As far back as 1837 Joseph Smith said the moon was inhabited. "He described the men as averaging near six feet in height, and dressing quite uniformly in something near the Quaker style. In my patriarchal blessing, given by the father of Joseph the Prophet, in Kirtland, 1837, I was told that I should preach the gospel before I was 21 years of age; that I should preach the gospel to the inhabitants upon the islands of the sea, and — to the inhabitants of the moon, even the planet you can now behold with your eyes. The first two promises have been fulfilled, and the latter may be verified."
Oliver B. Huntington, Young Woman's Journal, vol. 3, p. 263-64