Lower figure.—Sudden electric discharge through the atmosphere, from left to right.
Around the earth and other planets gravity attracts the aqueous vapors in increased density, the same as around the sun; but the electric currents passing between the planets and the sun decompose this aqueous vapor into its constituent gases, hydrogen and oxygen. The oxygen is deposited within the positive electrospheres of the planetary bodies, where it mingles with nitrogen to form our atmosphere and those of the other planets. In this float the aqueous vapors condensed from space, which are lighter than air. (See Tyndall, “The Forms of Water:” “It also sends up a quantity of aqueous vapor which, being far lighter than air, helps the latter to rise.”) These aqueous vapors, condensed into clouds and precipitated upon the earth, form our oceans and their affluents. The hydrogen gas disengaged upon the sun’s surface forms a similar envelope, which is penetrated by the planetary electric currents, and is thus highly heated and rendered incandescent; the glowing hydrogen transmits its heat to the sun’s mass within, which is thus raised to, and permanently maintained in, a liquid or densely gaseous state, its metallic constituents being volatilized in part, and these metallic vapors mingle with the lower strata of hydrogen to form the sun’s photosphere, while, above, the glowing hydrogen grows more pure, and finally, at a distance of hundreds of thousands of miles, is merged into the corona, which is composed, in part at least, of cosmical dust rotating around and repelled by the sun, and which shines partly by reflected light, partly by that of the relatively cooler hydrogen, and partly, perhaps, by electrification of its constituents by the powerful currents passing through it. Each of the planetary bodies, large or small, takes its proportionate part in the generation and transmission of electricity, according to its volume, mass, and motion. As an adjunct to this electrical sequence we have learned that any interruption of such currents between the generator and the receiver will cause the generating apparatus to glow with diffused electrical light, as is the case with the Wimshurst machine already described. When such connection is removed, it is said, “the whole apparatus bristles with electricity, and if viewed in the dark presents a most beautiful appearance, being literally bathed with luminous brush discharges.” Such a phenomenon recalls at once the aurora borealis; and when we find this as a sequence of the electrical storm of the first of September, 1859, before described (“at night great auroras were seen in both hemispheres”), and connect with this the persistence of electricity upon insulated surfaces (see “Electricity in the Service of Man,” page 53: “Glass being a bad conductor, the electricity does not spread all over the plate, but remains where it is produced”), we shall inevitably conclude that there was some partial interruption in the current flowing from the earth to the sun at that moment; and if we recall that at that very instant “suddenly a bright light was seen by each observer to break out on the sun’s surface and to travel across a part of the solar disk,” we shall learn that the processes connected with the production of such a bright light will interrupt in part the terrestrial current. We can readily understand that if this bright light exceeded in electrical intensity that due to the earth’s current, it might temporarily reverse the polarity of the afferent current or retard its flow, like the so-called “backwater” of a mill. It would be like attempting to discharge steam at sixty pounds’ pressure into a vessel filled with other steam at sixty-one pounds. Whence, then, came this bright light? Perhaps from the conjoint action of some other planet, perhaps from sudden chemical disassociation beneath the surface, perhaps by the abnormal piling up of depths of transparent glowing hydrogen or other local disturbance.
Position of planets with reference to the generation of sun-spots.—S, the sun; S′, axis of sun’s rotation inclined 7° to plane of planetary rotation; A B, C, D, maximum intensity of planetary action; A′, B′, C′, D′, minimum intensity of same.
And this leads to the consideration of the uniformity of solar action. The planetary electrospheres will be constant in their operation if the constitution of surrounding space remains uniform; but we shall find reason to believe that there are currents in the ocean of space, as there are currents in our own seas, and electrical generation will necessarily vary when such currents are encountered. The sun itself in such case, however, will become an automatic regulator, for his density being but one-fourth that of the earth, and the spectroscope having shown his chemical composition to a large extent, we know that his mass must be either liquid or vaporous, and perhaps in part both. Such masses readily respond to variations of temperature, expanding as it rises and contracting as it falls. Hence, if a portion of space were reached where the action of the planetary electrospheres was increased by relative increase of temperature in some interstellar “Gulf Stream,” the sun’s volume would expand and compensation be at once established, while, conversely, with diminution of such planetary action, the solar volume would contract and an increased supply from his reserve store be given out thereby. In this way the condensation relied upon to give us heat for seven or seventeen million years becomes a compensating mechanism, self-operative through the most distant cycles of time. We shall also find in such electric currents an explanation of sun-spots. It is not meant that a full knowledge can be obtained of their minute constitution, nor is it necessary; but the equatorial belt of six degrees, nearly free from sun-spots, we can readily understand to be caused—since sun-spots are depressions in the photosphere down to the deeper and denser cloud strata beneath—by the equatorial piling up of the sun’s atmosphere by its rotation. Any point on the sun’s equator travels at four times the rotational velocity of one on the earth’s equator, but the sun’s attraction of gravity is twenty-seven and one-tenth times that of the earth, so that the piling up of an atmosphere of hydrogen would be considerable, and such depressions would not ordinarily exist there. Similarly, near the sun’s poles we should find a gradual darkening, as is the case; but from five degrees to thirty degrees latitude, the sun, in its rotation, by reason of the inclination of its axis, passes at every point directly beneath the planets, or within their area of control, and here we find the solar spots in their greatest number, size, and intensity. These sun-spots cross the face of the sun in about fifteen days, and vary in development from year to year, having a cycle of 11.11 years from maximum to maximum. They also have a long cycle of about fifty-six years. (See article “The Sun,” in Appleton’s Cyclopædia.) “Wolf, in 1859, presented a formula by which the frequency of spots is connected with the motions of the four bodies, Venus, the earth, Jupiter, and Saturn. Professor Loomis, of Yale College, has since advocated a theory (suggested by the present writer [Proctor] in 1865, in ‘Saturn and his System,’ page 168, note) that the long cycle of fifty-six years is related to the successive conjunctions of Saturn and Jupiter. But the association is as yet very far from being demonstrated, to say the least.” Should such fact be established, an explanation for it will be found in the direct impact of the condensed electric currents from several planets approaching conjunction, and raising a portion of the sun’s atmosphere suddenly to a higher temperature and volatilizing an abnormal proportion of the semi-vaporous metallic core beneath. This would form an upburst piling the intensely heated faculæ up on the sides and revealing the relatively darker masses of cloud beneath, the cooler supernatant hydrogen pouring in from the upper layers to fill the returning void. This is precisely what is seen in such spots and their surrounding disturbances. In the article “The Sun,” above quoted, we read, “Mr. Huggins has found that several of the absorption bands belonging to the solar spectrum are wider in the spectrum of a spot, a circumstance indicative of increased absorption so far as the vapors corresponding to such lines are concerned …. Near the great spots or groups of spots there are often seen streaks more luminous than the neighboring surface, called faculæ. They are oftenest seen towards the borders of the disk.” This writer also describes “luminous bridges across spots which sink into the vortex and are replaced by others of the numberless cloud-like forms from one hundred to one thousand miles in diameter, the brilliancy of which so greatly exceeds that of the intervening spaces that they must be recognized as the principal radiators of the solar light and heat.” The apparent retardation of the spots most distant from the sun’s equator may also be partially, at least, explained by planetary currents of electricity, as the equatorial atmosphere is deeper and more likely to carry forward such vortices when formed, while the planets act more directly on the sun’s mass beneath their direct influence.
Let us consider this retardation of sun-spots somewhat more in detail. Take, for example, the case of a large planet at such orbital position that its direct line of electrical impact will penetrate the photosphere at (say) seven degrees north solar latitude, which is about fifty-two thousand miles from his equator. During its annual revolution this planet will traverse, with its line of energy, every point of the sun’s surface down to seven degrees south latitude and back again to its initial point, thus tracing a close spiral around the sun for fourteen degrees, or about one hundred and four thousand miles in width. The centrifugal force of the solar rotation piles up the photosphere and the chromosphere around the sun’s equator, precisely as our atmosphere is piled up around our own equator. If the planet be a large one (for distance has but little to do with these electrical currents at planetary distances, in which they differ entirely from light, heat, and gravity), or if there be two planets nearly in conjunction, the body of the chromosphere and the surface of the photosphere will gradually become highly heated, for currents of electricity, of themselves, do not directly heat the solar core any more than a like current heats the under carbon of an arc lamp, the high temperature in both cases being altogether due to the incandescent heat of the interposed arc or envelope. Faculæ of intense brightness will then appear upon the photosphere, and these will be driven forward and also outward in the direction of the higher latitudes, producing an oblique forward movement from difference of rotational speed at different portions of the sun’s surface. Similar phenomena are constantly observed on the surface of the earth in the generation and behavior of cyclones and other atmospheric disturbances. They may be compared to the wake of a vessel anchored in a strong tide-way. These faculæ will slowly raise the temperature of the surface of the sun’s core beneath to the point of eruptive volatilization, and particularly so if the planet is receding from, instead of advancing towards, the solar equator. At some point in advance of the line of planetary energy an eruption of volatilized metals will suddenly occur, first thrusting up a vast area of the photosphere and then bursting it asunder, which will drive these ruptured masses with enormous speed forward and obliquely outward from the equator. Such faculæ (see Proctor’s “Light Science”) sometimes reach a velocity of seven thousand miles per minute, while the sun’s rotational movement at the equator is less than seventy miles per minute. This sudden eruption will be almost immediately succeeded by great expansion and consequent fall of temperature, so that within a few hours the heavy volatile metals begin to condense and rapidly recede into their crater, and the faculæ in front and at the sides will now stream inward to occupy this vacuum with constantly accelerated velocity, pouring over the edges like the rush of waters at the Falls of Niagara. As they sweep downward over the inner rim of the funnel, these streams of faculæ will glow with increased whiteness, and appear to be sharply cut off at their inner ends; but this is only apparently so, and is due to the position of the observer, who looks almost directly downward upon these descending streams. It is for the same reason that the faculæ appear more brilliant when near the borders of the solar disk (see page 109). Any good view of a sun-spot when analyzed will show the streams of faculæ thus pouring inward, and they are among the most peculiar and conspicuous phenomena to be observed. The drawings of Professor Langley, reproduced in the Popular Science Monthly for September, 1874, and July, 1885, are particularly striking in their illustration of these effects, though their significance and interpretation were not then at hand.
Analysis of a typical sun-spot. Intersections of lines drawn between AA and MM, CC and MM, show state of active eruption; DD, inflowing faculæ pouring downward over the rim; PP, the same; OO and BB a floating bridge, partially completed, supported by the uprush, and along the line NN torn asunder, and upward into plumes and sprays. The general surface shows the mottlings and faculæ. The partial formation of a loop is shown at XX, YY. The line EQ represents the sun’s equator; from rear to front, the direction of solar rotation. The line of planetary impact is in rear.
But while these heavy metallic vapors so rapidly condense and subside in the forward or initial portion of the sun-spot under observation, new depths of intensely-heated faculæ are generated behind, and these operate with renewed energy upon the fresh surface of the solar core in rear of the original seat of eruption; so that each sun-spot, while in an active state, will exhibit two entirely distinct aspects, the forward portion of the crater in a state of rapid condensation and subsidence of the recently erupted metallic vapors, and with inflowing streams of incandescent hydrogen from the front and sides, and the rear portion of the crater up to its rearward wall, and even streaming forth from beneath it, in a state of violent eruption. The large volcanic craters of the Hawaiian Islands exhibit similar partial eruptions and subsidences progressing simultaneously in the same depths. The sudden formation of the great incandescent loops and plumes to which Professor Langley calls especial attention, and which have hitherto been so perplexing, can now be readily understood and explained. If one of these inflowing streams be carried partially down into and across the crater, and then caught, in its advance, by the uprush in the central or rear portions of the cavity, it will be at once swept upward alongside the ascending eruption, and either scattered at its forward extremity into sprays and plumes, or else thrown forward bodily in the form of a more or less complete loop. In a sun-spot fifty thousand miles in diameter, such a loop, having a long diameter of twenty thousand miles, if we give a speed to the faculæ of seven thousand miles per minute, would be formed in about seven minutes, during which the sun-spot would itself have advanced less than five hundred miles across the face of the sun. The luminous bridges which form so suddenly across portions of the crater may be explained in a similar manner: they are streams of faculæ floated on the nearly balanced uprush of metallic vapors from beneath.
