The acquisition and development of knowledge about astronomy, in particular the Earth's shape and the night-and-day cycle, have been studied in several different cultural contexts. Research has shown that children have difficulty understanding these two counterintuitive notions, and that experience, presuppositions and cultural context all play an important part in their acquisition. Nevertheless, very few studies have looked at children's understanding of astronomy when different explanations for the same phenomenon coexist. This is the case in animistic cultural contexts, where the mechanistic knowledge acquired in the classroom differs from the knowledge conveyed by the cultural context. Astronomy is taught from Grade Three in both France and Burkina Faso. As the two curricula are identical, children are exposed to the same scientific, mechanistic facts at the same point in their schooling. We therefore chose to interview elementary schoolchildren in Grades One, Three and Five in France (mechanistic cultural context) and Burkina Faso (animistic cultural context), in order to study the ontogenetic development of the Earth's shape and night-and-day concepts according to the children's cultural context. We used the same questionnaire and similar interview conditions to question all 176 children who took part in this study. We formed the following two hypotheses: (a) schooling affects the nature and development of children's scientific knowledge, in that the older they grow, the more scientific and coherent their knowledge becomes; and (b) cultural context affects the nature and development of knowledge about astronomy. We showed that there is indeed a developmental effect, regardless of cultural context. Nevertheless, the French children acquired more scientific knowledge about the Earth's shape and the night-and-day cycle than the Burkinabe children did, and that knowledge was more coherent. Our results suggest that whereas the same scientific knowledge was transmitted through schooling in both cases, the children's acquisition and development of knowledge about astronomy was influenced by their cultural context (mechanistic vs. animistic). Children growing up in a mechanistic culture therefore develop a scientific understanding of astronomy earlier than children living in an animistic context, with the convergence of accounts from school and culture apparently facilitating and enhancing their scientific conceptualization of astronomy.