• diameter: 4,5 cm,
  
  
• made of solid brass
  
  
• keychain estrolabe is fully functional
  
  
• information booklet included
  
  
• packed in elegant box

The astrolabe is an ancient astronomical instrument. One of the most amazing and mysterious instruments ever made.

We may even say that the astrolabe is one of the earliest analogue computers. In the past, with help of astrolabe, people could solve problems of:

• astronomy
• cartography
• navigation
• astrology
• geodesy
• cartography
• and many others
  

Astrolabes can be used to solve many problems that would otherwise require rather sophisticated mathematics. For example the instrument can be used for finding the time during the day or night, finding the time of a celestial event such as sunrise or sunset and as a handy reference of celestial positions. When you understand the way it works the range of problems you can solve using the astrolabe is unlimited.

We know several types of astrolabes but the most popular type is the planispheric astrolabe, on which the celestial sphere is projected onto the plane of the equator. This is the type of astrolabe we offer.

The history of the astrolabe begins more than two thousand years ago. The basic principles of the stereographic projection (the way of projection used to prepare the  flat picture of the sky),  were known to Hipparch before 150 B.C.  Witruwiusz, the Roman architect, in A.D. 27, in his book "" described the specific kind of a sundial where this kind of projection was used. The detailed teoretical description of "stereographic pjojection" we may find in Ptolemy work " Planisphaerium "  from A.D. 160.

First true astrolabes (with all basic parts: tympanum, alidade and rete ) were made before A.D. 400. The astrolabe was highly developed in the Islamic world, to flourish in 800-900. The astrolabe was introduced to Europe from Islamic Spain (Andalusia), and since 10th century started to spread, with exeptional speed (impact ?) all  over the medieval Europe.  It was the most popular astronomical instrument until about 1650, when it was replaced by more specialized and accurate instruments.

Astrolabes are still appreciated for their unique capabilites, their value for astronomy education and their beauty when used decoratively.

Customer Reviews:

Peter S.,  Germany
Rating:
I have been interested in astronomy for long time. With great pleasure I visited your website where I found a lot of repilcas of ancient instruments. I bought an astrolabe keychain and i'm pleased with it. I was happy with the service from this online shop and would recommend it to everyone.