The Columbia herald. [volume] (Columbia, Tenn.) 1850-1873, 1872-09-27
The Giant Planet.

Jupiter has diameter exceeding the
earth's rather more than ten times, and
a volume exceeding hers go times.
tt is not far from the truth to say that
Jupiter,s dimensions exceed the earth's
in very nearly the same degree that
those of the sun exceed Jupiter's. But
this mass, though gigantic compared
with the earth's does not altogether cor
respond to his bulk, for it exceeds the
mass of the earth only 800 times. so
that, if the disc our astronomers see
and measure actually represents the
true globe of the planet, his substance
must be, on the average, much less
dense than that of the earth. In fact,
while the earth's density Is nearly SIX
times as great as that of water, the den
sity of Jupiter thus judged) would ex-
ceed that of water barely one third.
This vast globe rotates in less than
ten hours, on an axis nearly upright or
square to the level in which the planet
travels. This rapidity of rotation-so
great that points on heplanet's equator
travel twenty-seven times as fast as
points on the terrestrial equator-re-
suits in q considerable fattening OF the
planets globe insomuch that the po-
lar diameter is less than the equatorial
by about twentieth part, or by fully
1000 miles. And it may be remarked,
in passing that, this circumstance, the
fact. namely, that the poles of the plan
ct are drawn in, as it were, $500 miles
as compared with the equatorial regions,
or 1.75O miles as compared with the
mid -latitudes in either hemisphere, al
fords o striking illustration OF the enor-
nous amount of energy really represent
ed by the rotation of Jupiter. 1t may
also be added that the velocity with
which points on Jupiter's equatoriaf
zone are carried round exceeds the cor
responding velocity in the case of all
the planets in the solar system, ana Is
nearly six times greater than the equa.
torial velocity of the sun itself. LII
amounts, in fact, to about seven and
half miles per secondI
We do not propose to consider mere
at any length the system OF sateiiites
over which Jupiter bears sway out
this preliminary sketch would belncom-
plete without a few words on the sub
iect. 1t is worthy of notice that al
thouph our earth in some sort resem-
bles the outer planets in being accom-
panied by a satellite, yet the relation
which the moon bears to the earth Is
altogether different from that which the
satellites of the outer planets bear 10
their respective primaries.
Our moon is by no means a minute
BODY by comparison with the earth, and
compared with Mars or Mercury she
NAV be regarded as having very respee-
table dimensions. We may, indeed,
leok upon the moon as fifth member
of the family of planets-a member IN,
ferior to the rest, doubtless, but still
not as far inferior to Mercury as Mercu-
nv is inferior to the earth. In the case
OF the cutter planets, and especially IN
Jupiter's case, moons hold an utterly
subordinate position. Taking the ac-
cepted measurements. we find the larS-
est of Jupiter's moons less than the TO-
OOOth part of its primary as respects
bulk, while its mass or weight Is less
than the II, ,OOOth part of Jupiter's. so
that these orSs may fairly be regarded
as bearing the same relation to their
primary that Jupiter himself bears to
his primary-the sun.-Cornhiu Mag
z;np