Getting to know the ASTROLABE !

This is how an astrolabe looks like !

 An astrolabe is a very ancient astronomical computer for solving problems relating to time (what time is it ?) and the position of the Sun and stars in the sky.  

Astrolabes are used to show how the sky looks at a specific place at a given time. 

Parts of an Astrolabe

The Mater

The Mater is the main part of the astrolabe; all the other parts connect to it. 

The Plates or Climates

An astrolabe is a very precise instrument, but its accuracy is tied to a specific latitude 

because the projection of the visible sky changes with the viewer’s latitude.

The Rete

The Rete is a cutout overlay that rests on top of the plates. It shows the projection of the 

celestial sphere. Unlike the plates, the rete is designed to turn freely.

The Rule

The Rule rests on top of the rete, and is designed to turn freely. It is used as a pointer during 

calculations and, depending on the origin of the astrolabe and the preference of the maker or 

owner, might be double or single ended; or not be present at all.

The Alidade

On the opposite side of the astrolabe from the rule is the alidade. This is a double-ended 

rotating pointer arm with a set of attached sights for taking accurate angle measurements.

Pin 

Tying together the rest of the parts and providing a pivot point for the rotating parts, the pin 

is placed through the center of the mater.

Mariner's Astrolabe

How to Use an Astrolabe?

Uses:

-- Finding the time during the day or night

-- Finding the time of a celestial event such as sunrise or sunset

-- Finding Latitude of user's location

-- As a handy reference of celestial positions

-- Mariner's astrolabe was widely used as a navigational device

-- Islamic prayer times are astronomically determined

-- Casting Horoscopes

--And many others

In the 10th century, Abd al-Rahmân b. Umar al-Sufī (d. A.H. 376/A.D. 986-7) wrote a detailed treatise on the astrolabe consisting of 386 chapters in which he described 1000 uses for the astrolabe. al-Sufī perhaps overstated the flexibility of the astrolabe, but astrolabes can be used to solve many astronomical problems that would otherwise require rather sophisticated mathematics.