The successful launching of artificial satellites has inaugurated a new era in planetary astronomy. Already a greatly improved model for the uppermost layers of the terrestrial atmosphere has resulted [i] which has repercussions on the general problem of escape of planetary atmospheres to space. The interaction of planetary atmospheres with the interplanetary gas flowing from the Sun and the effects of planetary magnetic fields on the motion of this gas promise to be clarified next. The surface of the Moon, of such great interest to both planetary astronomy and geophysics, may soon be accessible to direct exploration. A much-broadened interest in planetary astronomy has resulted. Progress has not been limited to these spectacular developments. Radio astronomy has progressed to the point where both extremes of the spectrum transmitted by the atmosphere (A~i cm and 15 meters) are well observable for some of the planets; and radar pulses reflected by the Moon have been recorded in such detail that they aid materially in the study of its surface texture. Nor have the more conventional approaches-visual, photographic, photo-electric, polarimetric, and spectroscopic-been lacking in important results. Books or monographs were published on the following topics: The Planet Jupiter, by B. M. Peek [2]; Transfer of Radiation in the Atmospheres of Stars and Planets, by V. V.