Page:Popular Science Monthly Volume 58.djvu/436

428 delicate photographs. It is certain that the background of the sky itself is by no means black. The only question is, whether the light from this background is mostly reflected by our atmosphere from the stars. It may seem questionable whether such is the case, because the fraction reflected in a clear atmosphere is not supposed to exceed one-tenth the total amount of light of the stars themselves. On the other hand, the seemingly blue color of the sky might seem to militate against this view, since the average color of all the stars is white rather than blue. The subject is an extremely interesting one and requires further investigation before a definitive conclusion can be reached.