Many mechanical aids to calculation and measurement were being created for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī while in the early eleventh century.[8] The astrolabe was invented within the Hellenistic environment in either the 1st or 2nd hundreds of years BCE https://simonksyek.bloggazzo.com/25896050/top-latest-five-am-urban-news