Water on The Moon, I. Historical Overview

Abstract By mid-19th century, astronomers strongly suspected that the Moon was largely dry and airless, based on the absence of any observable weather. [1] In 1892, William H. Pickering made a series of careful occultation measurements that allowed him to conclude that the lunar surface’s atmospheric pressure was less than 1/4000th of Earth’s. [2] Any number of strange ideas arose to contradict this, including Danish astronomer/mathematician Peter Andreas Hansen’s hypothesis, that the Moon’s center of mass is offset by its center of figure by 59 kilometers, meaning that one or two scale-heights of atmosphere could hide on the far side of the Moon, where it might support water oceans and life. [3] Hans Horbiger’s 1894 Welteislehre (“World Ice”) theory, that the Moon and much of the cosmos is composed of water ice, became the favored cosmology of leaders of Third Reich Germany. [4] Respectable scientists realized that significant amounts of water on the Moon’s surface would rapidly sublime into the vacuum.