An armillary sphere (variations are known as spherical astrolabe, armilla, or armil) is a model of objects in the sky (in the celestial sphere), consisting of a spherical framework of rings, centred on Earth, that represent lines of celestial longitude and latitude and other astronomically important features such as the ecliptic. As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations.

Contents

• 1 Description and use of the armillary sphere
• 2 History
  • 2.1 Hellenistic world
  • 2.2 East Asia
  • 2.3 Medieval Islamic world and Europe
  • 2.4 Renaissance
  • 2.5 Seamless celestial globe
• 3 See also
• 4 Notes
• 5 References
• 6 External links