The preceding papers have demonstrated the remarkable development of the radio-astronomical investigations of the solar system during the last few years. The subject of meteors has been intentionally excluded, since this is now far too extensive to be included in a symposium of this kind. The radio echo, or radar, techniques have now been extended to reach the moon, and a further extension to the nearer planets can be anticipated soon. In the meantime, the study of the thermal and nonthermal radio emissions from the planets is developing rapidly, and important new results have been presented here. It will be convenient first of all to consider the implications of the new work on the radio echo investigations of the moon.