Description
The question, “What shape is the Moon today, and when and where can it be seen in the sky?” is a difficult one. In Japan, many adults might struggle to answer it. However, most of them know that the Moon’s phases occur as a result of the Moon reflecting sunlight and orbiting the Earth. Some children even believe that different shaped moons exist in space and that a different Moon appears in the sky every day. Currently, knowledge of Moon phases is not widely useful for either children or adults. We believe this is an important topic for science museums.
This paper introduces a Moon phase simulation experiment, which has been well received when conducted at our science museum for audiences from young children to adults. Furthermore, performing this experiment in elementary and middle school classes would enhance students' understanding of Moon phases.
The fundamental principle of this experiment is that when sunlight illuminates the spherical Moon, only the hemisphere exposed to sunlight appears bright. Using this foundational concept, this experiment aims to help participants understand the mechanism behind Moon phases.
When explaining Moon phases, we (especially adults) tend to describe the phenomenon based on the heliocentric positions of the Sun, Earth, and Moon in order to prioritize accuracy. However, at the science museum where this experiment was conducted, many visiting families include young children or elementary school students. For this reason, complex explanations were intentionally avoided. Instead, we designed a simulation that could be intuitively understood by both children and adults.
The experiment involves preparing a spherical Moon model, with one half painted yellow and the other half painted black. By placing this Moon model at various positions on a panoramic board depicting a terrestrial landscape, the appearance of Moon phases as observed from Earth can be replicated on a tabletop. The objective of this simple experiment is to help participants understand patterns in Moon phase changes. In other words, the experiment aims to help participants recognize the relationship between the Moon’s apparent shape (phases) and its relative position to the Sun.
Given that the phrase “the apparent distance of the Sun and the Moon” may be difficult for young children to grasp, alternative expressions such as “the Sun and Moon appear close together” or “they appear far apart” were used. As a result, both young children and elementary school students were able to understand the concept with ease.
This simulation experiment emphasizes a ground-based observational perspective, allowing participants to experience where the Moon appears in the sky and in what shape. To simplify conditions, the experiment was restricted to the Moon at dusk. This approach allowed us to focus solely on the changing position of the Moon while keeping the positions of the Sun and Earth fixed, thereby enabling a straightforward understanding of Moon phases.
Finally, we propose the use of this simulation experiment in elementary and middle school science classes. Conducting the experiment of dusk and dawn hours allows students to observe how the Moon’s phase changes as it revolves around the Earth.
School textbooks in Japan commonly show the illustrations of Moon phases as seen from space (far above the Earth). This experiment replicates the illustrations, so it can help students who may struggle with perspective shifts. As a result, students can develop a more intuitive grasp of Moon phases.
