This study examines the effect of the “Talking Planets” android mobile application (funded by the International Astronomical Union’s Office of Astronomy for Development) on school students from 4th to 9th grade and their attitude toward the application. Talking Planets is an educational android mobile application (currently in beta version, not available in Google play store yet) to make school children aware of astronomy, more specifically the planets of our solar system. This mobile application presents different planets as funny characters and students will be able to chat with these characters and find out about them by asking different questions. That is, the characters of the planets will behave like chatbots. In this study, students (n=79) from two schools used our developed mobile application, Talking Planets. The study was conducted on 15 and 17 March 2022. The study investigated whether students learned anything new about astronomy after using our mobile application. Students’ knowledge of astronomy was assessed before and after using the mobile application by providing the same question paper. 47.1% of students were able to increase their knowledge assessment performance, 35.44% of students’ performance did not change, and the remaining 16.46% of students’ performance was decreased. The outcomes suggest that this application has great potential to increase the knowledge of astronomy among school students. The attitude of the school students toward the mobile application was evaluated by an anonymous survey form. The students showed very positive attitude toward using the mobile application, its effectiveness, and user-friendliness.