Читать книгу Star-land: Being Talks With Young People About the Wonders of the Heavens онлайн

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But when we look at the sun we have no aids conveniently placed to help us in judging his distance. There are no intervening objects, and merely gazing at the sun helps us but little in obtaining any accurate knowledge. We must go to the astronomer and ask him to tell us how far he has found the sun to be, and then we must also beg from him some explanation of the method he has used in making his measurements.

It has been found that the sun is, on the average, about ninety-three millions of miles from the earth; but sometimes it is a little further and sometimes it is a little nearer. Let us first try to count 93,000,000. The easiest way will be to get the clock to do this for us; and here is a sum that I would suggest for you to work out. How long will the clock have to tick before it has made as many ticks as there are miles between the earth and the sun? Every minute the clock, of course, makes 60 ticks, and in 24 hours the total number will reach 86,400. By dividing this into 93,000,000 you will find that more than 1076 days, or nearly three years, will be required for the clock to perform the task.