Recent emphasis on advancing STEM education has led to the exploration of various learning opportunities essential for nurturing scientifically and technologically literate individuals equipped with 21st-century skills. Augmented Reality (AR) stands out as a technology with promising educational benefits in STEM fields, offering engaging and scientifically valid content for young learners. This study explores the multifaceted impact of AR technology on elementary students’ educational experience, encompassing engagement in learning, affective state, and cognitive acquisition of fundamental astronomy concepts. Thirty-nine elementary school students participated in the study, divided into experimental and control groups, engaging with either a book-based instruction or the AR application to explore solar system themes. For classroom mood evaluation this study provided rather straightforward results. Both the control intervention and the actual AR educational intervention impacted, in a measurable positive way, the affective state of the class. However, we did not find any significant differences in these positive changes between the control and experimental group. Additionally, the visual, tacit impact of the AR application was strong enough to provide a measurable, statistically significant difference between knowledge retention in the experimental and the control group. Further investigation of this process and refined versions of the AR applications with larger participant pools will facilitate the development of a validated tool to support astronomy education in elementary schools. It will also streamline the evaluation process for integrating AR educational resources into the curriculum.