"Yes, next door to the baby planets we come to the largest of all,
the giant planet Jupiter. If a tunnel were made through the center of
Jupiter, eleven globes as large as the earth, placed side by side, would
reach from one side to the other. You could make thirteen hundred globes
out of planet Jupiter as large as the earth. If the earth were a large
snowball, and a giant could roll thirteen hundred such snowballs into
one, he would have a ball to play with as large as planet Jupiter. If
it were made of the same material as the earth, it would be more than
three hundred times as heavy."
"It would take a very big giant to play with that snowball, wouldn't
it?" said Harry, smiling at the thought. "There would not be much room
in the sky for him to play in, would there?"
[Illustration: GIANT JUPITER AND THE EARTH.]
"Plenty of room," replied his sister, laughing; "room for millions and
millions of balls as large as Jupiter, and much, much larger."
"What a wonderful place the sky must be!" said Harry, in awe. "Now,
tell me some more about Jupiter. Didn't you tell me last week that he
is hidden away among blankets, and very, very hot?"
"That is right, Harry, but some day he will cool down, and the blankets
will change into beautiful oceans and seas and lakes. Then it will be
a world like ours, with trees and flowers, and perhaps people will live
there."
"The sun is so much further away from Jupiter than from the earth that
it gives it only one twenty-seventh as much light and heat. If you can
imagine the sun as a bright lamp in the sky, and someone turning down
the wick of the lamp till its light is only one twenty-seventh as bright
as it is now, you can imagine how dim the light and small the amount of
heat must be on Jupiter."
"How long does Jupiter take in going round the sun?" asked Harry.
"About twelve years," replied Mary; "and the day is only about ten hours
long, instead of twenty-four as here."
"What a short day!" said Harry, in surprise. "Then you could work only
five hours and sleep five hours. I believe I would sleep all day, and
all night, too. I must tell Nellie about that next time I see her."
"Why did not she come this morning, I wonder?" said Mary. "Perhaps she
has gone for a walk with her nurse."
"I'll tell her about my trip," said Harry generously, "when she comes
over here again. And now what else is there about Jupiter?"