Archaeoastronomy and cultural astronomy are often considered synonyms, but they actually express different concepts, the former being a sub-discipline of the latter. Cultural astronomy is a fascinating but controversial discipline, which serves as an auxiliary subject to social sciences such as history, archaeology, anthropology, and ethnography, among others. The tools and methodology of astronomy play a relevant role in the discipline, but it should be inserted within social sciences epistemology. Keywords SubjectsHistory of Ideas about Planets and Planetary Systems