Yet, even in our time, it is not possible to assert confidently that such fears are idle. During the solar outburst witnessed by Carrington and Hodgson in September 1859, it is supposed that the sun swallowed a large meteoric mass; and, as great cornets are probably followed by many such masses, it seems reasonable to infer that if such a comet fell upon the sun, his surface being pelted with such exceptionally large masses, stoned with these mighty meteoric balls, would glow all over (or nearly so) as brightly as a small spot of that surface glowed upon that occasion. Now that portion was so bright that Carrington thought 'that by some chance a ray of light had penetrated a hole in the screen attached to the object-glass by which the general image is thrown in shade, for the brilliancy was fully equal to that of direct sunlight.' Manifestly, if the whole surface of the sun, or any large portion of the surface, were caused to glow with that exceeding brilliancy, surpassing ordinary sunlight in the same degree that ordinary sunlight surpassed the shaded solar image in Carrington's observations, the result would be disastrous in the extreme for the inhabitants of that half of the earth which chanced to be in sunlight at the time; and if (as could scarcely fail to happen) the duration of that abnormal splendour were more than half a day, then the whole earth would probably be depopulated by the intense heat. The danger, as I have said, is slight--partly because there is small chance of a collision between the sun and a comet, partly because we have no certain reasons for assuming that a collision would be followed by the heating of the sun for a while to a very high temperature. Looking around at the suns which people space, and considering their history, so far as it has been made known to us, for the last two thousand years, we find small occasion for fear. Those suns seem to have been for the most part safe from any sudden or rapid accessions of heat; and if they travel thus safely in their mighty journeys through space, we may well believe that our sun also is safe. Nevertheless, there _have_ been catastrophes here and there. Now one sun and now another has blazed out with a hundred times its usual lustre, gradually losing its new fires and returning to its customary brightness; but after what destruction among those peopling its system of worlds who shall say? Spectroscopic analysis, that powerful help to the modern astronomical inquirer, has shown in one of these cases that just such changes had taken place as we might fairly expect would follow if a mighty comet fell into the sun. If this interpretation be correct, then we are not wholly safe. Any day might bring us news of a comet sailing full upon our sun from out the depths of space. Then astronomers would perhaps have the opportunity of ascertaining the harmlessness of a collision between the ruler of our system and one of the long-tailed visitors from the celestial spaces.