Hemisferium Planispheric Astrolabe Pendant Chain (Brass) H206
The Astrolabe, considered as the mathematical jewel of the Medium Age, was to the end of 17th century, the most used instrument in the whole history of Astronomy. It is still occasionally used today because it allows us to understand celestial mechanics and the apparent movement of the stars in a clear and simply way. Astrolabe, from the Greek, “star searcher”, was introduced to Europe by the Arabs in the early 12th century. It became a vital tool for astronomers, astrologers, and surveyors. This astronomical computer was used to estimate the time, to measure heights of celestial bodies and geographical accidents, determine the local latitude, estimate the sunrise and sunset time and to draw horoscopes. The astrolabe's importance not only comes from the early development of astronomy but is also effective for determining latitude on land or calm seas. It was less reliable on the moving deck of a ship in rough seas, so the mariner's astrolabe was developed to solve that problem. In the 9th century, Muslim astronomers improved the device by introducing angular scales and azimuth lines which added to its beauty. To use an astrolabe, the moving parts are first set to a specific date and a specific time. Once set, solar system objects are represented (both visible and invisible) in their relative positions on the instrument. The typical astrolabe was not a navigation tool, however. The similarly named 'mariner's' astrolabe was used for this purpose and was used widespread in the European Renaissance.