Selenodesy and planetary geodesy



Selenodesy and planetary geodesy are here defined as the determination for the moon and the eight planets (other than the earth) of (1) the mass, either as the ratio thereto of the sun's mass, or as the product with the gravitational constant GM, (2) the radius R, (3) the rotation rate and orientation, (4) variations of the gravitational field, and (5) broad variations in topographic elevation. We divide this review into three parts: the moon, the inner planets, and the outer planets. The distinction is mainly one of accessibility: only the moon has been orbited by artificial satellites; all the inner planets have been probed by radar, and two have had close approaches by space vehicles; the outer planets as yet have been observed only by passive techniques.