This working model of the Earth Sun and Moon demonstrates the basic relationships of rotation, night and day. The Sun lights up and will shine on parts of the Earth and the Moon, simulating day and night. Each solar concept can be studied by moving the arm of earth or moon separately by hand while the arm mechanism maintains the correct ratio and relationship between the Earth, Moon & the Sun. Let students find out what time it is, what the difference is in seasons and why the days are shorter during some months compared to others.