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Chalid Ben Abdulmelik - Wikipedia, the free encyclopedia |
 | | Chalid Ben Abdulmelik was an Arab astronomer of the 9th century. |
 | | Together with Ali Ben Isa in 827, he measured at 35 degrees north geographical latitude, in the valley of the Tigris, the length of a meridian and thus the Earth's circumference, getting a result of 40,248 km (or, according to other sources, 41,436 km). |
 | | The two researchers measured in Arabian ell, and determined the geographical latitudes of the end points they used from the star altitudes in a celestial horizontal coordinate system. |
| en.wikipedia.org /wiki/Chalid_Ben_Abdulmelik (151 words) |
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