Nowadays, the importance given to astronomy teaching in science and physics education has been gradually increasing. At the same time, teachers play an important role in remediating the misconceptions about astronomy concepts held by students. The present study aims to determine the misconceptions of pre-service physics teachers (n=117), pre-service science teachers (n=97) and in-service physics teachers (n=174) about astronomy concepts using a three-tier test. The Astronomy Concept and Achievement Test (ACAT), developed by Trumper (2001a, 2001b, 2006), was adapted as a three-tier instrument and used as the data collection instrument. The first tier, first and second tier and all three tier responses that were obtained from the ACAT were analyzed separately to identify misconceptions and to evaluate the respondents‟ achievement. The results showed that the achievement scores of pre-service and in-service teachers considerably decreased when the third tier was considered. In addition, when the misconceptions of pre-service and in-service teachers were determined using all three tiers, they held extensive misconceptions especially about the reasons for seasons, the Moon‟s phases, the Moon‟s phase in the solar eclipse and the Sun‟s position in the sky.