The etymological origin is the first thing we are going to discover about the word that we now have before us. Specifically, we can establish that astrolabe derives from the Greek, exactly from “astrolabion”, which is an instrument used to measure the stars and the height of the sun.
Exactly, it is the result of the sum of two terms of the aforementioned language:
-The noun “aster”, which is equivalent to “star”.
-The name “lambion”, which is synonymous with “handle”.
The term astrolabe refers to a device that was used in the field of astronomy in order to check the location of the stars. With the astrolabe, it was possible to indicate the height and position of the stars in the sky.
Astronomers and sailors, among others, used astrolabs to find the stars and analyze how they moved: in this way, they could obtain information about the hour and the latitude and even establish distance measurements.
The astrolabe was the navigation instrument most used for several centuries. Technological development, little by little, made it lose its preponderance. Today there are much more advanced tools that offer the information with greater precision.
Specifically, we can establish that the astrolabe became the fundamental instrument for navigators for many centuries. It was like this until the year 1750, approximately, when the sextant appeared on the scene. And it is that the latter had greater precision, hence it was used not only in the aforementioned maritime sector but also outside it and in other areas such as the air.
Although it is true that there is no specific data that establishes the name of the inventor of the astrolabe, all theories indicate that this is none other than the Greek mathematician Ptolemy (100 – 170). A figure is very important for his studies and advances in areas such as astrology, when creating horoscopes, as well as geography and optics, among other sectors.
However, it should not be overlooked that it is considered that other important personalities developed and perfected this original, such as Hypatia of Alexandria and her father, the astronomer Theon.
There were, however, various types of astrolabe. The planispheric astrolabe, for example, they could represent stars in a single latitude. Instead, universal astrolabe they had the ability to perform the representation in all the existing latitudes.
The operation of the astrolabe is based on the celestial sphere: an ideal type sphere that is concentric with the globe and where, apparently, the stars move. The instrument allows you to draw a stereographic projection, which consists of graphically representing the surface of the sphere in a plane.
The astrolabe is made up of a mother plate (a graduated circumference) with a needle pointing to the stars. The scale on the edge of the circumference can show degrees and time. In the front sector, two discs are inserted, one with the coordinates that correspond to a latitude and the other that rotates and that represents the locations of the Moon, the Sun and other stars.