I. The kinetic theory of planetary atmospheres

Abstract

1. The possibility of applying the Kinetic Theory to account for the presence or absence of different gases in the atmospheres surrounding the various members of our Solar System, and in particular to explain the absence of any visible atmosphere from the Moon, was first discussed by Waterston in 1846, in his memorable paper on “The Physics of Media,” that so long remained unpublished in the archives of the Royal Society. This application of the theory is distinctly mentioned in the abstract of Waterston’s paper published in 1846, which is reproduced by Lord Rayleigh as an appendix to the paper itself. Hence we may say that the kinetic theory of planetary atmospheres is as old as the kinetic theory of gases. The present subject received the attention ot Dr. Johnstone Stoney somewhere about the year 1867. It was brought under my notice by a note written by Sir Robert Ball in 1893, and in that year I read a paper before the Nottingham meeting of the British Association on “The Moon’s Atmosphere and the Kinetic Theory,” in which numerical results were obtained sufficing to account for the absence of a visible atmosphere on the Moon and the existence of such gases as hydrogen in presence of the Sun. At that time, however, I did not see clearly how to take account of axial rotation, which evidently might play an important part in whirling off the atmospheres from certain planets, and thus the results given only represented the state of affairs at points along the polar axes of the bodies in question. Owing to this objection I did not deem it desirable to publish a more detailed paper than the abstract which appeared in the Nottingham Report.