cold it would be; far colder than the most wintry weather ever known, because in the bitterest night some warmth comes out of the earth, where it has been stored from the sunlight which fell during the day.  But if we never received any warmth at all, no water would ever rise up into the sky, no rain ever fall, no rivers flow, and consequently no plants could grow and no animals live.  All water would be in the form of snow and ice, and the earth would be one great frozen mass with nothing moving upon it.

So you see it becomes very interesting for us to learn what the sun is, and how he sends us his beams.  How far away from us do you think he is?  On a fine summer’s day when we can see him clearly, it looks as if we had only to get into a balloon and reach him as he sits in the sky, and yet we know roughly that he is more than ninety-one millions of miles distant from our earth.

These figures are so enormous that you cannot really grasp them.  But imagine yourself in an express train, travelling at the tremendous rate of sixty miles an hour and never stopping.  At that rate, if you wished to arrive at the sun today you would have been obliged to start 171 years ago.  That is, you must have set off in the early part of the reign of Queen Anne, and you must have gone on, never, never resting, through the reigns of George I, George ii, and the long reign of George III, then through those of George IV, William IV, and Victoria, whirling on day and night at express speed, and at last, today, you would have reached the sun!

And when you arrived there, how large do you think you would find him to be?  Anaxagoras, a learned Greek, was laughed at by all his fellow Greeks because he said that the sun was as large as the Peloponne-sus, that is about the size of Middlesex.  How astonished they would have been if they could have known that not only is he bigger than the whole of Greece, but more than a million times bigger than the whole world!

Our world itself is a very large place, so large that our own country looks only like a tiny speck upon it, and an express train would take nearly a month to travel round it.  Yet even our whole globe is nothing in size compared to the sun, for it only measures 8000 miles across, while the sun measures more the 852,000.

Imagine for a moment that you could cut the sun and the earth each in half as you would cut an apple; then if you were to lay the flat side of the half-earth on the flat side of the half sun it would take 106 such earths to stretch across the face of the sun.  One of these 106 round spots on the diagram represents the size which our earth would look if placed on the sun; and they are so tiny compared to him that they look only like a string of minute beads stretched across his face.  Only think, then, how many of these minute dots would be required to fill the whole of the inside of Fig. 4, if it were a globe.