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Home | cosmolabe | astrolabe | rubulmujayyab


Astrolabe is an instrument used by the Arabs and the rest of world as a computer for nearly five centuries . It is Ptotalamic model of universe portable in hand and was used tofind the possition of the Sun and other major stars at any time of day and night and throughout the year.
1. AL Umm (Mather in Latin)
    It is the main body of the instrument a disc suspended on a ring ,graduated it's limb with degrees and iside the degree circle scale the two dimentional vew of the three dimentional sky from a definit point on earth,marked with azimuth-altitude cordinates as the celestial north pole at it's centre.
2. Ankabooth (Rete in the Latin)
    It is main movable body of the instrument and is a two diomentional picture of the three dimentional celestial sphere marked with the ecliptic,costelations and major navigational stars with their names.
When the ankabooth rotate above the latitude plate (safeeha) it can be read the possitions of stars and other celestial bodies.
3.  Al Idada .
     It is the pointer arm of the instrument used to meassure the angles of celestial bodies.



Rub ul mujayyab is a simple astronomical insrument used by the Arabs for complicated uses. It was used to find the horizontal apparant altitude of celestial objects for a specified time,to find latitudes of any place,and to find solutions of trigonometric probloms. In 15 th century an Egyptian astronomer Jamaludheen Abdulla Maradeeni wrote a book " RISALA FI AMALI RUBUL MUJAYYAB" and mentioned 20 uses of the instrument.
        It is a quarter of a circle made of wood or metal and divided it's arc side into 90 degrees (Qaus) . The lines from both ends of arc to the centre of the circle are called "Jaibs".60 perpencular lines of jaibs are intersecting each other. On the one side of the jaibs there are two cuttings or flaps to use as vewpointers and are called "hadafs"
From a pinhole of the centre of the circle there is chord called "khait" and is used as plumb line and pointer of angles in degree scale.

In Kerala there are many old Masjids and some of them dates bach to the begining of hejara era. They were the cultural centeres of Islam.Allthough Muslims are mostly needed astronomy to fix the starting of months, to tell prayer time and to use other matirial purpuses.
          In the campuses of some Masjids there are some granite pillars which are used to observe the meridian transit of the sun. they are just clearly rectangular stones turned it's edge towards true north with a hole in the centre.When the rays of sun is absolutly not touching the interior is the time of sun's meridian transit and it is the time of dhuhr prayer.
Now these instruments are not using because of the easy instruments to tell time and directions.

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