Some concepts of astronomy are taught at elementary school in France since 1985. More precisely, the program focuses on the day/night cycle, seasonal changes, solar system composition and size of the Universe. We are interested in this study by pre-service elementary teachers' conceptual understanding about those phenomena. We have addressed an open written questionnaire to 50 pre-service elementary French teachers about some basic astronomy notions they will have to teach as elementary teachers. We analyse their responses with regard to the elementary school programs and to the expected scientific conceptions. We show that those teachers have principally non scientific conceptions about the astronomical notions they will have to teach. For instance, the construction of the spherical earth model seems not plenty achieved.