I-astrolabe yokuqala yeenziwa kwilizwe le-Hellenistic ngo-150 BC. Isoloko isayanyaniswa ne-Hipparchus. I-astrolabe yayingumtshato we-planisphere (Isixhobo se-compyuting esiyitshathi efana nenkwenkwezi) ne-dioptra (isixhobo sokwenza umlinganiselo we-angles). Kwakuyi-calculator ekwaziyo ukuza nezisombululo kwiintlobo-ntlobo zeengxaki kwi--astronomy. U-Theon wase-Alexandria waabhala incwadi entsokothileyo kwi-astrolabe. U-Lewis uthi u-Ptolemy usebenzise i-astrolabe ukuze enze ouphando relwe-astronomy lube lolushicilelweyo kwi-Tetrabiblos.