Armillary spheres were used well into the seventeenth century to teach the concepts and coordinate systems of spherical astronomy. The Earth is at the center, and rings represent the horizon, equator, tropics, ecliptic, and important colures. The "cage" as a whole rotates around the axis of the celestial poles. An armillary can be used to demonstrate, for example, the azimuths and angles at which the sun rises and sets at different times of the year.

Armillary spheres sometimes incorporate models explaining the motion of the Sun, the Moon, or other planets.