although
often coming within their influence.
Bicla's comet in its periodic returns
passes very near the earth's orbit
in 1882 it actually crossed it-but
there is no evidence that it has ever
caused the slightest perturbation
that it has retarded or advanced the
earth's annual motion single second
Of time. The remarkable comet of
ITO which was found by Lexell to
revolve in a moderate ellipse, in
period of about five years, actually
got entangled among the satellites of
Jupiter, and thrown out Of its orbit
the attractions of that planet, has not
been heard of since. Yet the small
est of the satellites of Jupiter was
not disturbed in its course by the in
truder. 'H .'. 1t. ' .'
1t is hardly worth while to discuss
the chances of collision with bodies
go imponderable, though this has
been done. The French govern
ment, when the near approach Of
Biela's comet caused so much alarm,
called the attention of its ablest ma
thematicians and astronomers to the
solution of this problem, 1. e. to de-
termine, upon mathematical princi-
Piles, how many chances Of collision
the earth was exposed to. After a
mature examination they reported:
awe have found that, of 2Sl,C0O,-
600 of chances, there is only one un-
fayorable-there exists but one which
can produce collision between the
two bodies" s-.. brf ~...sar