2 Ounce Silver Cook Islands 2023 Antique Finish - ASTROLABE Historical Instruments - 10 $ - Smartminting UHR- 1st Issue

2 oz Cook Islands 2023 Antique Finish - ASTROLABE -
Historical Instruments - 10 $ - Smartminting UHR

New Series : Historical Instruments

Minatge  1,500 - Delivery in original packaging from Coin-Invest-Liechtenstein

The ASTROLABIUM is the 1st issue of the new series "Historical Instruments", dedicated to the best historical technologies.

The motif side shows a beautiful astrolabe, an early scientific instrument used for time calculation and observation purposes. Astrolabes represent a unique blend of science and myth, revealing the logic of an earlier time when people were still trying to make sense of the natural world. The design also includes ancient characters and the inscriptions: "ASTROLABE" - the name of the coin and "2023" - the year of issue.

The heraldic side of the coin features the effigy of Her Majesty Queen Elizabeth II and the inscriptions: "ELIZABETH II" - the Queen's name, "COOK ISLANDS" - the Island.

Technische Daten - Coin Data :

2023 Cook Islands  10 NZ$  Antique Finish 
2 oz = 62,2 g .999 Silver  Mintage 1,500
Smartminting Technologie
Original Packaging Coin-Invest-Liechtenstein

The Astrolabe

Originally, Arsineus' astrolabe was designed for latitude 41 and functioned accordingly between latitudes 38 and 43 north, but these models also have an insert for latitude 50. Germany lies between latitudes 47 and 55 degrees north. As is well known, the 50th degree of north latitude runs through the city centre of Mainz. The inscriptions are in Latin. Below you will find a downloadable insert for 48.5° north latitude, which you can print out. It was kindly made available to us by a customer.

An astrolabe, also called a stargazer, is nothing more than a complex, rotatable star chart. It can be used to determine not only the position and the rising and setting times of the sun or some bright stars, but also the date and time. How to use the astrolabe is clearly explained in the instructions below (download as PDF). You will also find a template for the 50th parallel to print out and cut out, which was created by a customer. A hole punch makes a hole of the right size in the middle of the disc.

It is said that the astrolabe once had over 1000 possible uses - at least that is what the Arab astronomer al-Sufi reported in a 386-chapter work on this ancient aid. The number may be too high and may also be due to the fact that he listed not only astronomical applications, but also astrological, geographical, nautical and religious ones. In any case, it is certain that the astrolabe is an extremely versatile aid, a true astronomical "multitool" that combines a star chart, slide rule and measuring tool.

How the astrolabe works

Classical astrolabes were usually made of bronze or brass and usually had a diameter of 15 to 20 cm, although much larger and smaller ones were also made. No doubt many astrolabes were also produced from cardboard and paper.

On the front of the astrolabe there are two types of parts: graphic time tables and the stereographic projection of the sky for a given latitude. The rotating parts simulate the daily rotation of the sky.

Mater and discs

The main part of a typical astrolabe consists of a bronze disc about six millimetres thick with a ring-shaped depression in the centre. The ring around the edge of the disc (Latin: limbus) is divided into degrees and on many European astrolabes into 24 hours, with noon at the top and midnight at the bottom. Astrolabes from the Islamic world usually had no hour indication. In the recessed centre of the disc (the mater, Latin: mother) sits the plate for the local latitude (also called the climate or tympan). It bears circles for the degrees of altitude as well as the directional angle for a given latitude. Older instruments have different interchangeable discs with engravings on both sides so that the instrument can be used at different latitudes. The disc closest to the user's latitude was used.

Rete

Above the plate is a disc with various openings (the rete, Latin for net) so that the plate can be seen underneath. Spikes in the openings mark certain fixed stars. A circle shows the projection of the sun's path in the sky (ecliptic). The ecliptic circle is divided into 30 degree sections representing the signs of the zodiac. One rotation of the rete simulates the rotation of the stars in the sky during a day. At the top of the rete is a pointer. Not all astrolabes had a pointer; this depended on the intended use. The pointer and the rete were held in position by a pin through the centre of the instrument and could be rotated above the plate. The pin is held in position by a wedge (shaped like the head of a horse - screws had not yet been invented).

The rete was corrected for our time because the stars were positioned differently 400 years ago. There are special computer programmes to adjust these deviations on astrolabes.

Suspension

A string, connected to a ring at the top of the astrolabe to take measurements of the sun or a star, kept the whole instrument suspended. The top of the instrument where the ring was attached was called the throne (kursi in Islamic instruments). In European instruments, the holding device was equipped with a swivel joint, called the armilla (Latin: ring).

The back of the astrolabe

The back of the instrument contained engravings with different scales depending on when and where the astrolabe was made. All astrolabes had scales for measuring angles and scales to determine the longitude of the sun for any given day. There were other scales depending on the manufacturer's decision. Almost all European astrolabes and many Islamic ones had a scale to solve simple problems of trigonometry (the so-called shadow square). A cotangent scale exists on many Islamic astrolabes to determine the correct prayer time. Islamic instruments may also contain a scale to find the direction to Mecca (Quibla), mathematical scales for sine and cosine or astrological information. European instruments often had a scale for conversions between unequal and equal hours (see explanation below, document for download). The back of all astrolabes has an alidade (dioptre, i.e. a sighting device for taking bearings) to measure the altitude of celestial bodies.