Astronomy is fairly a new course for preservice science teachers in Turkey. Regardless of many science courses taken, preservice science teachers hold several misconceptions about astronomy. It is essential to find out those misconceptions to facilitate astronomy teaching. The aim of this study is to develop a new astronomy instrument specifically related to the topics of grade 4 through grade 8. The main reason for that is to find out preservice science teachers' astronomy misconceptions specifically related to these topics. Preservice science teachers wrote journals after each astronomy class during a semester and the test has been developed mainly based on these journals. After a pilot study, the instrument had reduced to 18 items. The cronbach alpha value determined as 0.71 for the main study. Data analyses showed that preservice science teachers hold several misconceptions about astronomy. The instrument is a multiple choice test, but in addition participants asked to state if they were sure or not sure of their answers at the end of each question. Results showed that the majority of preservice science teachers that gave correct answers were not sure of their answers.