The Sun.—That spots upon the sun may be seen with no greater optical aid than that of an opera-glass is perhaps well known to many of my readers, for during the past ten years public attention has been drawn to sun-spots in an especial manner, on account of their supposed connection with meteorology, and in that time there have been many spots upon the solar disk which could not only be seen with an opera-glass, but even with the unassisted eye. At present (1888) we are near a minimum period of sun-spots, and the number to be seen even with a telescope is comparatively very small, yet only a few days before this page was written there was a spot on the sun large enough to be conspicuous with the aid of a field-glass. During the time of a spot-maximum the sun is occasionally a wonderful object, no matter how small the power of the instrument used in viewing it may be. Strings of spots of every variety of shape sometimes extend completely across the disk. Our illustration shows the appearance of the sun, as drawn by the author on the 1st of September, 1883. Every one of the spots and spot-groups there represented could be seen with a good field-glass, and nearly all of them with an opera-glass.
The Sun, September 1, 1883.
As in all such cases, our interest in the phenomena increases in proportion to our understanding of their significance and their true scale of magnitude. In glancing from side to side of the sun's disk, the eye ranges over a distance of more than 860,000 miles—not a mere ideal distance, or an expanse of empty space, but a distance filled by an actual and, so to speak, tangible body, whose diameter is of that stupendous magnitude. One sees at a glance, then, the enormous scale on which these spots are formed. The earth placed beside them would be but a speck, and yet they are mere pits in the surface of the sun, filled perhaps with partially cooled metallic vapors, which have been cast up from the interior, and are settling back again. It is worth anybody's while to get a glimpse at a sun-spot if he can, for, although he may see it merely as a black dot on the shining disk, yet it represents the play of physical forces whose might and power are there exercised on a scale really beyond human comprehension. The imagination of Milton or Dante would have beheld the mouth of hell yawning in a sun-spot.
In order to view the sun it is, of course, necessary to contrive some protection for the eyes. This may be constructed by taking two strips of glass four or five inches long and an inch wide, and smoking one of them until you can without discomfort look at the sun through it. Then place the two strips together, with the smoked surface inside—taking care to separate them slightly by pieces of cardboard placed between the ends—and fasten the edges together with strips of paper gummed on. Then, by means of a rubber band, fasten the dark glass thus prepared over the eye-end of your opera-glass in such a way that both of the lenses are completely covered by it. It will require a little practice to enable you to get the sun into the field of view and keep it there, and for this purpose you should assume a posture—sitting, if possible—which will enable you to hold the glass very steady. Then point the glass nearly in the direction of the sun, and move it slowly about until the disk comes in sight. It is best to carefully focus your instrument on some distant object before trying to look at the sun with it.
As there is some danger of the shade-glass being cracked by the heat, especially if the object-glasses of the instrument are pretty large, it would be well to get the strips of glass for the shade large enough to cover the object-end of the instrument instead of the eye-end. At a little expense an optician will furnish you with strips of glass of complementary tints, which, when fastened together, give a very pleasing view of the sun without discoloring the disk. Dark red with dark blue or green answer very well; but the color must be very deep. The same arrangement, of course, will serve for viewing an eclipse of the sun.
A word, finally, about the messenger which brings to us all the knowledge we possess of the contents and marvels of space—light. Without the all-pervading luminiferous ether, narrow indeed would be our acquaintance with the physical creation. This is a sympathetic bond by which we may conceive that intelligent creatures throughout the universe are united. Light tells us of the existence of suns and systems so remote that the mind shrinks from the attempt to conceive their distance; and light bears back again to them a similar message in the feeble glimmering of our own sun. And can any one believe that there are no eyes out yonder to receive, and no intelligence to interpret that message?
Sir Humphry Davy has beautifully expressed a similar thought in one of his philosophical romances:
In Jupiter you would see creatures similar to those in Saturn, but with different powers of locomotion; in Mars and Venus you would find races of created forms more analogous to those belonging to the Earth; but in every part of the planetary system you would find one character peculiar to all intelligent natures, a sense of receiving impressions from light by various organs of vision, and toward this result you can not but perceive that all the arrangements and motions of the planetary bodies, their satellites and atmospheres, are subservient. The spiritual natures, therefore, that pass from system to system in progression toward power and knowledge preserve at least this one invariable character, and their intellectual life may be said to depend more or less upon the influence of light.[G]
Light is a result, and an expression, of the energy of cosmical life. The universe lives while light exists. But when the throbbing energies of all the suns are exhausted, and space is filled with universal gloom, the light of intelligence must vanish too.