Diagrammatic Representational Constraints of Spatial Scale in Earth–Moon System Astronomy Instruction

Given that astronomy heavily relies on visual representations it is especially likely for individuals to assume that instructional materials, such as visual representations of the Earth–Moon system (EMS), would be relatively accurate. However, in our research, we found that images in middle-school textbooks and educational webpages were commonly inaccurate in both: (a) the relative size of the Earth and Moon and (b) the relative distance between the Earth and Moon. More specifically, the students’ estimates, textbook images, and web images of the relative size of the Moon were too large, and of the relative distance were too small. We discuss these findings and provide recommendations to science educators.