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    Re: 1491 The year China discovered longitude
    From: Frank Reed CT
    Date: 2004 May 9, 13:42 EDT
    Trevor K wrote:
    "Were Chinese eclipse predictions at the time accurate enough for people to know which Full Moon would have an eclipse or did our hypothetical explorers have to sit around, month after month, waiting against the day when the Earth's shadow would cross the Moon's disc?"

    I don't know. But lunar eclipse predictions in the time of Ptolemy, 1300 years earlier, were very good. The position of the Moon could be predicted accurately enough to find the time of an (umbral) eclipse within two or three hours. They could set the "occur/not occur flag" for a given Full Moon probably with 99% accuracy.

    Frank R
    [X] Mystic, Connecticut
    [ ] Chicago, Illinois
       
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