“Of course it moves,” said Philip.  “I always see it in the morning when I am in the garden.  It rises first above the bushes, then over the trees and houses; by evening it has traveled across the sky, when it sinks below the houses and trees, out of sight on the other side of the town.”

“Now that is quite a mistake,” said Frank, “You think that the sun is traveling all that way along the sky, whereas it is really we—­we on this big ball of earth—­who are moving.  We are whirling around on the outer surface, rushing on at the rate—­let me think—­at the rate of more than one thousand miles a minute!”

“Frank, what do you mean?” cried Philip.

“I mean that the earth is moving many times faster than a ball moves when shot from the mouth of a cannon!”

“Do you expect me to believe that, Frank!  I can hardly believe that this big, solid earth moves at all; but to think of it with all the cities, towns, and people whirling round and round faster than a ball from the mouth of a cannon, while we never feel that it stirs one inch,—­this is much harder to believe than all that the fairies have ever told us.”

“Yes, but it is quite true for all that,” replied Frank.

“I have learned much about the motions of the planets, and viewed the stars one night through a telescope.  As I looked through this instrument, the stars appeared to me much larger than ever before.  The earth is a planet, and there are besides our earth seven large planets and many small ones, which also whirl around the sun.  Some of these planets are larger than our world.  Some of them also move much faster.

“The sun is in the middle with the planets moving around him.  The one nearest to the sun is Mercury.”

“It must be hot there!” cried Philip.

“I dare say that if we were in Mercury we should be scorched to ashes; but if creatures live on that planet, God has given them a different nature from ours, so that they may enjoy what would be dreadful to us.

“The next planet to Mercury is Venus.  Venus is sometimes seen shining so bright after sunset; then she is called the evening star.  Some of the time, a little before sunrise, she may be seen in the east; she is then called the morning star.

“Venus can never be an evening star and a morning star at the same time of the year.  If you are watching her this evening before or after sundown, there is no use getting up early to-morrow to look for her again.  For several weeks Venus remains an evening star, then gradually disappears.  Two months later you may see her in the east—­a bright morning star.

“Our earth is the third planet, and Mars is the fourth from the sun.  Now let us make a drawing of what we have been talking about.

“First open the compasses one inch; describe a circle, and make a dot on its circumference, naming it Mercury.  Write on this circle eighty-eight days; this shows the time it takes Mercury to travel around the sun.  Make another circle three and one-half inches in diameter and make a dot on it.  This represents Venus.  It takes Venus two hundred twenty-five days to journey around the sun.