Planetariums have been used for a long time in astronomy education. Due to some disadvantages of permanent planetariums, it is seen that portable planetariums have become popular in recent years. Portable planetariums, due to their easy set up in anywhere, offer opportunities for those students studying in the regions where there are not planetariums to learn about space and the puzzles about it. A portable planetarium activity which could be used in teaching of astronomy subjects was carried out in this study. The activity was planned considering the points that should be paid attention in out-of-school settings. After the study, the students' opinions about the portable planetarium activity were taken. When the student opinions are evaluated in general, it can be stated that the planetarium activity offered an opportunity for students to see the planets close, offered an enjoyable learning environment, caused students to enjoy science course and gave an opportunity to learn what they were curious about, and increased students' interest in science.