THE PLANET JUPITER.
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apparent size of Jupiter, ” which naturally suggested thequestion,—Is what we see really the boundary of the planet ornot? It may, however, be well, before we indulge in anyfurther discussions of a similar character, to state a few factswhich have been certainly ascertained with regard to thedimensions of the planet and of its orbit.
The surface of the globe, seen by us, which (whether it moreor less exceed in size the real body of the planet) is all thatwe can measure, is about 120 times that of the Earth ; morethan 6,000 times that of Europe ; and more than 400,000times that of England.
Fig . LXIV.—The polar flattening of Jupiter is such that one-half.of the planet Mars placed,
r- as in this figure-, at one of its- poles would lie 500 miles within a sphere cf a radius
equal to that of Jupiter ’s equator.
miles.* But the polar diameter is more than 5,000 milesshorter, the proportionate difference being greater than in thecase of any other planet, except Saturn .
So vast is the size of the apparent globe of Jupiter , and soconsiderable the amount of its polar flattening, that, if adiagram be carefully drawn to scale as in Fig. LXIV., and theshape, which one-half of a circular disc of the same diameteras its equator would have, be indicated by a dotted line, thedistance between one of the poles of the real disc and thedotted semi-circle would more than suffice to receive one-halfof the disc of the planet Mars . In fact, between the centre
* The above value assumes the Sun’s distance from the Earth to beabout 93,000,000 miles. If that distance be greater, the apparent widthof Jupiter ’s disc will represent a proportionally greater diameter, and viceversa.