Page:Popular Astronomy - Airy - 1881.djvu/87

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LECTURE II.
73

meridian. On the first of April, at eleven o'clock at night, you again look out, and you see what is the state of things. The constellation Leo then has almost passed the meridian, except the bright star B (Beta) Leonis. On the first of May, at eleven o'clock at night, you again look out. You then observe that Leo and the whole set of stars are travelling away to the west; and then we have the bright star Spica, in the constellation Virgo, on the meridian: and we have the great red star Arcturus approaching the meridian. In the following month, on the first of June, at the same hour of the night, we again look out. We find that Spica has gone away to the west; that Arcturus has passed the meridian; and that other less conspicuous stars are on the meridian. In the same manner, if we go through the other months of the year; if, at eleven o'clock at night, on the first day of every month, we watch the appearances of the stars on the meridian, and compare them with those of the preceding month, we find that, from one month to another, they all travel on in the same direction towards the west.

Now, what is the inference? Is there any peculiarity in the motions of the stars? No, it is the motion of the sun. Our hour of eleven at night is referred by habit to the motion of the sun; and thus, when we speak of eleven o'clock at night, we mean that the sun is in a certain position; and, therefore, that the stars have moved in a direction from east to west, with respect to the sun.

But this may be interpreted another way. Regarding the stars as fixed objects, we get this: the sun travels round in the direction from west to east among the stars. Besides this, we have found that he travels in such a manner, that he goes nearer the