KECENT COSMOGONIES 253 



planetary system. There are now known to be eight planets, 

 twenty-six satellites, and about eight hundred planetoids; prob- 

 ably the whole number of the latter may ultimately be found to 

 be a thousand or so. The average mass of these minor solar at- 

 tendants is thus only about 1/745,000 of the mass of the sun. 

 The average mass of the planets, neglecting the planetoids and 

 satellites, is about 1/6,000. Even the largest planetary mass is 

 less than a thousandth of the mass of the sun. It was not nec- 

 essary, therefore, that the sun should give forth even so much 

 as one- tenth of I per cent of its substance to form the largest 

 planet, assuming that the whole material for the planet was 

 ejected from the sun by a single impulse. The requirement for 

 the earth would be about one three-thousandth of I per cent of 

 the sun. It thus appears that the draft on the sun to supply the 

 substance of the planets was very small relatively. This suggests 

 that the passing star, if it had the mass we have chosen, must 

 surely have had such slight stimulating effect as the case re- 

 quired. We assume therefore only a quite distant approach. * * * 



Let it be assumed that the eruptivity of the sun was of the 

 same order then as now. At present, the sun is almost daily 

 shooting forth gas-bolts of vast dimensions and often at such 

 velocities that they rise many thousands of kilometers above its 

 glowing surface. Conservative computations assign these erup- 

 tive ejections velocities occasionally reaching one hundred or 

 two hundred kilometers per second, though the average speed is 

 less. Estimates by observers of high standing assign much 

 higher velocities in certain cases, some of these rising to several 

 hundred kilometers per second; indeed, velocities that surpass 

 the sun's power of control have been announced. * * * 



It is assumed that, at the time the nebula was formed, the 

 greater eruptions of the sun were concentrated, as now, in two 

 belts not far from the sun's equator. It is inferred that, as the 

 star approached from a distance, its first feeble stimulus led only 

 to moderate ejectments of sun-substance and that these suffered 

 so slight deviations by reason of the forward pull of the star that 

 they did not escape striking the sun's disk on their return and so 

 carried into the sun a little momentum acquired from the star. 

 This momentum neutralized an equivalent amount of the momen- 

 tum of the sun's rotation, then opposite to its present rotation. 

 With nearer approach of the star, the eruptions increased in 

 mass and vigor with increased effect on the sun's rotation. With 

 still nearer approach, a portion of the projectiles failed to strike 

 the sun's disk on returning and swung into orbits about it. Later, 

 a still larger part of the increasingly vigorous projectiles passed 

 into orbits, and these orbits grew broader, but certain portions 

 of the projectiles continued to return to the sun and affect its 

 rotation. 



