Rock Island daily Argus. (Rock Island, Ill.) 1886-1893, 1892-06-28
THE TAILS OF COMETS
THEY ARE MADE BY THE SUMS HEAT
AND CONSIST OF GAS.
In Fact, the TAN of a Comet Is Nothing
More Than an Almost Uncomfortable
Gas DISSEMINATING About the Length
of These Rem irkable Phenomena.

y comet when first seen is generally a
| small, round object, with q nucleus or cen
| tral condensation surrounded with halo
| Of light, which we call the coma Gener-
| ally that charaCt eristic feature, the tail
is not to be seen At first. The exact nature
of a comet is not as yet fully known, but
| in a general way it is supposed to be COM
| posed of 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 infiu-
ence. This is before the comet puts forth
! tail, which Is cone only as it approaches
the sun. The interesting process of put
| ting forth 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 he electrified
by the sun, and tie 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 its orbit
1t may be news to some people that there
are three different types of comets tails,
and that a first class well equipped comet,
one that really pretends to style, may dis
Of tail is of hy6rocarbon nature, and the
spectrum, when examined with "a spectre
scope, Is similar 70 that of olificant gas,
which is practically about the same thing
as common burning gas. Then there is
the hydrogen tail" straight and long and
slender, and the iron tall 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 gravitatonal attractions drawing it to-
ward the sun.
Therefore the hydrogen particles leave
the comet with a relative velocity of at
least four or fives miles second, and this
velocity increases as they recede until at
last 1t becomes enormous the particles
travelling several million miles 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 plumelikc, 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 or into space requires constant
:eplenishing. The tail of one time is not
the tail of another; it varies like the stream
from teakettle, which presents fairly
close analogy. Ii is an expensive affair to
keep up tail millions of miles long For
tins 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 ont The tai wa bova
formed by the gas on the side nearest the
sun 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
lO,000,000 or 1900 900 miles, and frequent
ly reaches from 10000, 900 to $1,000 900
miles. in many cases it has been known
to extend 100000, 100 miles, and at the end
to be several million miles across. The
great comet of lSS2 had tail more than
lOO,en,epO miles .Ong, about 100000 miles
III diameter at the comets head and a
diameter of 10000 COO miles out at the end.
A pretty good sized gas Jet, that, This
helion-that is, tie point in its orbit near
est the sun-with a velocity of more than
$50 miles second, almost grazing the sum.
surface.
Comets are supposed to come from out..r
space far beyond the limits of the solar
system. Many of them do not feel the
force of our attraction, or at lest do not
respond to it. Those that are attracted
into our solar system pass around the sun
IN orbits, mainly of he 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 permanent member of our
solar system. The parabolic orbit in this
case becomes closed into an eclipse. There
are permanent members of the solar svs-
| TEN 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 1855 about $50
| years.
Speaking of the comets which have been
drawn into our solar system, it is known
| that Saturn has captured two, Uranus
| three, Neptune six and Jupiter some six
| teen. Sometimes comet separates or
| splits into two parts. Such was the case
| with Biela's comet, discovered in 1926 I,
comet whose orbit comes near that of the
| earth. On its return in 1916 it had divided
| into two parts, which parts travelled along
| side by side for more than four months,
being about 10000 miles apart. On the
comets next ret Urn, in 1852, both parts
were seen, but they were 100000 miles
I, asunder. and neither part has been seen
| since.
The connection between comets and the
| phenomena of shooting stars is very in
| teresting one. At present 1t is supposed
| that certain showers of shooting stars
either come directly from comets or from
swarms of particles moving in the same
orbits with them.--Boston Journal
The Missing Link.
| All this tall alnut rapid transit G rpla-