Astrolabe : The Famous Astronomical Equipment in the History of Astronomy in Iran

[Fowad]

‏An astrolabe is a historical tool in astronomy which has a lot of uses in locating and predicting the positions of star‪s,planets,sun and etc.Iranian historical astronomers are famous to improve its usage and made it more applicative and also complex!‬
‏,astrolabe ‬was their Starry night software‪!‬It was in the rule of a data collector‪.‬Those patient astronomers then analyze all these datas mathematically to gain a new result‪.‬
‏Most astrolabes are made by 3 or 4 circular metal plates on each other in a way that can be rotated easily and each circle have some signs and points and lines on them which presents our view of night sky‪.‬
‏It was useful for measuring altitude of masses too‪.‬
‏‪Some very famous Iranian astronomers are proud to develop astronomy of that days by this tool,like ‬Abū Rayḥān al-Bīrūnī ‪,‬ Jamshīd al-Kāshī‪,‬Abū al-Wafā' Būzjānī and etc‪.‬
‪ ‬
‏Here we can discuss more about astrolabe‪.‬I also decided to go and visit a very ancient astrolabe which is found in Pariz‪(‬a City in Kerman Province in Iran‪)‬ by archaeologist‪!‬ I will inform you about it as soon as i see it‪ :have a nice day:

1784

[Fowad]

Woooooooow!
My friend sent me some photos of this astrolabe that i told you!It is very interesting!
notice to the lines beneath the first plate!I think they present the hour circles!
This one is a little strange!It doesn't look like the other astrolabes that i've ever seen!
I have put a folder contains more pictures of it!

http://www.4shared.com/file/s9f1PdhW/Astrolabe.html

[Sunrise]

thanks a lot dear Fowad

this Astrolabe is amazing

?Do you know which year it had been made & from what

!it seems to be Zinc

?is it

[Ehsan]

at first:
tank you fowad!
you said that they predicted the astronomical events at a good precision!
so they should had almost correct cosmology for example they should knew that planets are at a circle orbit around sun.
But did they really know that?

[Fowad]

thanks a lot dear Fowad

this Astrolabe is amazing

?Do you know which year it had been made & from what

!it seems to be Zinc

?is it



your welcome dear Sunrise thanks for your note!
I dont know exactly,I should research more about it but i myself thought it might be almost 600 years old but after i spoke to my friend i got that its younger than!
No i think it has been made of copper.




at first:
tank you fowad!
you said that they predicted the astronomical events at a good precision!
so they should had almost correct cosmology for example they should knew that planets are at a circle orbit around sun.
But did they really know that?


your welcome Ehsan thanks to yourself for your supportive action! ;-)
as you know the fountain of the success of understanding the solar system was also these accurate measuring of the location of Planets which the point is that all those datas were gained by the equipments of that time and i think astrolabe is exact enough and sufficient to locate planets exactly. e.g. Jamshid was a person who studied the Reversionary Movements of Planets by them.
But it is still remains a question that why don't they get the facts of solar system even with those accurate datas and it remains unanswered forever i guess!by the way it is not a far optimism that they did it and don't reveal it...!

[Negar Najafi]

This topic has been inactive for a long time.
Let's start again!
See this astrolabe! It's wonderful!
It's wooden and made by Mohammad Bagher Ebrahim Alkhorasani in 1293.
There are Abjad letters on it.

http://www.astroupload.com/uploads/13408727301.jpg (http://www.astroupload.com/uploads/13408727301.jpg)


*source: http://www.aqlibrary.org

[Ehsan]

its remarkable that ancient people could predict planetary motions precisely with an almost wrong cosmology
today we know Ptolemaic explanation of solar system was not correct but even with this incorrect explanation, the astrolabes told them exact location of planets in future!
and we should notice that it was more than 10 centuries ago

Nasir al-din Tusi recorded the planetary motions so exactly and he realized that Ptolemaic model have some inaccuracy

obviously the Astrolabes based on Ptolemaic model, and with a wrong model you will have a wrong prediction . Tusi improved the Ptolemaic model by his invention: Tusi couple. it was a geometrical solution for correcting the planetary motions

you can see a Tusi couple here:
notice to the red line

http://upload.wikimedia.org/wikipedia/commons/b/b4/Tusi-couple.gif


also whit his model he improved the astrolabes structure

his works on astrolabes:


http://upload.wikimedia.org/wikipedia/commons/1/17/Tusi_manus.jpg


Tusi's model was the best model in his time and it helped Copernicus to propose the heliocentric model

[gshahali]

Hello
Seeing this topic, I was encouraged to learn more about astrolabes. I searched the web and found some sites fully dedicated to astrolabes.
Here is the address of one of them which deserves having a look at:
http://www.astrolabes.org/index.htm
It even introduces a software called "the electric astrolabe".
You'd better go and visit the site yourselves.

Good luck