Today we can predict lunar/solar eclipses down to the precision of seconds.[1]

But what was the precision like in medieval times? I imagine it must have improved over centuries. To keep the question very specific I'm looking for the precision in prediction of lunar eclipse around the time of Columbus. But if a broad overview of historical development can be given, it'd be very helpful.

Background: Christopher Columbus used the knowledge of an upcoming lunar eclipse to threaten the local tribes against his God's fury. I was wondering if they all knew exactly how long to wait for the event or they just knew the date on which it'd happen but not the precise time.


1 Answer 1


First of all there is a big difference between solar and Lunar eclipses. (Lunar eclipses are easy to predict, while solar are difficult). Second, there was no much improvement in the medieval period. Development in astronomy was very slow in the countries of Islam, and non-existent in the West between the time of Ptolemy (2nd century) and 16 century. (In the period 2-13 centuries there was even a regress). Third, even the tools of measuring time precisely did not exist. During all this period, Lunar eclipses could be predicted within few hours precision (as Columbus did), but Solar ones could not be reliably predicted.

The difference is that Lunar eclipses occur at a prescribed time everywhere, while Solar ones only in a small area on the Earth, and the time depends on where you are located. So the best one could say is that a solar eclipse "may occur" on certain date.

Both predictions depend mainly on the theory of Moon motion, and the first real improvement of this theory, which had practical implications, after Ptolemy, was due to Tycho Brahe.


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