Question

It says in Tractate Sukkah (29a): "When the luminaries are eclipsed, it is a bad sign for the world." And: "Because of four things the sun is eclipsed: because of the death of the head of the religious court who is not eulogized properly… And because of four things the luminaries are eclipsed: because of those who write slanderous documents…".
 
And the obvious question is: solar and lunar eclipses are fixed in nature in a deterministic way, and it is possible to calculate in advance when they will occur. How, then, can it be said that they are eclipsed because of the above behaviors, when the phenomenon is necessary and its occurrence can be calculated?
 
With this question it is hard to answer that the Sages of Israel were mistaken and thought that nature was "open," since already in their time the calculation of solar and lunar eclipses was well known among the sages of the nations, as explained in the books, and astronomy was known among the Sages of Israel, who used it for the sanctification of the month (see in this context: Meiri on Shabbat 75a, and in Maimonides, Laws of Sanctification of the New Moon, chapter 17 at the end). It is forced to say that they were mistaken about this.
What, then, is the explanation? How, in your opinion, did the Amoraim understand the above saying? It almost gives the impression that all these sayings are something like a preacher expounding to the masses and stirring them to the service of God—little homiletic lines, not something that should be taken seriously and checked to see whether it really holds up…