Bismarck weekly tribune. [volume] (Bismarck, Dakota [N.D.]) 1884-1943, 1892-07-22
THE Fl TAILS OF COMETS.
THEY ARE MADE BY THE SUMS HEAT
AND CONSIST OF GAS.

! HEY ARE MADE BY THE SUMS HEAT
AND CONSIST OF GAS.
In Fact, the Tail of q Comet Is Nothing
More Than an Almost Uncomfortable
Gas Jet-Something About the Length
of These Remarkable Phenomena.
A comet when first seen is generally a
small, round object, with a nucleus or cen
tral condensation surrounded with a halo
OF light, which we call the coma. Gener-
ally that characteristic feature, the tail,
is not q be seen at first. The exact nature
of a comet is net as yet fully known, but
in a general way it is supposed to be com
posed of a swarm of solid particles Of an
unknown size and widely separated.
Each particle carries with it an envelope
of hydrocarbon gas, which gaslight is
produced either by electrical discharges
between the particles or by some other
light evolving action due to the suns infu-
ence. This is before the comet puts forth
a tail, which is done only as it approaches
the sun. The interesting process of put
ting forth a tail is due to the action of the
sun, which warns up and liberates the gas
on that side Of the comet nearest to it. The
liberated gas is supposed to be electrified
blythe sun, and the similar electricity in the
sun repels the gas and drives it off into
space in an opposite or nearly opposite di-
rection, allowing for the movement of the
comet in it's orbit.
1t may be news to some people that there
are three diherent types of comets' tails,
and that a first class, we'll equipped comet,
one that really pretcnds to style, may dis.
play all the varieties. The ordinary form
of tail is of II hydrocarbon nature, and the
spectrum, when examined with q spectre.
scope, is similar to that of olif1cant gas,
which is practically about the same thing
as common burning gas. Then there is
the hydrogen tall" straight and long and
slender, and the Iron TAIL" which is the
shortest and stubbiest of the three. The
hydrogen tails, or "wisps," are formed OF
matter OF which the suns repulsive action
IS from twelve to fifteen times as great as
the gravitational attractions drawing it to.
ward the SUM-. 80 '. @t
Therefore the hydrogen particles leave
the comet with a relative velocity of at
least four or ives miles a second, and this
velocity increases as they recede until at
last it becomes enormous, the particles
travelling several million miles a day, The
iron" tail, the short, stubby, brushlike
kind, is due to matter Upon which the re.
pulsive force from the sun is only from
one-tenth to one-half that Of the gravita,
tional attraction. The hydrocarbon tail,
curved plumelike, which is generally the
principal one, is due to matter upon which
the repulsive force varies from once to
twice the force of gravity.
1t will be seen that the tail as it goes
streaming OFT into space requires constant
replenishing. The tail of one time is not
the tail of another; it varies like the stream
from a teakettlc, which presents a fairly
close analogy. 1t is ar expensive affair to
keep up n tail millions of miles long. For
this reason the longer a comet is a member
of the solar system the less tail it is able to
present, and the short period comets which
keep coming around frequently, like
Encke's comet, for instance, have no tails
at all. Talk of Hamlet" with Hamlet
left out! The tail. as we have seen, is
formed by the gas on the side nearest the
u escaping and going around the comet
and away. For this reason the tail is a
hollow conoid and the center naturally
looks fainter than the edges.
And now, as to the length of comets
tails. People generally like to read about
big dimensions, and we can satisfy them in
this particular. The length of a good
large comets tail is seldom less than
100000 or 15,000,O 900 miles, and frequent.
ly reaches from 10000 900 to $4,000, 600
miles. In many cases it has been known
to extend 100, 600, 900 miles, and at the end
to be several million miles across. The
great comet of 1882 had a tail more than
1OO,0OO,000 miles long, about 100000 miles
in diameter at the comets head and a
diameter of 10000. 900 miles out at the end.
A pretty good sized gas jet, that. This
comet went around the sun through peri.
helion-that is, the point in it's orbit near.
est the sun-with a velocity of more than
$50 miles a second, almost grazing the SUMS
surface.
Comets are supposed to come from outer;
space far beyond the limits of the solar
system. Many of them do not feel the
force of our attraction, or at least do not
respond to it. Those that are attracted
into our solar system pass around the sun
in orbits, mainly of the parabolic form.
The larger proportion of comets orbits
are Of this general parabolic form. "a
comet passing around the sun in such an
orbit goes off into space never to return,
If, however, the sum total Of the retarda
tions of the solar system exceeds that Of
the accelerations, the comet is captured
and becomes a permanent member Of our
solar system. The parabolic orbit in this
case becomes closed into an eclipse. There
are permanent members of the solar sys,ss
tenn whose periods vary from a few to hun.
dreds of years. Thus the period Of the
great comet of. 1882 is about $50 years,
that of the great comet Of 1858 about 1880
years.
Speaking of the comets which have been
drawn into u solar system, it is known
that Saturn has captured two, Uranus
three, Neptune elk and Jupiter some six
teen. Sometimes a comet separates on
splits into two parts. Such wa the case
with Biela's comet, discovered in 1880, d.
comet whose orbit comes near that of the
earth. On its return in 1s48 it had divided
into two parts, which parts travelled alonR
side by side for more than four months,
being about 10000 miles apart. On the
comets next return, in 1852, both parts
were seen, but they were 1900, 900 miles;
asunder, and neither part has been seen
since.
The connection between comets and the
phenomena Of shooting stars is q very in.
teresting one. At present it is supposed
that certain showers of shooting stars
either come directly from comets or from