Concluding remarks
This Discussion Meeting was the first to review the many very interesting aspects of the rotation of bodies in the Solar System. During this session, the 200th anniversary of the death occurred of one of the greatest of all mathematicians, L. Euler, who, among other contributors to both pure and applied mathematics, established the laws of the rotation of solid bodies. Euler was born at Basle on 15 April 1707 and died at St Petersburg (Leningrad) on 18 September 1783. He worked as an Associate of the Academy of Sciences at St Petersburg on the invitation of Catherine the Great, with a period in Berlin as a Member of the Academy of Sciences on the invitation of Frederick the Great. Virtually all the papers given at this Discussion Meeting illustrate the fundamental principles he first enunciated. Studies of the variations of the Earth’s rotation, the discovery of which is a most interesting chapter of astronomy, have become a most important clue for understanding the motions in the Earth’s core responsible for generating the geomagnetic field and its secular variation, and now the shorter term variations accurately determined from modern techniques seem likely to similarly contribute to understanding the atmospheric general circulation. The rotation rate of Mars determined by astronomers from surface markings has been followed for over a century, but shows no such variations, partly because the methods so far available are not very accurate and partly because the core of Mars cannot be large.