between 1925 and 1928 milanković wrote the popular-science book "through distant worlds and times" in the form of letters to an anonymous woman. the work discusses the history of astronomy, climatology and science via a series of imaginary visits to various points in space and time by the author and his unnamed companion, encompassing the formation of the earth, past civilizations, famous ancient and renaissance thinkers and their achievements, and the work of his contemporaries, köppen and wegener. in the "letters", milanković expanded on some of his own theories on astronomy and climatology, and described the complicated problems of celestial mechanics in a simplified manner.