The very act of the solar whirlwind’s motion seemed to pass before my eyes in some of these sketches; for while drawing them as rapidly as possible, a new hole would be formed where there was none before, as if by a gigantic invisible auger boring downward.
FIG. 27.—PHOTOGRAPH OF EDGE OF SUN. (BY PERMISSION OF WARREN DE LA RUE, LONDON.)
M. Faye, the distinguished French astronomer, believes that, owing to the fact that different zones of the sun rotate faster than others, whirlwinds analogous to our terrestrial cyclones, but on a vaster scale, are set in motion, and suck down the cooled vapors of the solar surface into its interior, to be heated and returned again, thus establishing a circulation which keeps the surface from cooling down. He points out that we should not conclude that these whirlwinds are not acting everywhere, merely because our bird’s-eye view does not always show them. We see that the spinning action of a whirlpool in water becomes more marked as we go below the surface, which is comparatively undisturbed, and we often see one whirl break up into several minor ones, but all sucking downward and never upward. According to M. Faye, something very like this takes place on the sun, and in [Fig. 25] he gives this section to show what he believes to occur in the case of a spot which has “segmented,” or divided into two, like the one whose (imaginary) section is shown above it. This theory is to be considered in connection with such drawings as we have just shown, which are themselves, however, no way dependent on theory, but transcripts from Nature.
I do not here either espouse or oppose the “cyclonic” theory, but it is hardly possible for any one who has been an eyewitness of such things to refuse to regard some such disturbance as a real and efficient cause in such instances as this.
[Fig. 26], on nearly the same scale as the last, shows a spot which was seen on Oct. 13, 1876. It looked at first, in the telescope, like two spots without any connection; then, as vision improved and higher powers were employed, the two were seen to have a subtle bond of union, and each to be filled with the most curious foliage-forms, which I could only indicate in the few moments that the good definition lasted. The reader may be sure, I think, that there is no exaggeration of the curious shapes of the original; for I have been so anxious to avoid the overstatement of curvature that the error is more likely to be in the opposite direction.
We must conclude that the question as to the cyclonic hypothesis cannot yet be decided, though the probabilities from telescopic evidence at present seem to me on the whole in favor of M. Faye’s remarkable theory, which has the great additional attraction to the student that it unites and explains numerous other quite disconnected facts.
Turning now to the other solar features, let us once more consider the sun as a whole. [Fig. 27] is a photograph taken from a part of the sun near its edge. We notice on it, what we see on every careful delineation of the sun, that its general surface is not uniformly bright, but that it grows darker as we approach the edge, where it is marked by whiter mottlings called faculæ, “something in the sun brighter than the sun itself,” and looking in the enlarged view which we present of one of them ([Fig. 28]), as if the surface of partly cooled metal in a caldron had been broken into fissures showing the brighter glow beneath. These “faculæ,” however, are really above the solar surface, not below it, and what we wish to direct particular attention to is that darkening toward the edge which makes them visible.
FIG. 28.—FACULA. (FROM A DRAWING BY CHACORNAC.)