Celestial Sphere utilizes the earthly coordinate system of longitude and latitude to introduce key concepts of stellar navigation.  Observer based points of reference, such as the zenith, meridian and cardinal points, are contrasted with right ascension and declination. Other important concepts like the plane of the solar system, the ecliptic and the equinoxes are discussed. 

The Celestial Sphere - (2K license for theatres less that 125)