Denison Olmsted of Yale — who turned the great meteor storm of 1833 into the founding study of meteor science — wrote Letters on Astronomy as a course of letters to an intelligent friend: the celestial sphere, the planets and comets, the fixed stars, all delivered with the patient courtesy of the epistolary classroom.
It is astronomy as polite education, and none the shallower for it. Download the free EPUB and take the course by correspondence, as the 1840s did.