NATS 1745 Lecture Notes - Lecture 5: Armillary Sphere, Astronomy In The Medieval Islamic World, Ibn Al-Haytham

• School: York University
• Department: Natural Science
• Course: NATS 1745
• Professor: Robin Kingsburgh

Document Summary

An instrument that measures the altitude of stars and planets above the horizon. Islamic culture used this for an accurate measurement of stars positions. Outer ring marks degrees, so when leveled with horizon it can measure height of moon, sun, planets or stars that lies above horizon. From measuring angles to containing information about relationships on celestial sphere. Outer cosmos gets represented by celestial sphere, and that gets mapped to a local observer"s horizon. Also used another instrument- armillary sphere- which measured angles in 3d space. Other uses for these interments: you can mark time of day and seasons of year, find angle of sun moon stars and planets with respect to horizon or zenith, calculate heights of buildings and mountains, to survey the land. Instruments used extensively in greek and later in islamic astronomy. Determine direction of mecca (orient mosques, pray in right direction) Predict when crescent moon would be visible to start month.