310 F. B. Taylor — Determinate Orbital Stability: 



an imaginary net ready to c^Ltch anything that came along, 

 and if some wandering planetoid (cometary nucleus), 

 revolving around the Sun in a more eccentric orbit than 

 that of the Earth, and with its aphelion close to the 

 Earth's orbit, were overtaken by the Earth it might pass 

 close enough to be strongly perturbed, and in so doing, it 

 might enter the satellite zone and be unable to escape, be- 

 ing retained thereafter as a permanent satellite. This, on 

 the present hypothesis, is the method of origin of all 

 satellites.-^ 



5. But in order to understand how systems holding 

 more than one satellite may grow, it is necessary to 

 consider another corollary. In a case like the Earth-Moon 

 system in which the planet already has one established 

 and well-regulated satellite, a second satellite may be 

 acquired and installed (if the satellite zone is wide 

 enough), in precisely the same manner as the first one, 

 except that during the process, the previously established 

 or first satellite is gradually driven out to a more distant 

 orbit, where, at the end of the process, if finds stable 

 revolution as the second satellite of the system. The 

 winding down of the orbit of the newly captured member, 

 and its installation in the determinate orbit as the nearest 

 satellite takes place concurrently with the expansion of 

 the orbit of the first satellite and its installation in a 

 larger orbit as the second satellite. 



It is practically impossible for the second satellite to be 

 inducted directly into stable revolution in an orbit outside 

 of the previously established, member, for this would 

 require at the outset a very small degree of eccentricity 

 and of inclination of plane, in combination with just 

 the right velocity and direction of motion — adjustments 



^ A capture hypothesis in some respects resembling that set forth here and 

 in my earlier writings is put forth with considerable elaborateness and with 

 mathematical treatment by T. J. J, See in his ''Eesearches on the Evolu- 

 tion of the Stellar Systems;'^ part II, ^'The Capture Theory," 1910. 

 See 's hypothesis differs fundamentally from mine in the fact that he makes 

 no mention nor any use of the principle of determinate orbital stability. 

 From my point of view, the winding down of the orbit of a planetoid during 

 capture and installation is accomplished through the forces which make 

 stability determinate, as stated above. See appears to rely wholly upon a 

 resisting medium in space for the winding down of orbits. For this reason, 

 he finds no determinate place for the orbit of the neAV satellite, nor any law 

 of growth for satellite systems. An inner limit to the satellite zone can 

 hardly be established by a resisting medium alone, nor can it furnish a 

 principle of adjustment for the second and later satellies of a growing sys- 

 tem. In See 's h^^pothesis, the later satellites are simply ' ' taken on, ' ' appar- 

 ently in random fashion. No details of the process are given. 



