Armillary Sphere

An armillary sphere is a model of objects in the sky, consisting of a spherical framework of rings, centered on Earth or the Sun, 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. It was invented separately in ancient Greece and ancient China, with later use in the Islamic world and Medieval Europe.

With the Earth as center, an armillary sphere is known as Ptolemaic. With the Sun as center, it is known as Copernican.The flag of Portugal features an armillary sphere. The armillary sphere is also featured in Portuguese heraldry, associated with the Portuguese discoveries during the Age of Exploration.