"'Oh, yes!' said one of the visitors. 'I saw them going round in the telescope.'
"But it was the twinkling that made the stars appear to dance around each other. In reality, he would have had to remain with his eye at the telescope more than a hundred years before he could have seen the stars go completely around each other."
NUMBER OF THE STARS.
"I wonder how many stars there are in the sky, sister," said Harry. "Do you think we could count them?"
"I read somewhere," replied his sister, "that the stars are as plentiful as the sands on the seashore. Still, in the whole sky, the number bright enough to be seen without a telescope is only from six to seven thousand in a clear, moonless sky. With an opera glass you can bring the number up to one hundred thousand. A small telescope can show about three hundred thousand, while with a telescope such as the one at the Lick Observatory the number would be nearly one hundred million. But it is possible to photograph the stars, and millions of stars have had their pictures taken. Probably we would never have known anything about them but the camera caught them, and now they are being named and labeled, so that they cannot escape us again. In fact, some of the stars are so far away that if we had not captured them in this way they would have remained hidden to us forever."
"What do you mean, sister?" said Harry, his eyes filled with surprise.
"I mean, dear, that some stars are so far away that their light has not yet reached us. Don't you remember what I told you about Jupiter's moons: that they are so far away that light takes about half an hour in coming from them to the earth. Well, the stars are hundreds of times as far away as Jupiter's moons. So far away are they that even from the nearest—a star seen in the southern hemisphere—light takes four years and four months in reaching us, although light travels more than 186,000 miles a second."
DISTANCE OF THE STARS.
"Look at the Pole Star some night, and you will not see it as it is now, but as it was more than sixty-two years ago. All this time its light has been on its way to Planet Earth. If a planet travels around the Pole Star, or Polaris, as it is sometimes called, and an astronomer on that planet looked at the earth he would not see it as it is now, but as it was more than sixty-two years ago. There are other stars so far away that light takes hundreds of years in coming here. Perhaps they faded out long ago, but the message is still on its way. It does seem strange to think of people who may be living on distant worlds in space, watching our little world, but we need not fear. The earth is so small that it could not be seen at all, even from the nearest star. At that distance Giant Sun would not look quite as bright as Sirius does to us, and giant Planet Jupiter would only appear as a faint speck of light near the sun."
"How far away everything seems to be!" said Harry. "Yet you said just now that we could tell what the stars are made of. How can we do that?"