. The children's book of stars . ing thismethod to the planets, for we know that the lightwhich comes from them to us is only reflected sun-light, and this, indeed, was proved by means of thespectroscope. But the stars shine by their ownlight, and this opened up a wide field for difficulty was, of course, to get the light of onestar separated from all the rest, because the lightof one star is very faint and feeble to cast a spectrumat all. Yet by infinite patience difficulties wereovercome. One star alone was allowed to throw itslight into the telescope ; the light passed througha
. The children's book of stars . ing thismethod to the planets, for we know that the lightwhich comes from them to us is only reflected sun-light, and this, indeed, was proved by means of thespectroscope. But the stars shine by their ownlight, and this opened up a wide field for difficulty was, of course, to get the light of onestar separated from all the rest, because the lightof one star is very faint and feeble to cast a spectrumat all. Yet by infinite patience difficulties wereovercome. One star alone was allowed to throw itslight into the telescope ; the light passed througha prism, and showed a faint band of many colours,with the expected little black lines cutting acrossit more or less thickly. Examinations have thusbeen made of hundreds of stars. In the course ofthem some substances as yet unknown to us onearth have been encountered, and in some starsone element—hydrogen—is much stronger than inothers; but, on the whole, speaking broadly, it hasbeen satisfactorily shown that the stars are made. THE SPECTRUM OF THE SUN AND SIRIUS. WHAT THE STARS ARE MADE OF 169 on the same principles as our own sun, so that thereasoning of astronomers which had argued themto be suns was proved. We have here in the picture the spectrum ofthe sun and the spectrum of Sirius. You cansee that the Hues which appear in the band ofHght belonging to Sirius are also in the band oflight belonging to the sun, together with manyothers. This means that the substances flamingout and sending us light from the far away star arealso giving out light from our own sun, and thatthe sun and Sirius both contain the same elementsin their compositions. This, indeed, seems enough for the spectroscopeto have accomplished ; it has interpreted for us themessage light brings from the stars, so that weknow beyond all possibility of mistake that theseglowing, twinkling points of light are brilliant sunsin a state of intense heat, and that in them areburning elements with which we ourselves a
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