Page:Popular Science Monthly Volume 1.djvu/30

20 Now, the question which has agitated astronomy during the past few years has been simply whether the glory of light seen around the sun is in reality a solar appendage, or may not be due wholly or in part to the illumination either of our own atmosphere or of some other matter (not necessarily atmospheric) lying much nearer to us than the sun does. If we consider the figure, we can see at once that if we have here a real solar appendage—that is, matter which exists all around the sun's globe—it is an appendage of the most amazing extent. The black disk which forms the centre of the figure is of course intended to represent the moon, whose diameter we know is about 2,200 miles, and if for a moment we suppose the corona and  surrounds the moon, we see that it must extend on one side to about 5,000 miles, and elsewhere to about 2,800 miles. But exactly behind the moon lies the sun, a little more than concealed by the moon; and the sun's diameter is about 850,000 miles. So that, if the corona is something which surrounds the sun, it extends, as the picture shows, to at least 2,000,000 miles on one side, and elsewhere to about 1,200,000 miles. Neglecting the dark rifts for the moment, and regarding the whole corona as shaped like a globe, and having a diameter four times as great as the sun's, we should have to regard its volume as exceeding his not four times, nor sixteen times, but sixty-four times. And when we are reminded that the sun's own volume exceeds that of this earth on which we live some 1,200,000 times, we see what a stupendous conclusion we must arrive at, if we regard the corona as a solar appendage. Of course, we need not imagine that the corona has a continuous substance completely filling a space some 77,000,000 times larger than the earth. It may be made up of multitudes of minute bodies, with vacant spaces between. But the conclusion remains that a region of space, exceeding our earth's volume so many millions of times, is thus occupied by matter of some sort.

Nor is the conclusion rendered a whit less surprising if we take the dark rifts into account. Nay, we obtain an enhanced idea of the wonderful nature of the corona, regarded as a solar appendage, when we consider that it possesses so remarkable a structure that, as seen from our distant stand-point, it shows well-defined gaps or rifts. For unquestionably it is not to be regarded as something flat or plane shaped, like its picture, or a decoration (which in appearance it often strikingly resembles). It must extend on all sides from the sun (if it is indeed a solar appendage), and not merely from the sides of the disk he turns toward us at the time of an eclipse; and it can easily be seen that its shape, in length and breadth and thickness, must be strange, to account for such rifts as are shown in the figure. If we take an orange to represent the sun, and, boring holes all over it, stick spills in these holes to represent the region occupied by the corona, we shall find that, in order that our spillikined orange may exhibit a rifted corona in whatever position it is placed, we must either leave several