33 



THE PLANETS.— THE SATELLITES. 



Earth, the two planets which follow each other 

 immediately. Mercury and Venus present the 

 same contrast in the excentricity of their orbits 

 which we observe in the four so closely alhed 

 asteroids. The excentricities of Juno and Pal- 

 las, which are very nearly alike, are three times 

 greater than those of Ceres and Vesta. It is 

 the same with reference to the inclination of 

 the planetary orbits to the plane of projection 

 of the ecliptic, and to the position of the axes 

 of rotation on their orbits, this position influ- 

 encing climate, season, and length of day, still 

 more than excentricity. The planets which 

 have the most elongated elliptical orbits, Juno, 

 Pallas, and Mercury, are also inclined in the 

 greatest degree, although not in equal meas- 

 ure, to the ecliptic. The orbit of Pallas is al- 

 most comet-like, and its inclination is nearly 

 twenty-six times greater than that of Jupiter ; 

 while the orbit of the little Vesta, which is so 

 near to Pallas, scarcely exceeds the angle of 

 inclination of the orbit of Jupiter six times. 

 The positions of the axes of the four or five 

 planets, whose axes of rotation are known with 

 any degree of certainty, also offer nothing like 

 regularity of series. Judging from the position 

 of Uranus's satellites, two of which (the 2d 

 and 4th) have recently been certainly seen 

 again, we should say, that the axis of Uranus, 

 the outermost of all the planets, was scarcely 

 inclined 11 ° to the plane of his orbit ; but Sat- 

 urn, whose axis of rotation almost coincides 

 with the plane of his orbit, revolves between 

 Jupiter, whose axis is nearly perpendicular, and 

 Uranus, where, as we have seen, it is but little 

 inclined. 



The world of planetary formations, in this 

 brief enumeration of the relations of these bod- 

 ies in space, is assumed as a fact, as a thing 

 that exists in nature, not as an object of intel- 

 lectual intuition, of internal causally-founded 

 concatenation. The planetary system, in its 

 relations of absolute magnitude and relative 

 position of axis, of density, time of rotation, 

 and different degree of excentricity of orbit, 

 does not strike us as naturally more necessary, 

 than is the measure of separation between the 

 land and the sea on the surface of our planet, 

 than are the outlines of its continents, or the 

 heights of its mountain-chains. In this respect 

 there is no general law discoverable either in 

 celestial space, or in the inequalities of our 

 earth's surface. The things that we meet with 

 are facts in nature, which have proceeded from 

 the conflict of multifarious forces in operation 

 under former and unknown conditions. But in 

 formation of the planets, man sees as accident- 

 al what he is incapable of explaining genetical- 

 ly. If the planets have been formed out of 

 separate rings of vaporous matter circulating 

 round the sun, differences in the density, the 

 temperature, and the electro-magnetic tension 

 of these rings, may have given rise to the most 

 diverse fashions of the conglobated matter ; in 

 the same way as the amount of the velocity of 

 projection, and trifling aberrations in the direc- 

 tion of the projection, may have given rise to 

 manifold forms and inclinations of the elliptical 

 Dibits. The attraction of masses, and the laws 

 of gravitation, have undoubtedly been at work 

 here, as in the geognostic relations of conti- 

 nental upheavings ; but we are not to draw 



conclusions from the present state of things, 

 as to the entire series of conditions which have 

 been passed through from their commence- 

 ment. Even the law, as it has been styled, of 

 the distances of the planets from the sun, the 

 progression from the failing member in which 

 Kepler was led to suspect the existence of a 

 planet betwixt Mars and Jupiter, has been found 

 incorrect numerically for the distances between 

 Mercury, Venus, and the Earth, and because 

 of a supposed first member, inapplicable to the 

 idea of a regular series. 



The eleven principal planets which have been 

 discovered circulating round the sun, are ac- 

 companied by at least fourteen, and very prob- 

 ably by eighteen, secondary planets (satellites 

 or moons). The primary planets are therefore, 

 in their turn, central bodies with reference to 

 subordinate systems. And here, in the struc- 

 ture of the universe, we recognize the same 

 formative process which the evolution of or- 

 ganic life so often exhibits to us in the ex- 

 tremely complex groups of animals and plants, 

 in the typical repetition of forms of subordinate 

 spheres. The secondary planets, or moons, oc- 

 cur in larger numbers in the outer region of the 

 planetary system, in connection with the three 

 great planets that lie without the zone formed 

 by the four telescopic planets. With the single 

 exception of the earth, all the planets within 

 this zone are moonless, and the satellite of the 

 earth is relatively of very large dimensions, in- 

 asmuch as its diameter amounts to one-fourth 

 of that of the earth ; whilst the largest of all 

 the secondaries known, the sixth of Saturn, is 

 not more perhaps than the yV^' ^^^ ^^^ largest 

 of Jupiter's moons, the third, is not above ^V^h 

 the diameter of its primary. The planets which 

 have the greatest number of moons are the 

 most remote, and they are, at the same time, 

 the largest, the least dense, and the most flat- 

 tened at the poles. The late measurements 

 of Madler seem to indicate Uranus as the plan- 

 et which is flattened towards the poles in the 

 greatest degree, ^.i^. In the earth and her 

 moon, whose mean "distance from one another 

 amounts to 237,000 English miles, the differen- 

 ces in the masses and the diameters of the two 

 bodies are much smaller than we are accustom- 

 ed to meet with them in the primary and sec- 

 ondary planets, and bodies of a different order 

 in the solar system('°). Whilst the density of 

 the earth's satellite is |-ths less than that of the 

 earth itself, it would appear, supposing we can 

 depend on the determinations that have been 

 come to on the magnitudes and the masses of 

 the satellites, that of the moons which attend 

 upon Jupiter, the second is denser than the pri- 

 mary planet. 



Of the fourteen satellites the relations of 

 which have been determined with something 

 like accuracy, the system of Saturn presents 

 instances of the most remarkable contrast in 

 the absolute magnitudes and distances from 

 the primary. The sixth satellite of Saturn is 

 probably not much smaller than Mars, whilst 

 the earth's moon is only one-half the diameter 

 of this planet. Next in order, in point of vol- 

 ume, to the two outermost satellites of Saturn 

 (the sixth and the seventh), comes the third 

 and brightest of the moons of Jupiter. On the 

 other hand, the two innermost satellites of Sat- 



