"How far away is the sun?" asked Harry.
"It is so far away that it would take more than a hundred years to travel the distance by the fastest railroad train."
"Is it more than a thousand miles?"
"Yes, it is more than a million miles."
"Suppose there were a road all the way to the sun. How long would it take me to walk there?"
"Let me see," said sister Mary, taking out her notebook. "If you should walk four miles an hour and ten hours a day, you would be more than six thousand years old before you could finish your journey."
"But suppose," asked Harry, his eyes bright with wonder, "some one fired a big cannon at the sun. How long would it take the cannon ball to get there?"
Mary looked in her notebook again. "If a cannon ball could be shot to the sun, it would take nine years to reach it. Now what else do you want to know about the sun, little brother?"
"I should like to know how large it is. Does any one know? Is it as large as the earth?"