Astrolabe Brass astrolabe from the middle ages The astrolabe consists of circles marked with angular measurements By aligning the astrolabe with the horizon the angular heights altitudes and positions azimuths of stars in the sky could be measured An astronomer who knew his location on the Earth could by measuring the position of a standard star calculate the time Astrolabes were widely used in astronomy and astrology and were one of the most important scientific instruments of the time Photograph of an Islamic astrolabe from the period Arab scholars were at this time amongst the most scientificallyadvanced people in the world
