He astrolabe It is a very popular element within the field of Astronomysince he himself knew how to be, especially in remote times, 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. Likewise, it was useful to know the time and latitude in which it was located..
Instrument used legendarily by scientists and sailors to locate themselves in the sea and to locate stars in the firmament
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 sunrise and sunset, 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 to: 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 even find a close link with religion, since Muslim navigators used it a lot during their trips to determine the location of Mecca and the time, and thus know what was the precise moment they should orient to where the astrolabe marked and so 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 rotates with a crosshair, which is pointed at the chosen star, while the edge of the motherboard, it has a scale graduated in degrees and in some astrolabes also in hours and minutes. Two disks are inserted in the front part of the motherboard, one internal or eardrum (fixed plate that contains the coordinates of the sphere engraved) and another external or spider (it has a transparent map with the positions of the sun, the moon and the brightest stars of the place). The needle that points to the star in question lies on the spider.
The type of stereographic projection proposed by the astrolabe implies a graphic representation system 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 surface it represents is greater than that of a hemisphere. When it comes to the polar projection, the meridians appear as straight lines, and the parallels as concentric circles.
classes of astrolabes
Various kinds of astrolabes were developed, the planispheric ones, which represented the stars in a single latitude, and the universal ones, which enjoyed the ability to represent all latitudes.
The heyday 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 ruled out when it is known that Hipparchus of Nicaeaprior to Ptolemy, already built the same and that even 5,000 years before these two characters, in the sumerian culturethe 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 in terms of location and location of stars for many centuries, but of course, the technological development that would come over the years made it lose power, precision, compared to other newer proposals, and then it ended up falling into 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 have been developed that make the astrolabe look like an obsolete invention today.
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