orms and currents,
especially in the equatorial regions. Jupiter is thought to be self
luminous, at least in parts, and is, perchance, a cooling star, not yet
entirely crusted over.
"Four or five numbered satellites, about the size of our moon and
upwards, are circulating round him in orbits from 2,000 to 1,000,000
miles distant in periods ranging from 11 hours to 16 days 18 hours.
"Saturn, the 'ringed planet,' who appears as a dull red star of the
first magnitude, is the most interesting of all the planets. He is 884
million miles from the sun; his period of revolution is 291/2 years, and
he turns on his axis in 10 hours 14 minutes. His diameter is 75,000
miles, but his mass is only 94 times that of the earth, for he is
lighter than pinewood. His atmosphere is marked with spots and belts,
and on the whole his condition is like that of Jupiter.
"Two flat rings or hoops, divided by a dark space, encircle his ball in
the plane of his equator. The inner ring is over 18,000 miles from the
ball, and nearly 17,000 miles broad. The gap between is 1,750 miles
wide, and the outer ring is over 10,000 miles broad. The rings are
banded, bright or dark, and vary in thickness from 40 to 250 miles. They
consist of innumerable small satellites and meteoric stones, travelling
round the ball in rather more than ten hours, and are brightest in
their densest parts. Of course they form a magnificent object in the
night sky of the planet, and it may be that our own zodiacal light is
the last vestige of a similar ring, and not an extension of the solar
corona.
"Saturn has eight moons outside his rings, the nearest, Mimas, being
115,000, and the farthest, Japetus, 220,400 miles from his ball. With
the exception of Japetus, they revolve round him in the plane of his
rings, and when these are seen edgewise, appear to run along it like
beads on a string.
"Uranus, the next planet visible, is a pale star of the sixth magnitude,
1,770 million miles from the sun, and completes his round in 84 years.
His axis, differing from those of the foregoing planets, lies almost in
the plane of his orbit, but we cannot speak as to his axial rotation. He
is 31,000 miles in diameter, and somewhat heavier, bulk for bulk, than
water. Four satellites revolve round him, the nearest, Ariel, being
103,500, and the farthest, Oberon, 347,500 miles distant. Unlike the
orbits of the foregoing satellites, which are nearly in the same plane
as the orbits of their p
|