The L'Anse sentinel. (L'Anse, L.S., Mich.) 18??-current, 1892-07-23
ABOUT COMETS TAILS.
THERE ARE THREE KNOWN
VARIETIES OF THEM.
Some OF Them More Than Hundred
Million Miles in Length-The
Streaming Appendage Must
BE Constantly Fed.


We call the coma Generally. that
characteristic feature the tail. 10 not
to be seen at first The exact nature
Of a comet is not as yet fully l<noVn..
but In 8 gene ral way A. is luppossd to
be composed Of a swarm % soiid par
ticles Of an unknown size end widely
separated. "
Each particle carries with it an en-
velope OF hydro-carbon gas which
gas light Is produced either by cleo
trical discharged between. the parti-
cles or by some other lightevolving
action due to the suns influence.
This Is before the comet puts forth a
tail which is done only as 1t ap-
proaches the sun. The interesting
process OF putting 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 liber-
ated gas Is supposed to be electrified
by the sun, and the similar electricity
in the sun repels the gas and drives it
off into space in an opposite. or near
ly opposite. direction. allowing for
the movement OF the comet in its
orbit
1t may BIO Lews TO some people that
there are three distinct types OF COM
cts tails. says the Boston Journal. and
that first class well-equipped comet
one that really pretends to style. may
display all OF the varieties The
ordinary form OF tail is of hydro
carbon nature. and its spectrum
when examined with the spectroscope
is similar to that OF oliticant gas.
which is pra .t:cally abolt the same
thing as common burning gas. Then
there is the hydrogen tail" straight
tail, T" which is the shortest and stub
best 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 attraction draw
ing it toward the sun.
Therefore the hydrogen particles
leave the comet with relative veloc-
ity OF at least four or five miles a
second. and this velocity increases as
they recede until at last it becomes
enormous the particles travelling sew
eral million miles in day. The
Iron" tail the short stubby brush
like kind. is due to matter upon which
the repu!sive force from the sun is
only from one tenth 10 ono half that
OF the sravitational attraction. The
hydro. carbon tail curved aud plume.
like 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 he tail as 1t
goes streaming off into space requires
constant replenishing. The tail OF
one time is not the tail of another;
1t varies like the steam from a sea-
kettle which presents a fairly close
analogy. 1t is an expensive affair s,
keep up tail millions OF miles long.
For this reason the longer a comet is
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 ut all.
Talk of Hamlet with Hamlet left out.
The tail as we have seen is 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 natur-
ally looks fainter than the edges
And now as to the length OF co NETS
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 10. 600. 900 or 49,
600. 900 miles and frequently reaches
from 30. 600. 900 to 80 900. 900 miles
In many cases 1t has been known to
exceed 100. 600. coo miles and at the
end to be several million miles across.
The great comet OF 1882 had a tail
more than 100. 600 600 miles long.
about 200. 600 miles in diameter al the
comets head and diameter OF 10, O00-
900 miles out at the end. A pretty
good sized gas jet that This comet
went around the sun through perihe-
lion-that is the point in its orbit
nearest the sun--with a velocity OF
more than $50 miles second, almost
grazing the suns surface.
WComets are supposed to come from
outer space. far beyond the limits OF
the solar system. Many OF them do
not feel the force of attraction, or at
least do not respond to it. Those
that are attracted into our solar sys-
tenn 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. II. however. the sum total
OF the retardations OF the solar sys-
tenn exceeds that OF the acceleraeions
the comet is captured and becomes
permanent member OF our solar sys-
tenn. The parabolic orbit in this
case becomes closed into an eclipse.
There are permanent members OF the
solar system whose periods vary from
u few to hundreds OF years Thus
the period OF the great comet OF 1882
Is about $50 years that OF the great
comet OF 1858 about 1. 958 years.
Speaking OF the comets which have
been drawn into our solar system. IL
Is known that Saturn has captured
two. Uranus three. Neptune six and
v.,n - Al.