The Children's Book of Stars

covering all the sky from the zenith, the highest point above your head, down to the horizon. It seems as if so

it bright with a pervading and diffused light. As this is not so, we judge that the universe is not unending, though, with all our inventions, we may never be able to probe to the end of it. We need not, indeed, cry for infinity, for the distances of the fixed stars from us are so immeasurable that to atoms like ourselves they may well seem unlimited. Our solar system is set by itself, like a little island in space, and far, far away on all sides are other great light-giving suns resembling our own more or less, but dwindled to the size of tiny stars, by reason of the great void of space lying between us and them. Our sun is, indeed, just a star, and by no means large compared with the average of the stars either. But, then, he is our own; he is comparatively near to us, and so to us he appears magnificent and uni

we to a yellow sun that we never think of the possibility of there being one of another colour. What would you say then to a ruby sun, or a blue one; or to two suns of different colours, perhaps red and green, circling round each other; o

he stars intimately, and even now they are baffled by indescribable difficulties. One of these is our inability to tell the distance of a thing by merely looking at it unless we also know its size. On earth we are used to seeing things appear smaller the further they are from us, and by long habit can generally tell the real size; b

urthest away of all; but research has shown that this is not correct. Some of the brightest stars may be comparatively near, and some of the smallest may be near also. The size is no test of distance. So far as we have been able to discover, the star

his, but if you think for a moment you will remember that when you are in a railway-carriage everything in that carriage is really travelling along with it, though it does not appear to move. And the whole solar system may be looked at as if it were one block in movement. As in a carriage, the different bodies in it continue their own movements all the time, while sharing in the common movement. You can get up and change your seat in the train, and when you sit down again you have not only moved that little way of which you are conscious, but a great way of which you are not conscious unless you look out of the window. Now in the case of the earth's own motion we found it necessary to look for something which does not share in that motion for purposes of comparison, and we found that something in the sun, who shows us very clearly we are turning on our axis. But in the case of the motion of the solar system the sun is moving himself, so we have to look beyond him again and turn to the stars for confirmation. Then we find that the stars have

aken as a convenient measure by astronomers for sounding the depths of space. Measured in this way light takes four years and four months to reach us from the nearest star we know of, and there are others so much more distant that hundreds-nay, thousands-of years would have to be used to convey it. Light which has been travelling along with a velocity quite beyond thought, silently, unresting, from the time when the Britons lived and ran half naked on this island of ours, has only reached us now, and there is no limit to the time we may go back in our imaginings. We see the stars, not as they are, but as they were. If some gigantic conflagration had happened a hundred years ago in one of them situated a hundred light-years away from us, only now would that messenger, swifter than any messenger

and the angles at each end of it, you can form the rest of the triangle; that is to say, you can tell the length of the other two sides. In this instance the base line, as it is called-that is to say the line lying between the two eyes-can easily be measured, and the angles at each end can be found by an instrument called a sextant, so that by simple calculation anyone could find out what distance the finger was from the eye. Now, some ingenious man decided to apply this method to the stars. He knew that it is only objects quite near to us that will appear to shift with so small a base line as that between the eyes, and that the further away anything is the longer must the base line be before it makes any difference. But this clever man thought that if he could only get a base line long enough he could easily compute the distance of the stars from the amount that they appeared to shift against their background. He knew that the longest base line he could get on earth would be about eight thousand miles, as that is the diameter of the earth from one side to the other; so he carefully observed a star from one end of this immense base line and then from the other, quite confid

sier to understand when we put it the other way round and say that the hair's-breadth is what the who

hem, astronomers have invented a system. To only the very brightest are proper names attached; others are noted according to the degree of their brightness, and called after the letters of the Greek alphabet: alpha, beta, gamma, delta, etc. Our own word 'alphabet' comes, you know, from the first