Tuesday, February 28, 2017

Astrolabe, Ancient Handheld Device

Imagine if you or I were to go back to Ancient times, around the time of the Maccabee's, for a point of reference or the time of Jesus which is more widely known. Then, imagine if you or I were to give any person in either of these settings an iPhone or an iPad. Chances are, they would not have the first clue of what it might be, or how to turn it on, not to mention the countless ways in which it can be used. And then, switch that very scenario to a Maccabee Brother or any person living in Jerusalem in the time of Jesus. If anyone of those people were to hand any one of us an Astrolabe, chances are, we would not have a clue to what it might be, how to 'turn it on', not to mention the countless ways in which it can be used. 
The Whole Astrolabe or the mater, Latin for Mother, is the main body of the Astrolabe. The edge of the mater is called the limb, on which are the degree scale and scale of hours are engraved. The hollowed-out part of the mater is called the womb and contains the latitude plate.

The rete (pronounced, 'reet'), acts as a model of the sky, with the plates lining up behind. The rete is the movable part on which the position of the sun and the stars are depicted.
Display of the rete and the plates, with the mater holding everything together, in the back.
Another view of the display of the Astrolabe parts: rete, plates and mater.
I have been sitting on this post for months now because there is no simple explanation to what an Astrolabe is, how and why it was created and the thousand ways it can be used. I first saw it on display at the 'Jerusalem:1000-1400, Every People Under Heaven' at the Met in New York last October. As I was walking though the exhibit, it was one of the first things which caught my eye. I had no idea what it was. What I did know was that it was very beautiful, looked very interesting, and it 'felt' important. I was also taking pics of the captions, thinking ahead to Instagram and this blog. Thank goodness these pics which I took at the exhibit are good, because the pic for the caption of the Astrolabe was blurry, impossible to know what it said, so, I still had no idea what on earth this was. When I came back to Colorado, I began to dig around to get some answers. I am not sure how I got there, but ohmygoodness, the information was mind boggling.

One great piece of information I found, was that there was a woman, her name was Mariam al Ijliya, a famous astrolabe maker who lived in Aleppo in the 10th century. So hard to imagine, given the images we see today of what was once a diverse and thriving ancient culture. If she could speak, she might say that she was a pioneer of this ancient device, and that it was the GPS of its day!!!! I am guessing none of us could have functioned without an Astrolabe to know the time of day, sunrise, sunset, seasons for planting, directions, celestial events, just to mention a few. I have highlighted the word Astrolabe to link to various sites where I gathered this information.

This is a brief overview of what I learned: 
'The astrolabe is an astronomical calculating device used from ancient times into the eighteenth century. Measuring the height of a star using the back of the instrument, and knowing the latitude, one could find the time of night and the position of other stars. The openwork piece on the front, called the rete, is a star map of the northern sky. Pointers on the rete correspond to stars; the outermost circle is the Tropic of Capricorn, and the circle that is off-center represents the zodiac, the apparent annual motion of the sun. Engraved plates that fit below the rete have scales of altitude and arc of the horizon for specific latitudes.'

 'A typical old astrolabe was made of brass and was about 6 inches (15 cm) in diameter, although much larger and smaller ones were made. Astrolabes are used to show how the sky looks at a specific place at a given time. This is done by drawing the sky on the face of the astrolabe and marking it so positions in the sky are easy to find. To use an astrolabe, you adjust the movable components to a specific date and time. Once set, much of the sky, both visible and invisible, is represented on the face of the instrument. This allows a great many astronomical problems to be solved in a very visual way. Typical uses of the astrolabe include 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. Astrolabes were also one of the basic astronomy education tools in the late Middle Ages. Old instruments were also used for astrological purposes. The typical astrolabe was not a navigational instrument although an instrument called the mariner's astrolabe was widely used in the Renaissance. The mariner's astrolabe is simply a ring marked in degrees for measuring celestial altitudes.'

'The origins of the astrolabe were in classical Greece. Apollonius (ca. 225 BC). The most influential individual on the theory of the astrolabe projection was Hipparchus who was born in Nicaea in Asia Minor (now Iznik in Turkey) about 180 BC but studied and worked on the island of Rhodes. Hipparchus, who also discovered the precession of the equinoxes and was influential in the development of trigonometry, redefined and formalized the projection as a method for solving complex astronomical problems without spherical trigonometry and probably proved its main characteristics. Hipparchus did not invent the astrolabe, but he did refine the projection theory.'

Below is a beautiful, short video of a gifted, dedicated, contemporary Astrolabe maker!!!

 'To him that by wisdom made the heavens: for his mercy endureth for ever.
To him that stretched out the earth above the waters: for his mercy endureth for ever.
To him that made great lights: for his mercy endureth for ever:
 The sun to rule by day: for his mercy endureth for ever:
The moon and stars to rule by night: for his mercy endureth for ever.'   Psalm 136:5-9