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The Pamphlet Collection of Sir Robert Stout: Volume 76

The Solar System

The Solar System.

73. Nebulæ must tend to entrap bodies passing through them. Such bodies would frequently become orbitally connected with the page 23 nebula. Then, when the nebula, with these bodies, became a sun, it would produce a system with planets in all azimuths, in the same way as the comets that our solar system has entrapped are in all azimuths.

74. Were a sun to impact with such a body or with a dense star-cluster, and were the graze considerable, all the planets would be whirled roughly into one plane, and the central mass would become a bun-shaped nebula.

75. It is not improbable that our sun was formed by an incipient star-cluster impacting with a nebulous sun, and that the present solar system constitutes a large part of the whole impacting mass. In other words, it is probable that there was not a large ratio of the original bodies dissipated into space during the impact, but it is probable that the impact was a large-ratio collision.

76. It is to be supposed that in every impact much matter will leave the system. Some of the gas extruded by the pressure acting along the axis will be lost, with much of the hydrogen. The attraction, therefore, on the return of the planets may be so much lessened by these losses that the orbits may be converted into an page 24 approximation to a circle. The nebula would expand enormously; all the matter of it that might pass outside aphelion distance would not aid in attracting the planet back. Perihelion distance would thus be increased by this agency.

77. Of course, at first the rotation on their axes of the newly-constituted planets would be in all possible directions. Thus, the axes may be in the ecliptic, or the motion may be retrograde. The order observed in the rotation of the inner planets will be established afterwards, the outer planets largely escaping these agencies.

78. Gaseous adhesion and many other agencies are at work to cause apsides to rotate. Consequently the larger nebular planets would gradually pick up all matter within the limits of their orbits, thus giving the rough order to the distance of the planets that is commonly known as Bode's law.

79. In a rotary nebula I have shown that much matter will tend to become meteoric. The absorption by a planet of every meteorite will tend to cause the planet to rotate in the common direction of the nebula, and will cause page 25 the axis to tend to become upright on the axial plane. This action will tell most with planets near the centre of the series, such as Jupiter and Saturn, because they will be largely gaseous and in the thick of the meteoric matter. The outer planets will necessarily be almost beyond the region of such influence, while the near ones will have but slight entrapping atmospheres, as explained hereafter.

80. All this exactly accords with the actual inclinations of the axes of the respective planets.

81. It is probable that the orbits of the planets were originally much smaller; but much of the potential energy of dimension would, as they shrank, be converted into energy of rotation, and this, by tidal action, into increased distance from the sun. The same may also be true of the moons.

82. As the volume of the nebula diminished its temperature would increase. An increased temperature would produce molecular exchanges between the planets and the nebula, and this would most affect the nearer bodies. Thus the near planets would lose all their light atoms by their escape into the surrounding nebula; whilst, on the other hand, the low velocity of the heavy page 26 molecules of the nebula would allow these molecules to be picked up by the planets.

83. Hence the near or inner planets would be small and dense, as we find them in our solar system, and the outer planets large and less dense, as in reality they are.

84. The heat of the contracting nebula will tend to increase the temperature of the planets, which would consequently expand. This would lessen their hold upon their light matter in two ways: (1) by the lessened attraction produced by expansion, and (2) by the increased velocity of the molecules themselves. The near planets would consequently be composed almost wholly of the heavy metals. The smaller and hotter any planets were, the greater would be their chance of being without atmosphere. The absence of this and the small volume of the planets would lessen their trapping action. Consequently they would not be so upright in their orbital planes as the middle planets.

85. The distant planets, being almost out of the nebula, would not collect an appreciable quantity of matter; hence the original axes of rotation may be at any angle, or even retro-grade, as, in fact, they are.

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86. As the nebula shrank within the orbits of the planets, the planets would again pick up light molecules that would form an atmosphere; but the temperature of the planets would not allow of much hydrogen being picked up unless it were in combination.

87. The resistance and contraction of the central nebula would clear space of all meteoric dust unless such were orbitally connected with a planet. The asteroids are probably parts of an exploded planet. The impact of a rapidly-moving body plunging into a planet could easily blow it to pieces. It has been suggested that, if so, such bodies would pass through the common point of their explosion. This idea is an error, as a planetary perturbation and other agencies would prevent such coincidence.

88. The trapping of their moons by the planets would probably occur when the planets were nebulous, and before the central nebula had attained to any great density. Hence they would lie roughly on the planet's equatorial plane.

89. Whilst a body of the mass of the earth could pick up an atmosphere, the smaller attractive power of the moon would not allow page 28 this at the temperature it would be at when its nebula contracted within its orbit. The moon would probably be much nearer the earth at first, but the stopping of its rotation by tidal action would increase the distance.

90. Many other agencies that would convert the system under discussion into one similar to our own are treated off in my paper on "Causes tending to lessen the Eccentricity of Planetary Orbits," in N. Z. Phil. Trans.