Li Fan (Han dynasty)

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Li Fan (Chinese: 李梵, pinyin: Lǐ Fàn) was a Chinese astronomer during the Han Dynasty (202 BC-220 AD).

He noticed that the Moon does not move uniformly through its phases by using background stars as reference.[citation needed] In 85 Li Fan and Bian Xin (Chinese: 編訢) were tasked by Emperor Zhang to resolve inaccuracies in the Taichu calendar.[1][2] He is also known to have worked with inflow clepsydras as opposed to earlier, typically less accurate outflow clepsydras.[3]

The measurements of synodic periods of the planets given in the following table are attributed to him.[4]

Comparison of Li Fan's values for the synodic periods of the planets[4]
Planet True value (days) Li Fan's value (days)
Mercury 115.877 115.881
Venus 583.921 584.024
Mars 779.936 779.532
Jupiter 398.884 398.846
Saturn 378.092 378.059

An impact crater that is located at the Phaethontis quadrangle, Mars, 47.2°S Latitude and 153.2°W Longitude was named in his honor. The diameter of the impact crater is approximately 104.8 km.