I-Astrolabe
![](http://178.128.105.246/content-http-upload.wikimedia.org/wikipedia/commons/thumb/9/9b/Planispherical_astrolabe_mg_7100.jpg/220px-Planispherical_astrolabe_mg_7100.jpg)
I-astrolabe sisixhobo esisebenzisa indawo apho zimikhona iinkwenkwezi okanye ilanga. Yayisetyenziswa ngokusesikweni kwi- navigation ukunceda iintloli nabakhenkethi baselwandle ukuze babone okokuba baphi na kanye. Umgama phakathi komntla nomzantsi we-equator bawufumana ngomlinganiselo womgama ophakathi kwelanga neenkwenkwezi ngaphaya kwe-horizon. Ii-Astronomers zisebenzisa ezinye iintlobo zee- astrolabes, ezidla ngokuba zezinkulu kunezinye.
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.[1][2][3]