earti-t's sphere of gravitative control 217 



serves to make more clear just what is meant by sphere of control, as the 

 term is here used — that is, control under the conditions of relative motion 

 of the bodies under consideration. Mouiton's concrete definition most 



R L. 



DIAGRAM III 

 I 



Scale obout 1,364,000,000,000 



Figure 3. — Diagram risualizing certain dynamic Distinctions much nearer the Earth-hody 



For relative scales compare R. L. of Diagram II with R. L. (Roche limit) of Diagram 

 III ; T. Z., limit between present tidal zones ; C. A., approximate transition zone between 

 the inner collisional atmosphere and the outer ultra-atmospheres, krenal and orbital ; 

 S. E., surface of earth. 



conveniently fixes in mind the essential conditions, "the space within 

 which a planet may hold a satellite," or the equivalent of this in gener- 

 alized terms. 



