| | Astronomy - LearnThis.Info Enclyclopedia (Site not responding. Last check: 2007-10-22) |
 | | Although most astronomers incorporate elements of both into their research, because of the different skills involved, most professional astronomers tend to specialize in one or the other. |
| | The late 9th century Islamic astronomer al-Farghani (Abu'l-Abbas Ahmad ibn Muhammad ibn Kathir al-Farghani) wrote extensively on the motion of celestial bodies. |
| | In the late 10th century, a huge observatory was built near Tehran, Iran, by the astronomer al-Khujandi who observed a series of meridian transits of the Sun, which allowed him to calculate the obliquity of the ecliptic. |
| encyclopedia.learnthis.info /a/as/astronomy.html (1440 words) |
