France is among the few countries that have integrated astronomy in primary school levels. However, for fifteen years, a lot of studies have shown that children have difficulties in understanding elementary astronomic phenomena such as day/night alternation, seasons or moon phases’ evolution. To understand these phenomena, learners have to mentally construct 3D perceptions of aster motions and to understand how light propagates from an allocentric point of view. Therefore, 4-5 grades children (8 to 11 years old), who are developing their spatial cognition, have many difficulties to assimilate geometric optical problems that are linked to astronomy. To make astronomical learning more efficient for young pupils, we have designed an Augmented Inquiry-Based Learning Environment (AIBLE): HELIOS. Because manipulations in astronomy are intrinsically not possible, we propose to manipulate the underlying model. With HELIOS, virtual replicas of the Sun, Moon and Earth are directly manipulated from tangible manipulations. This digital support combines the possibilities of Augmented Reality (AR) while maintaining intuitive interactions following the principles of didactic of sciences. Light properties are taken into account and shadows of Earth and Moon are directly produced by an omnidirectional light source associated to the virtual Sun. This AR environment provides users with experiences they would otherwise not be able to experiment in the physical world. Our main goal is that students can take active control of their learning, express and support their ideas, make predictions and hypotheses, and test them by conducting investigations.