be nearly of the same length, and the seasons to be
invariable; and how the amount of light and heat received by the planet
is only a twenty-fifth part of that received by the earth, the average
distance from the sun being 475,693,000 miles.

"And how about these satellites? Sometimes, I suppose, Jupiter has the
benefit of four moons all shining at once?" asked Servadac.

Of the satellites, Lieutenant Procope went on to say that one is rather
smaller than our own moon; that another moves round its primary at an
interval about equal to the moon's distance from ourselves; but that
they all revolve in considerably less time: the first takes only l day
18 hours 27 minutes; the second takes 3 days 13 hours 14 minutes; the
third, 7 days 3 hours 42 minutes; whilst the largest of all takes but 16
days 16 hours 32 minutes. The most remote revolves round the planet at a
distance of 1,192,820 miles.

"They have been enlisted into the service of science," said Procope. "It
is by their movements that the velocity of light has been calculated;
and they have been made available for the determination of terrestrial
longitudes."

"It must be a wonderful sight," said the captain.

"Yes," answered Procope. "I often think Jupiter is like a prodigious
clock with four hands."

"I only hope that we are not destined to make a fifth hand," answered
Servadac.

Such was the style of the conversation that was day by day reiterated
during the whole month of suspense. Whatever topic might be started, it
seemed soon to settle down upon the huge orb that was looming upon them
with such threatening aspect.

"The more remote that these planets are from the sun," said Procope,
"the more venerable and advanced in formation are they found to be.
Neptune, situated 2,746,271,000 miles from the sun, issued from the
solar nebulosity, thousands of millions of centuries back. Uranus,
revolving 1,753,851,000 miles from the center of the planetary system,
is of an age amounting to many hundred millions of centuries. Jupiter,
the colossal planet, gravitating at a distance of 475,693,000 miles,
may be reckoned as 70,000,000 centuries old. Mars has existed for
1,000,000,000 years at a distance of 139,212,000 miles. The earth,
91,430,000 miles from the sun, quitted his burning bosom 100,000,000
years ago. Venus, revolving now 66,131,000 miles away, may be assigned
the age of 50,000,000 years at least; and Mercury, nearest of all, and
youngest of all, has bee