Page:The evolution of worlds - Lowell.djvu/81

Rh No; their envelopes are increasingly strange because their internal constituents are different, and as hydrogen is most abundant in Neptune, the lightest of all the gases, it is inferable that this planet's material is lighter. As distance from the Sun determines their atmospheric clothing, so distance decides upon their bodies, too. It was all a case of primogeniture. The light strange matter that constitutes them was so because it came from the outer part of the dismembered parent orb. Neptune the outermost, Uranus the next, then Saturn and Jupiter came in that order from the several successive layers of the pristine body, while the inner planets came from parts of it deeper down. The major planets were of the skin of the dismembered body, we of its lower flesh.

Very interesting the study of these curious spectral lines from the outer planets for themselves alone; even more so for what one would hardly have imagined: that they should actually tell us something of the genesis of our whole solar system. They corroborate in so far what the meteorites have to say.

That the meteorites are solid and, except for their experiences in coming through our air, bear no marks of external heat, is a fact which is itself significant. It seems to hint not at a crash as their occasioning but at disruptive tidal strains. The parent body appears to have been torn apart without much development of