The astrolabe is a very popular element within the field of Astronomy, since he himself knew how to be, especially in ancient times, a A location instrument during navigation that represented the celestial sphere with its main stars and was then very useful when observing and determining the height, position and movement of the stars on the horizon. It was also useful to know the time and latitude in which it was.
Instrument used legendarily by scientists and navigators to locate themselves at sea and to locate stars in the sky
In short and concrete accounts, what the astrolabe allows is to determine the position of the stars, calculate the time, the hour, the time of the sun, the rising and setting of the sun, and the location of the moon and the rest of the planets
The term astrolabe has a Greek origin, which precisely coincides with its purpose, since it refers: star finder.
Uses and applications
Mostly, it was used, of course by navigators, but also by astronomers and scientists to be able to locate the stars in space, observe their movements and also to know the time and latitude, as we mentioned above.
We can also find a close connection with religion, since Muslim navigators used it a lot during their travels to determine the location of Mecca and the time, and thus know what was the precise moment they should orient themselves to where the astrolabe marked and thus perform the usual prayer.
How does it work?
Technically, the astrolabe is based on a stereographic projection of the celestial sphere, which consists of a graduated circumference or mother plate on whose axis a needle with a crosshair rotates, which is pointed at the chosen star, while the edge of the motherboard, it presents a scale graduated in degrees and in some astrolabes also in hours and minutes. Two discs are inserted in the front of the motherboard, one internal or eardrum (fixed plate that contains engraved the coordinates of the sphere) and another external or spider (It has a transparent planisphere with the positions of the sun, the moon and the brightest stars in the place). Above the spider lies the needle that points to the star in question.
The type of stereographic projection proposed by the astrolabe implies a system of graphic representation in which the surface of the terrestrial sphere is projected onto a plane through a series of lines that pass through a point. The plane is tangent to the sphere.
The area it represents is larger than that of a hemisphere. In regards to the polar projection, the meridians appear as straight lines, and the parallels as concentric circles.
Astrolabe classes
Diverse classes of astrolabe were developed, the planispheric ones, that represented the stars in a single latitude, and the universal ones that enjoyed the capacity to represent all the latitudes.
The apogee of its implementation at the behest of navigation was located between the centuries XVI and XVIII, until in 1750 it was superseded by the creation of the sextant.
Origins and creation
Regarding its creator, there are several controversies, some point to the astronomer and mathematician Claudius Ptolemy as its author, although, such a version is practically discarded when it is known that Hipparchus of Nicaea, prior to Ptolemy, was already building them and even 5,000 years before these two characters, in the Sumerian culture, the use of the aforementioned astrolabe already existed.
Meanwhile, the oldest astrolabe that to this day is preserved in the National Museum of Kuwait, dates from the year 927 and was built by the astronomer of Persian origin Nastulus.
This navigation instrument of course knew how to be the star for many centuries in terms of location and location of stars, but of course, the technological development that would ensue over the years made it lose power, precision, compared to other newer proposals, and then it ended up being in disuse, and so it is that today it is preserved in memory and in history but it no longer has an active use by navigation or science.
In terms of location and location in space of various elements, technology has advanced fantastically and modern equipment and devices were developed that today make the astrolabe an obsolete invention.
