The sun., 1890-01-26
Tho Romance of a Comet.

| there can be no departure from perfect uni.
formity in the clockwork Of the Skies" The
study OF the perturbations produced by the
mutual attractions Of the planets upon one
another nevertheless forms one Of the most
important and intricate departments OF
astronomy. When we come to look at the
| solar system as family OF globes,
all under the dominance OF the sun
and yet all, 30 to speak, pulling and
hauling upon one another as they swing
| in the yoke OF solar gravitation around their
great attractive centre, we see that none OF
| them moves in smooth ellipse. as the books
| teach, but that all 60 swaying and leaning
| in their courses now little this way and
now a little that way, and by their varying
| attraction even moving the sun, like hub
that fits loosely on its axle. But these dis
turbances Of the planets are small when
measured by the vast distances embraced
In their orbits. and can only be detected by
careful observation.
With comets the case is different. Their
mass, even in comparison with the smallest
planets, is so inconsiderable that the effects
OF their attraction upon any planet are i'm
perceptible; but, on the other hand, the at
traction of the planets upon them may suf-
fee completely to change the direction In
which they are travelling. This is almost
certain to be the result IL q comet goes very
near to large, planet. With respect to wan
dering comets, the planets constitute we'll
organized police force. Jupiter, the largest
OF the planets has played strange tricks with
several comets that have ventured tco close
to him and his little flock Of moons and Jupi-
ter Is one OF the three chief characters
concerned in the somewhat romantic history
that we are going to relate.
The bright skies OF the past week have
perhaps given astronomers their farewell
plimpses Of q comet that had been lost for
moro than n hundred years when it sud-
denly and unexpectedly made lis appearance
sunward bound last summer This comet,
for there seems to be little doubt Of the
identity, was first seen in ITO. 1t was then
found to be moving around the sun in
small ellipse in a period Of about
five and a half years. 1t completed
only two revolutions in this orbit and
then in 1779 disappeared as suddenly as
it had come. Careful calculations, based
upon its observed motions, showed that
this strange comet had been the sport Of
Jupiter. In the year 1867, while journeying
through space at respectful distance from
the sun, far beyond the reach OF terrestrial
eyesight, and apparently safe from those
perturbing influences that may disturb the
even tenor OF a celestial body'5 existence, it
fell in with Jupiter. 1t was a pretty narrow
escape from an actual collision. The comet
ran in within the orbital distance Of Ju-
piter's outermost satellite. 1t was literally
made a prisoner on the spot; not to Jupiter,
though the giant planet was Its captor, but
to Jupiter's chief the sun. The effect Of Ju-
piters attraction was to throw the comet out
of the broad free curve, the highway OF open
space in which 1t had been travelling, into q
short ellipse having the sun in one OF Its
foci; and in this ellipse the captive was
journeying when discovered from the earth
In ITO. Henceforth Of its own accord it
could not get further away from the sun
than the point where 1t had first encoun-
tered Jupiter. On the other hand, 1t could
not avoid another encounter with Jupiter
whenever it should be in that part OF its
path that lay near the orbit of Jupiter at the
time the planet should arrive in the same
neighborhood. This occurred in 1879, when
the comet had made only two revolutions
intruder, and, apparently thinking the Court
had discharged the prisoner, gave him, like
any disappointed policeman, farewell kick.
But LEXELLs comet, as the adventurer
has come to be called, was not yet done with
the perils and tribulations Of the solar sys-
tenn, into whose apparently well-ordered and
peaceful precincts it had incautiously VEN
tured. Jupiter's kick did not end its trou-
bles. The biggest member of the celestial
police had simply mistaken the intentions Of
the sun. The prisoner was not discharged,
the law Of gravitation still held him in its
grasp and Jove's boost only sent the un-
fortunate comet whirling in new ellipse
vastly larger than the other, with one ex-
tremity extending beyond the orbit of
Saturn but still having the remorseless
sun in the opposite focus. At this juncture
the comet disappeared from the sight of It's
watchers on the earth. Its perihelion dis
tance was now 30 great that 1t could no
longer enjoy the poor privilege OF displaying
tall and SO get some compensation for its
sorrows by frightening the timid inhabitants
of the planets it had fallen among. But the
S.S of the mathematician was upon it, and
his fine science traced its invisible course
IuiOuBn IhO hNaNOLo ohu iOlOoh" LlluL again
1t would fall within the grasp of Jupiter.
That event happened in 1886. Jupiter made
no mistake this time. He recognized the
old offender, and sent him sunward In
hurry; and now the prisoner of space is
treading the galleys once more before the
eyes of men In an elllptical orbit whose
period Is seven years.
The comets woes are not ended yet. The
calculations OF Mr.. CHANDLER show that 1t
will fall In with Jupiter yet fourth time in
1921. Just what Jove's mood will be then
nobody can foretell. Perhaps he will send
1t wandering In a yet moro remote orbit
than its former ono; or he may adopt 1t as
permanent member OF his own family OF
satellites, as nearly happened in 1886. There
is reason to suspect, however. that the comet
will not survive to travel in many more
orbits. for 1t is evident that at their last en-