Astrolabe is one of the most ancient astronomical instruments.
There are several types of this device, but in any case the principle of the astrolabe is stereographic projection.
Astrolabe is one of the first tools with which to determine the height of the Sun or stars, and on them - the coordinates of the point on the surface of the earth.
How is the astrolabe
In ancient times the astrolabe was called"The spider". It really looks like a spider. Its basis is a circle with a high rim, inside of which a disc with the lines of the celestial sphere plotted in the stereographic projection and points is embedded. In the center of the disk are built concentric circles - the pole of the world, the celestial equator, the northern and southern tropics. Marked on the disk is the celestial meridian, parallels and azimuth circles. An equalizing ring is used for leveling. "Spider" is a round lattice with the brightest stars on it, the zodiacal circle. The zodiacal circle has a scale. All parts are connected together by an axle.
The height of the Sun was determined with a ruler,Which is called "alidade". Then the observer turned the "spider", so that the desired points on the ecliptic and on a small circle, called "almukantarat", coincided. Due to this action, the stereographic projection of the sky at the moment was obtained on the outside of the device.
Originally from antiquity
The first astrolabe appeared in ancient Greece. Accordingly, from the ancient Greek language came and its name, literally translated meaning "he who takes the stars." One of the first detailed descriptions of this tool is Vitruvius in the book on architecture. He also indicates the name of the inventor - Evdoks, he is Apollonius of Perga. The instrument that Eudox invented was a drum with a starry sky depicted on it.
In that era there were several kinds of similarTools, they were not quite like the astrolabe of later eras. In its more or less modern form, this tool was made by Theon. This happened already in our era, in the fourth century. To the same era are treatises on this instrument. Astrolabe served as a tool for determining time.
From Greece the device got to the East. Arab scientists used it not only for astronomical, but also for mathematical purposes. In Western Europe during the Crusaders used the Arab astrolabe. Then the Europeans began to make such instruments themselves. There were also scientific works. One of the treatises was written by the great English writer Jeffrey Chaucer.
Basis of the basics
In the Renaissance, astronomy was extremelyPopular science. Any educated person should have known this science. In turn, the most important section of astronomy was the study of astrolabe. Instruments of the time were not only accurate, but also exquisite appearance. Collecting tools has become a good form, fashion. To this day, the royal collections have reached, which now adorn the world's largest museums. One of the most famous masters of the time - the Dutchman Gualterus Aresnius.