"Though the solar system may seem complex,the sun is but a star among the millions in the Milky Way,and,compared with the planetary systems of Sirius,the stars of the Southern Cross,and the motions of the nebula,it is simplicity itself.Compared with the splendour of Sirius,with its diameter of twelve million miles,the sun,measuring but eight hundred and forty thousand,becomes insignificant;and this giant's system includes groups and clusters of planets,many with three times the mass of Jupiter,five and six together,each a different colour,revolving about a common centre,while they swing about their primary.Their numerous moons have satellites encircling them,with orbits in some cases at right angles to the plane of the ecliptic,so that they shine perpendicularly on what correspond to the arctic and antarctic regions,while their axes are so inclined that the satellites turn a complete somersault at each revolution,producing glistening effects of ice and snow at the poles.Some of the moons are at a red or white heat,and so prevent the chill of night on the planets,while they shine with more than reflected light.In addition to the five or six large planets in each group,which,however,are many millions of miles apart,there is in some clusters a small planet that swings backward and forward across the common centre,like a pendulum,but in nearly a straight line;and while this multiplicity of motion goes on,the whole aggregation sweeps majestically around Sirius,its mighty sun.Our little solar system contains,as we know,about one thousand planets,satellites,and asteroids large enough to be dignified by the name of heavenly bodies.Vast numbers of the stars have a hundred and even a thousand times the mass of our sun,and their systems being relatively as complex as ours--in some cases even more so--they contain a hundred thousand or a million individual bodies.
"Over sixty million bright or incandescent stars were visible to the terrestrial telescopes a hundred years ago,the average size of which far exceeds our sun.To the magnificent telescopes of to-day they are literally countless,and the number can be indefinitely extended as your optical resources grow.Yet the number of stars you see is utterly insignificant compared with the cold and dark ones you cannot see,but concerning which you are constantly learning more,by observing their effect on the bright ones,both by perturbing them and by obscuring their rays.
Occasionally,as you know,a star of the twelfth or fifteenth magnitude,or one that has been invisible,flares up for several months to the fourth or fifth,through a collision with some dark giant,and then returns to what it was in the beginning,a gaseous,filmy nebula.These innumerable hosts of dark monsters,though dead,are centres of systems,like most of the stars you can see.
"A slight consideration of these figures will show that,notwithstanding the number of souls the Creator has given life on earth,each one might in fact have a system to himself;and that,however long the little globe may remain,as it were,a mint,in which souls are tried by fire and moulded,and receive their final stamp,they will always have room to circulate,and will be prized according to the impress their faces or hearts must show.
But Sirius itself is moving many times faster than the swiftest cannon ball,carrying its system with it;and I see you asking,'To what does all this motion tend?'I will show you.Many quadrillions of miles away,so far that your most powerful telescopes have not yet caught a glimmer,rests in its serene grandeur a star that we call Cosmos,because it is the centre of this universe.Its diameter is as great as the diameter of Cassandra's orbit,and notwithstanding its terrific heat,its specific gravity,on account of the irresistible pressure at and near the centre,is as great as that of the planet Mercury.This holds all that your eyes or mine can see;and the so-called motions of the stars--for we know that Sirius,among others,is receding--is but the difference in the rate at which the different systems and constellations swing around Cosmos,though in doing so they often revolve about other systems or swing round common centres,so that many are satellites of satellites many times repeated.The orbits of some are circular,and of others elliptical,as those of comets,and some revolve about each other,or,as we have seen,about a common point while they perform their celestial journey.A star,therefore,recedes or advances,as Jupiter and Venus with relation to the earth.The planet in the smaller orbit moves faster than that in the larger,so that the intervening distances wax and wane,though all are going in the same general direction.In the case of the members of the solar system,astronomical record can tell when even a most distant known planet has been in opposition or conjunction;but the earth has scarcely been habitable since the sun was last in its present position in its orbit around Cosmos.The curve that our system follows is of such radius that it would require the most precise observations for centuries to show that it was not a straight line.
"We call this the universe because it is all that the clearest eyes or telescopes have been able to see,but it is only a subdivision--in fact,but a system on a vaster scale than that of the sun or of Sirius.Far beyond this visible universe,my intuition tells me,are other systems more gigantic than this,and entirely different in many respects.Even the effects of gravitation are modified by the changed condition;for these systems are spread out flat,like the rings of this planet,and the ether of space is luminous instead of black,as here.These systems are but in a later stage of development than ours;and in the course of evolution our visible universe will be changed in the same way,as I can explain.
