As regards the influence of comets on planets, instead of comets exercising any influence on the motions of planets there is most conclusive evidence that the converse is the case—that planets disturb the movements of comets. This fact is strikingly exemplified in the history of the Comet of 1770 just mentioned. After its discovery it was found
Fig. 27.
DIAGRAM ILLUSTRATING THE INFLUENCE OF JUPITER ON COMETS.
to be moving in an elliptical orbit requiring for a complete revolution only 512 years; yet though this comet was a large and bright one it had never been observed before, and it is doubtful whether it has ever been seen since, the reason being that the Planet Jupiter completely changed the character of its path, probably by enlarging it.
