## 1 Introduction
This can provide learners with a learning service using sensors to ascertain that learner's environment. In recent years, another new technology that has gained a lot of attention in the education field is Augmented Reality (AR). AR can be defined as an interactive technology that combines real and virtual information in any location-specific way [12]. Recently, a wide variety of fields have been using the AR technology, as it can effectively demonstrate the temporal concepts, contextual relationships, and spatial concepts between real and virtual information in the interactive environment. The benefits of using AR include the fact that virtual objects in AR view can be showed and can respond interactively to user actions, and that the virtual information or objects in AR view can overcome the limitations of location, time, and any other environment restrictions that can apply to real objects. Due to these merits, AR is becoming an effective educational technology [13]. Nowadays, most smartphones and tablets that have been equipped with GPS, compass, accelerometer, onboard sensors, etc. could assist the ideal indoor and the outside environment for AR experiences. Despite the limitations of GPS-based learning environments, for example, the fact that, sometimes, GPS accuracy is not good in the building compared to the outdoor environment, these smartphone platforms have been used by researchers and commercial developers to develop a number of effective educational systems [14]. Because of the above advantages of AR, smartphone AR is a powerful tool for astronomical phenomena observation learning, such as the lunar phase [15; 16], solar movement [17; 18], and stars [4; 19]. Moreover, in the app store and Google Play, there are a number of AR astronomy apps for observing stars that can be used in the outdoors, for example, Sky Map [20] and Star Walk [21] are very popular applications for astronomical learning. These applications identify the astronomical bodies, such as constellations, using the GPSand other sensors in the smartphone devices. However, these astronomical apps are not developed for teaching learners about seasonal constellations and they are unable to reach the educational goals of science regarding constellations in the planetarium and school. For example, there is no function to assist learners to observe and learn about seasonal constellations, such as the spring triangle. Secondly, there is no function for learners to understand the mechanisms of seasonal constellation. Finally, there are no suitable instructional strategies to specifically enable learners to engage actively in seasonal constellation observations with these applications. Refs. [15; 17] have developed a smartphone AR learning system for observing the lunar phase and solar movements based on the planetarium education method in the Nagoya City Science Museum. The experiment showed that two systems could assist learners in obtaining the benefits of a planetarium learning experience while also enjoying the benefits of directly observing actual astronomical phenomena. In order to solve these issues about seasonal constellation observation mentioned above, in this paper, we make use of smartphone device-based AR contents and 2D contents to develop a mobile learning system called the Real-World Oriented Smartphone AR Learning System (R-WOSARLS) for seasonal constellation observation based on planetarium contents, which can be applied to real constellation observations.