Where previous studies have shown the existence of misconceptions in astronomy, this research focuses on the level of awareness that teachers have of these misconceptions and the possible strategies they use to change the students' mental models. Through focus group interviews with secondary school teachers and semi-structured interviews with teacher managers, this latent knowledge is made more explicit. The main findings suggest that the level of awareness about misconceptions varies considerably among the teachers. In general, the same pattern is found for the teacher managers. Some mental models, for example, the distance model are known by all the teachers whereas others are not known at all. Even though teachers acknowledge the importance of students' preconceptions in general, they have difficulties using their students' prior knowledge in an effective way in their teaching practice. According to the teachers, this is mainly due to a lack of time and difficulties experienced with differentiation. Suggestions are made to raise awareness on the one hand via teacher managers and teacher training programs for preservice, as well as inservice, teachers and to avoid further misconceptions on the other hand via a proper use of images in textbooks.