The purpose of this research is the determination of the effect of the activities of the planetarium on students' views, three-dimensional thinking skills and academic achievement. Mixed method was used in the research. The embedded pattern is preferred because qualitative data are supported by quantitative data that was used a single group pre-posttest experimental design. Homogeneous sampling was used in the study. A fully structured interview form and a three-dimensional thinking skill form have been prepared for the qualitative data. An academic achievement test has been developed for the quantitative data. Both descriptive and content analyses were done with frequency and Wilcoxon signed test techniques outside of the code-category and theme. Interpretation of the findings; as a result of planetarium activities in general, it has been found that the majority of students use positive expressions. It has been determined that the three dimensions skills of students is low in terms of size, distance and relationship dimensions between the Solar System and the planets. It has been determined that the same students' three dimensional thinking skills for the Earth and its satellite are high in size and distance dimensions but in relations and three dimensions complete are middle. It has been discovered that activities in the planetarium have increased academic achievement at both the seventh and eighth grade. Planetarium activities as a coincidence in the result of the research have an effect on eliminating the misconceptions of the students. Suggestions are made according to the study result.