Persian astrolabe, 1070AH
This beautiful Persian astrolabe dates from 1659/60 by Western calendars. The Islamic calendar is different from the Western calendar and year one is the year that Prophet Muhammad went from Mecca to Medina. In the Islamic calendar this astrolabe dates from 1070AH.
An astrolabe is like an early pocket computer – it can have many different functions built into it. All have a 'rete’, a moveable web-like plate with pointers. Each pointer is labelled with a different star name, and the rete sits on top of another plate, giving a grid of co-ordinates. Together the rete, the plate and a sighting rule (used to make observations) allow the user to find the time from the stars. Astrolabes can also help find which stars would be overhead at a particular time.
The modern-day descendant of the astrolabe is the planisphere.
The back of each astrolabe could be very different, depending on the skills of the person who made it. On the back of this astrolabe there are several grids.
One grid is for finding the direction of Mecca from a number of different towns and cities; another for telling the time by the Sun and another for finding the heights of buildings. This means the instrument can be used for surveying as well as astronomy.
The astrolabe is covered with text including the name of the maker, a passage from the Qu’ran or Koran (the holy book of Islam) and lines from an early Persian poem. Unusually, one plate on this astrolabe is decorated with constellations.
