10 V. G. FESENKOV 



system. At present, the rotational moment of the Moon in its orbital motion 

 is nearly 75^0 of the total rotational moment of the whole system. This indicates 

 the importance of the role of the Moon in the dynamics of the Earth-Moon 

 system. Nothing resembling this can be found in the systems of the other planets. 

 For example, if we calculate the total rotational moment of Jupiter from the 

 internal distribution of densities and the known period of rotation, and if we 

 compare it with the sum of rotational moments of all of Jupiter's satellites, we 

 shall find that the latter does not exceed i-5"„ ofthat of the planet. The very 

 great importance of the orbital rotational moment of the Moon in the case of 

 the Earth is cogent proof that the Earth, in contrast to the other planets of the 

 solar system, originated as a double planet and therefore the process of its 

 formation should be very similar to the process of formation of double stars in 

 general. 



A binary star is formed from two closely situated centres of condensation in 

 one and the same primary gaseous-dust nebula whose total rotational moment, 

 as is usually the case, is too large for a single stable nucleus to develop. For this 

 reason the rotational moment must necessarily be distributed between two, or, 

 in some cases, among even a larger number of individual condensations. 



A similar assumption should be made with respect to the Earth. Thus, the 

 presence of our satellite signifies that by coming into existence the Moon took 

 upon itself the greater part of the total rotational moment of the whole primary 

 system, thus giving stability to the Earth. Without this the protoplanet of the 

 Earth would never have been able to solidify as a single body. 



However, the subsequent evolution of the Earth-Moon system evidently 

 proceeded in the direction of a sharp reduction of its reserve of rotational moment, 

 since at present it is already possible to add to the Earth the total rotational 

 moment connected with the orbital movement of the Moon without disturbing 

 the stability of the Earth. Indeed, the rotation period of the Earth would then 

 reach 4-4 hours whereas approximately 1-3 hours is sufläcient to disrupt the 

 stabihty. However, a decrease in the rotational moment can take place only in 

 the case of a decrease in the mass. 



To sum up, the conclusion may be drawn on the basis of the above-considered 

 facts that during its formation the Earth lost a substantial part of the original 

 mass. This explains the discrepancy between the Earth and the Sun in the 

 abundance of various elements in them despite the fact that both bodies must 

 have come from one and the same medium. Hence, the conclusion may be drawn 

 that the Earth's first atmosphere was entirely lost and that the present-day 

 gaseous shell is a secondary phenomenon. 



The chief factors responsible for this loss of mass of the protoplanet are its 

 temperature and initial mass. This immediately becomes clear if we compare 

 the different planets. In the biggest planet, Jupiter, with its mass 318 times that 

 of the Earth, the atmosphere is composed of 8o"o of hydrogen, I5"y of helium 

 and approximately 5% of the other heavy gases [3], thus bearing the closest 

 resemblance to the Sun. In the atmosphere of Uranus, hydrogen is second to 

 helium in abundance; in the surface layers of the Earth it occupies the eighth to 

 the tenth place, but is still present in sufficient quantities to form oceanic waters; 



