Part 13

STORY OF JUPITER.

"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?"

"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?"

JUPITER AS SEEN THROUGH A TELESCOPE.

"If you look at it through a large telescope you will see that it is beautifully colored, as if Uncle Robert had taken his paint-box, and dipped his brush into browns and reds, and tinted the cloud-belts around Jupiter here and there with touches of yellow and orange, olive-green and purple. Only an artist could get such beautiful effects. If we could journey to one of the little moons of Jupiter----"

"Has Jupiter moons also?" asked Harry, delighted at the thought.

"Five of them," said Mary; "and I shall tell you about them later. Supposing we could journey to one of these little moons, what a glorious sight Jupiter would be! From the nearest moon it would look thousands of times larger than our moon. The colors we see only faintly through our telescopes would present a magnificent sight when seen at close range, while constant changes would be taking place, as varied as the changes in the clouds flitting across a summer sky. Great cloud-masses drift hither and thither with enormous speed, driven by winds of hurricane force. By watching the changes that take place in the clouds, we know there must be winds blowing at the rate of nearly two hundred miles per hour. Do you remember the cyclone Uncle Robert told us about, when several houses were blown down and trees uprooted?"

"Yes, indeed, I do," replied Harry, "and his poor little dog Fido was nearly killed by a falling chimney."

"Poor little Fido would not have much chance on Jupiter. The storms there are ever so much worse than here. The strongest buildings would be blown down in a few moments; sturdy oaks would be uprooted and blown about by the wind like straws."

"Do the storms last very long?" asked Harry.

"They last six and seven weeks at a time," replied Mary, "so that Jupiter would scarcely be a comfortable world to live on yet. Besides, it is still in the fiery stage."

"Won't you tell me some more about the little moons of Jupiter?" asked Harry.

THE MOONS OF JUPITER.

"They are not so little, after all, brother, except the first one, which is only one hundred miles wide. It is such a shy little moon that it keeps hiding behind Jupiter, or gets so close to him that it is lost in the glare of light from the giant planet. We had no idea it was there at all until an American astronomer, Professor Barnard, caught sight of it one evening. It was playing hide-and-seek as usual, but Professor Barnard, with his keen eyes, spied the little speck of light. It is now known as the fifth moon of Jupiter. It was only discovered in 1892, and just think, that for the hundreds and hundreds of years it has been there, yet no one had seen it. The French people were so delighted because Professor Barnard caught sight of the little truant that they gave him a beautiful gold medal."

"Won't you show the little moon to me sometime?" said Harry. "I should like to see it so much."

"You can only see it through a very large telescope; but I can show you the other four moons if Uncle Robert will lend us his telescope."

"Here he comes," said Harry, in great glee, as he saw Uncle Robert crossing the meadow. "Won't you bring over your telescope this evening?" said Harry pleadingly, as he told him what Mary had just said.

"Certainly, my little man," his uncle replied; "but we can only see three of the moons this evening as one of them is eclipsed."

"What's that?" said Harry, in surprise at the strange word.