Same as MM20 but without light
These desktop models are used to demonstrate
sun-earth-moon relationships and
are recommended for those just beginning
to make their acquaintance with astronomy.
Each concept can be shown individually
moving the arm, earth, moon by hand.
Shows basic relationships of rotation,
revolution, night and day, seasons and
more. The twilight zone ring enables one
to understand the nature of dawn and dusk. Chain/gear drive maintains
the north pointing axis of the earth. Wood base with plastic spheres and
metal drive. A detailed illustrated instruction manual is included.