A curriculum to train teacher candidates is a very important factor in developing teacher candidates' conceptual understanding of scientific concepts. Teacher candidates have a dramatic impact on students' ability to understand and construct new knowledge of the concepts. The purpose of this study was to determine the preconceptions and misconceptions of teacher candidates about basic astronomy concepts. This was measured by administrating the validated diagnostic questions from the latest version of the Astronomy Diagnostic Test 2.0 - 113 teacher candidates in the School of Education in Amasya University, Turkey. The findings indicated that teacher candidates held a series of misconceptions on several basic astronomy concepts. Common misconceptions were identified and a constructivist-inquiry approach to teaching basic astronomy concepts in the astronomy curriculum for pre-service teachers was proposed.