What is an armillary sphere used for?
The Armillary Sphere An armillary sphere is basically a skeletal celestial sphere with a model of the Earth or, later, of the Sun placed in the center. It is useful as a teaching tool and as an analog computer for solving various astronomical problems to a crude degree of accuracy.
What does a globe with an arrow through it mean?
An old astronomical instrument representing the ensemble of the celestial sphere and the movement of the celestial bodies. The central globe represents Earth, and the many concentric rings (armillae) the heavenly bodies. The arrow is directed towards the pole.
Is the armillary sphere still used today?
You can still purchase armillary spheres today, although some of them are extremely expensive, especially if they are antiques.
What is an armillary sundial?
Details Published: 13 September 2015 Hits: 14714. An armillary sundial also called an armillary sphere is a representation of both the terrestrial globe and celestial sphere. Often highly decorated, these are beautiful sundials.
How do you read an armillary sphere?
How to read the armillary sphere. Read the marks of the azimuth where it intersects the band of the horizon at 0 degrees (north) to determine for which degree of latitude the model is set. This information helps currents astronomers determine where one of the historical armillary spheres may have been made or used.
Why is it called armillary?
The English name of this device comes ultimately from the Latin armilla (circle, bracelet), since it has a skeleton made of graduated metal circles linking the poles and representing the equator, the ecliptic, meridians and parallels.
How do you use an armillary sundial?
Place the sundial on the base but do not secure it. Use the compass to locate true north and point the gnomen in that direction. For the greatest accuracy, the gnomon must point to magnetic north, not true north but to get a “ballpark” directional reading, a standard compass reading is fine.
Which way should an armillary face?
Find true north with your compass. Aim the axis (or gnomon) arrow of the armillary north. In the northern hemisphere, at night this arrow should point towards Polaris, the North Star.
Does an armillary sphere move?
Held stationary at the centre is a small brass sphere representing the Earth. About it rotate a set of rings representing the heavens – the celestial sphere – one complete revolution approximating to a day or 24 hours.
How do you read an armillary sphere ring?
How does an armillary tell time?
In use since Grecian times, armillaries are composed of complex, interlocking spheres supporting an arrow-shaped gnomon. As the sun travels across the sky, the gnomon casts a shadow onto a surface that indicates the hour. Armillary sundials are usually made of cast brass, bronze or aluminum.