The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1897-01-18
TIE GREATEST
OF THE PLANETS
Feculiarities of Jupiter in Com
position, Temperature
and Motion.
How Modern Science Has Tested and
Tracked One of the Remoter
Planets.


one which is specially accessible to our
observations. Jupiter is greater than
either Saturn. Uranus or Neptune, ana
therefore on that account alone IL
would be obviously easier to observe
Jupiter than any OF the other three,
even if they had all been at equal dis
tances from US. Jupiter IS indeed so
vast that If the other planets OF our
system had ali been rolled together
into one, their united volume would not
be so great as is that of Jupiter But
Jupiter also happens to be much nearer
to the earth than are any OF the
other great planets. 1t therefore fol-
lows for a double reason that this vast
globe offers to the terrestrial aSronO-
mer a surprisingly interesting object
whose details he can examine under
exceptional advantages.
We may first put down some numerl-
cal facts with regard to the dimensions
of this splendid globe and the track in
which il moves. Like all the other
planets, Jupiter of course revolves IN
an elliptic path around the central
luminary. The average distance OF the
great planet from the sun IS 49,, O00,OO0
miles. The course which he follows
is therefore rather more than five
times as great in diameter as IS the
path pursued by the earth. The clip
tic track of jupiter however departs
appreciably from the circular form m
aSmuch as we sometimes ind the as
lance of the planet from the sun to be
as great as 5.45 and sometimes as little
as 4.95, if in each case we take the
average distance from the earth TO the
sun as the unit.
The most favorable circumstances
for observing the planet Will be found
when the earth lies directly between
the sun and Jupiter while a the same
time the earth is at its greatest
possible distance and Jupiter at its
least possible distance from the sun
But even on the rare occasions when
these conditions are fulfilled, Jupiter
must still be nearly four times as far
from the earth as the earth is from the
sun.
JUPITER A SLOW PLANET IN HIS
ORBIT BUT SMART ON
HIS AXIS.
It Is rule in the celestial move
ments that the more distant IS the
track OF a planet from the sun the
slower is the pace at which the orb
moves forward on its mighty journey.
The earth has 10 hurry on al the rate
of Is miles a second in order TO accom-
pliSh its journey round the sun within
the allotted year. But Jupiter, though
it has a much longer circuit 10 accom-
plish is much more leisurely in its pro-
cedure The great planet in fact
This no doubt seems a very high speed
when measured by our ordinary stand
ards Of velocity. such as those pos
sessed by express trains or rife bullets.
There is however another way of judg-
ing the speed of a planet which iT
perhaps more appropriate to the case
than any comparison with the move
mentS of relatively small objects like
railway trains of rife bullets. Let US
think Of the time that jupiter would
require to move through the length Of
his own diameter. The equatorial di-
ameter of the planet is $500 miles, be-
ing about IL times tr81 ~ -
As Jupiter moves about eight miles per
second. or about 4S0 miles Dei minute.
it is easy to see that the planet re
QuireS a period of not less than three
hours to move through distance
equal to its own diameter. Looked ar
in this way the speed of Jupiter seems
slow enough. We should not consider
q missile TO be moving quickly which
required three hours TO advance
through a distance equal 10 its own
length
one Of the most remarka BILE features
connected with the great planet is the
abnomally high speed at which he rO-
tateS around his axis. NotWithStand-
ing the hige bulk of Jupiter we find
that he requires much less time to &C
complish q revolution than does the
Earth. For while our GLOBE takes about
- hours to complete each turn I'VE see
that Jupiter goes round in less than
half the same time. Indeed the periOd
of rotation OF the great planet is not
more than hours 5jI2 minutes. With
this rapid spin about his axis another
remarkable Tea ture Of the planet IS
connected. 1t is obvious TO anyone who
looks at Jupiter through good tele-
scope that the form of the planet is
not circular. The great orb is bulged
out at the equa tor and it is hattened
at the poles. The figure of the Earth
il viii be remem bereG manifeStS feat
IRE of the same kind. But the depart
ure from the circular outline is much
more pronounced in the great planet
than in our own Forth. This certainly
depends upon the high speed at which
jupiter reVOlVeS. The planet not be-
ing made Of solid Materials but rather
Of substances which for the present we
may speak of as plant, gradually
Yields TO the centrifugal action con
nected with its rapid rotation. The
equatorial regions are consequently
bulged out and thus the characteristic
form of Jupiter finds its explanation.
The most noteworthy feature of Jul
piter as wen as each Of the ether eN-
terror planets is the apparently case
Gus character which they exhibit In
this respect they are sharply con-
trasted with the robust globes OF which
our Earth IS the type This point IS so
fundamental that unless it be under
stood the actual appearance of the
great planet viii be hardly Ineligible.
JUPITER'S WEIGHT.
Among the most remarka bic achieve
ments OF astronomers an important
place must be assigned to their dis
ccvery of the weight of the planets.
AT first it might seem q problem of
almost insupera bic difficulty to ascer-
tain the tons or rather the myriads of
tons of matter in a globe situated al
such a distance from the Earth as is
the planet Jupiter. But the fact is
that such a problem can be solved With
all needful accuracy. We now know
the mass of the planet Jupiter certainly
TO within hundredth part. and prob
a bly, to within the thousandth OF its
total amount. 1t seems useless for our
purpose to express this weight in bill
lions of tons; it viii suffice if we com
pare the weight OF Jupiter with The
weight of the Earth. The result is
that we find Jupiter weighs as much
as 80 bodies would do if each OF them
had the same mass as the Earth.
But though, no doubt, this illustrates
in an impressive manner the great
mass of the biggest planet of our sys-
fem. vet from other points Of view
il seems matter Of surprise that the
mass of Jupiter should not have turned
ont 10 be even greater than is thus in
dicated. For knowing the average
diameter of jupiter as well as that Of
tho earth it can be shown by a little