y the quarter of our own; but weight is
twice and a half times as great there as here. The constituents of
things and beings are thus composed of materials lighter than those upon
the Earth; but, as the planet exerts a force of attraction twice and a
half times as powerful, they are in reality heavier and weigh more. A
graceful maiden weighing fifty kilograms would if transported to Jupiter
immediately be included in the imposing society of the "Hundred Kilos."

Jupiter rotates upon himself with prodigious rapidity. He accomplishes
his diurnal revolution in less than ten hours! There the day lasts half
as long as here, and while we reckoned fifteen days upon our calendar,
the Jovian would count thirty-six. As Jupiter's year equals nearly
twelve of ours, the almanac of that planet would contain 10,455 days!
Obviously, our pretty little pocket calendars would never serve to
enumerate all the dates in this vast world.

This splendid globe courses in space at a distance of 775,000,000
kilometers (480,500,000 miles) from the Sun. Hence it is five times
(5.2) as remote from the orb of day as our Earth, and its orbit is five
times vaster than our own. At that distance the Sun subtends a diameter
five times smaller than that which we see, and its surface is
twenty-seven times less extensive; accordingly this planetary abode
receives on an average twenty-seven times less light and heat than we
obtain.

In the telescope Jupiter presents an aspect analogous to that likely to
be exhibited by a world covered with clouds, and enveloped in dense
vapors (Fig. 45).

It is, in fact, the seat of formidable perturbations, of strange
revolutions by which it is perpetually convulsed, for although of more
ancient formation than the Earth, this celestial giant has not yet
arrived at the stable condition of our dwelling-place. Owing to its
considerable volume, this globe has probably preserved its original
heat, revolving in space as an obscure Sun, but perhaps still burning.
In it we see what our own planet must have been in its primordial epoch,
in the pristine times of terrestrial genesis.

[Illustration: FIG. 45.--Telescopic aspect of Jupiter.]

Since its orbital revolution occupies nearly twelve years, Jupiter
comes back into opposition with the Sun every 399 days, _i.e._, 1 year,
34 days, that is with one month and four days' delay each year. At these
periods it is located at the extremity of a straight line which, passing
by the E