The Discovery of a World in the Moone by John Wilkins, 1638

The Discovery of a World in the Moone is a book by which John Wilkins (1614-1672)
The Moon and the visible Lunar features, new detail seen with the new telescopes, moon inhabitants and our potential means of travel thither. Very many others both English and French, all who affirmed our Earth to be one of the Planets, and the Sunne to be the Centre of all, above which the heavenly bodies did move, and how horrid soever this may seem at the first, yet it is likely enough to be true, nor is there any maxim or observation in Opticks ... that can disprove it... Now if our earth were one of the Planets (as it is according to them) then why may not another of the Planets be an earth?

Wilkins was one of the members of the Philosophical Society of Oxford and the Royal Society of London. "The Discovery..." is one of the first books of modern "popular science" genre.
He wrote it before the English Civil War. He later married Oliver Cromwell's sister and became the first secretary of the Royal Society.