An armillary sphere is a model of the celestial sphere consisting of a framework of rings that represent lines of celestial longitude and latitude, the ecliptic, and other astronomically important features. Before the European telescope arrived in the 17th century, it was the prime instrument used by astronomers to determine celestial positions. It was also used as a teaching device and, in its mechanical forms, to demonstrate the motions of the sun and moon relative to the earth.
Who invented the armillary sphere?
The armillary sphere was invented independently in ancient China and ancient Greece. The Greek astronomer Hipparchus credited Eratosthenes, who lived from 276 to 194 BC, as the Greek inventor. In China, Joseph Needham traces the earliest development to the astronomers Shi Shen and Gan De in the 4th century BC, though the sinologist Christopher Cullen places Chinese origins at the 1st century BC.
Why is an armillary sphere on the flag of Portugal?
The armillary sphere became the personal heraldic badge of King Manuel I of Portugal in the late 15th century, before he took the throne, and its intense use during his reign transformed it from a personal symbol into a national one representing the Kingdom of Portugal and its Overseas Empire. The armillary sphere was reintroduced into the national arms and flag of Portugal in 1911 and remains there today.
What is the difference between a Ptolemaic and a Copernican armillary sphere?
A Ptolemaic armillary sphere has the Earth at its center, reflecting the geocentric model of the universe associated with the astronomer Ptolemy. A Copernican armillary sphere has the Sun at its center, reflecting the heliocentric model. Some armillary spheres were built with a mechanism allowing the user to demonstrate both the apparent motion of the heavens around a stationary Earth and the real motion of the Earth around a stationary Sun.
What was Zhang Heng's contribution to the armillary sphere?
Zhang Heng, the Chinese statesman, astronomer, and inventor who lived from 78 to 139 AD, completed the Chinese armillary sphere by 125 AD with the addition of horizon and meridian rings. He also created the world's first water-powered celestial globe, driving his armillary sphere using an inflow clepsydra clock.
What is the Honcheonsigye and why is it significant?
The Honcheonsigye is an armillary sphere activated by a working clock mechanism, built by the Korean astronomer Song Iyeong in 1669. It is the only remaining astronomical clock from the Joseon dynasty. Its timing device adopted the early 17th century pendulum clock system, making it a meeting point of Korean and Chinese astronomical tradition with Western clockwork engineering.