This post was originally published on the Smithsonian Collections Blog.
Like any number of inventions, the origins of the armillary sphere are debated, credited to everyone from an ancient Greek philosopher to a Roman mathematician to a Chinese astronomer. The one commonality: it was created with the faulty supposition that the earth was the center of the universe!
Armillary spheres served as a model of the heavens with intersecting rings marking everything from latitude and longitude to the tropic of Cancer. (No wonder the name was derived from the Latin word ‘armilla’ meaning bracelet or ring.) Early spheres were fabricated out of wood but as they became more complex they were made of brass which withstood the elements out of doors. As with most objects of science, armillary spheres progressed as new discoveries were made. The Chinese used them to make calendar computations and calculations. During the Middle Ages, they served as sophisticated instruments used to map the solar system. Soon rings were added to mark the equator and the rotation of the sun, moon and known planets, making these spheres some of the first complex mechanical devices.
Because they were used outside where the sky was visible, armillary globes have become a common decorative feature in gardens. Today’s armillary spheres for garden use are strictly decorative in nature and much more streamlined than their ancient counterparts (think fewer rings inside the globe). While they no longer serve as a way to monitor the stars, they remain a symbol of progress and ingenuity throughout time.