Original: Chicago & London : University of Chicago Press 1989 , 14 -- 16 Nevertheless , a Chinese historian of astronomy , Xi Zezong , claimed that the Chinese astronomer Gan De observed one of Jupiter 's moons in 362 BC , nearly 2 millennia earlier than Galileo .
Simplified: Chicago & London : University of Chicago Press 1989 , 14-16 . A Chinese historian of astronomy , Xi Zezong , claims that Chinese astronomer Gan De observed one of Jupiter 's moons in 362 BC , nearly 2 millennia earlier than Galileo .