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ASTROLABE.
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.
MAIN PARTS OF ASTROLABE.
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
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.
OBSERVATOTIES OF MASJID CAMPUS
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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