What Makes the Stars Twinkle?
I might tell you, just to show how clever I am, that stars do not twinkle at all, and leave you with that for an answer. But since they really do seem to twinkle, and that is what causes your question, I will tell you. As we have already learned in our talks about the stars and the sky in general, the stars are suns which are constantly throwing off light, just as our sun gives us light, and when this light strikes the air which surrounds the earth it meets many objects—little particles of dust and other things always floating about in it. The light comes to us in the form of rays from the stars and some of these rays strike particles of various kinds in the air and are thus interfered with. If you are looking at a lighted window some distance away and there are a lot of boys and girls or men and women running past the window, one after the other, rapidly, it will make the light in the window appear to twinkle. The twinkling is due to the interference which the rays of light encounter while traveling toward the eye.