In recent years information technology has been integrated into education to produce a series of trends, beginning with "electronic learning" (e-learning), through "mobile learning" (m-learning) and finally to "ubiquitous learning" (u-learning), which aims to improve learner motivation through overcoming the conventional limitations of time and location. U-learning practices are still being developed, and learners frequently experience difficulty focusing on learning objectives, and effective learning strategy tools are still lacking. This study reports the design of a context-aware astronomy learning system. The system integrates several technologies, including radio frequency identification, wireless communication networks, handheld mobile devices, and databases to help students learn astronomical concepts. Two content modules were developed in the context of natural science education for fifth-grade elementary school students in Taiwan. Indicators of user experience with the system were collected for further phenomenographic analysis, based on four perspectives of the Unified Theory of Acceptance and Use of Technology model to assess learner willingness to use this novel u-learning approach. Results show that ease-of-use and the availability of immediate operational or technical support are key factors in increasing learning motivation and performance.