The Rotation of the Moon ¹

Abstract

AN interesting résum of the progress of our knowledge of the moon's rotation, together with considerable amount of original work, is given in the memoir before us. The author recalls the remarkable control. which the earth exerts on the rotation; the line joining the poles of the moon's equator and orbit always passes through the pole of the ecliptic, which lies between them, 1½° from the first, 5¼° from the second; both poles revolve round the pole of the ecliptic in 18.6 years. The earth's action has also forced the period of rotation to coincide with that of revolution the existence of this action is still in evidence from the fact that all secular and longperiod terms in the moon's revolution have their counterpart in the rotation; for; example, the secular acceleration in longitude has not the effect of making us gradually see a different hemisphere.