-DIASTROPHISM AND THE FORMATIVE PROCESSES — 405 
46. Planetary generation by the dioecious method is not 
confined to the approach of one star to another; bodies less massive 
than stars, if they make sufficiently close approaches, are compe- 
tent to develop planetary systems. Only 1/745 part of the mass of 
the sun was required to form the planets of our system. The 
critical point in such cases is the ability of the small passing body 
to impart the requisite revolutionary momentum.' 
47. New potentialities of projection from the sun have recently 
been disclosed. Twice during 1919, Pettit observed that erupted 
calcium vapor ascended by a@ succession of accelerating impulses. 
In one case, the ejected calcium vapor increased its outward 
velocity from 5.5 kms. per second to 60 kms. per sceond; in the 
other, from 37 kms. per second to 163.9 kms. per second. In both 
cases, the calcium was moving at its highest velocity when it ceased 
to be visible, high above the sun, probably either from cooling or 
from scattering, or both.’ 
DIVERGENCIES IN THE MODES OF PLANETARY CONDENSATION 
48. The planetary nuclei diverged into two lines of descent 
almost as soon as they emerged from the sun. The nuclei that 
were massive enough to remain hot and gaseous at all stages, and 
to hold practically all molecules that came within their control, 
naturally grew to be giant planets. Nuclei that were not massive 
enough to hold all the solar gases, but in the main only the heavier 
ones, such as later made up the stony and metallic bodies, followed 
a much more selective career. This was a very vital matter, for 
the solar gases, constituted as they were, could not condense 
directly into bodies of the composition of the earth; a preliminary 
sifting was indispensable. 
49. A further divergence soon followed in this sifted class. A 
few of the larger nuclei were only incompletely sifted; so that they 
retained relatively small amounts of gases of the atmospheric 
”) 
t“Multiple Phases of the Planetesimal Hypothesis,” zbid., pp. 149-50. 
2 Recent Disclosures Bearing on the Solar Parentage of the Planets,” zbzd., 
Pp. 145-49; Edison Pettit, “‘The Great Eruptive Prominences of May 29 and July 15, 
1919,” Astrophys. Jour., Vol. L (October, 1919), pp. 206-19. 
3 “The Physical Phases of the Planetary Nuclei during Their Formative Stages,” 
Article XII, Jour. Geol., Vol. XXVIII (1920), pp. 481, 487-80. 
