Many ancient cultures believed that eclipses are caused by things other than syzygy. The Egyptians had Apophis. The Hindus had Rahu. (The interested reader can see more here.)

In light (ha) of the fact that so many cultures believed in such creatures, I felt compelled to ask: Do Chazal discuss what causes eclipses? Obviously they wouldn’t say there’s a god in charge of eating the sun, but did they know that it was caused by the moon getting in the way of the sun, or the earth getting in the way of the moon?

I am specifically looking for sources in the Gemara or earlier.

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    I don't think you'll find anything in the Gemara or earlier. Remember Greeks knew it was syzygy so it's pretty reasonable that Chazal did too
    – Double AA
    Commented Aug 17, 2017 at 23:34
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    @DoubleAA I figured that by the times of the late Rishonim/early Acharonim who discuss syzygy, that was a well-enough-known phenomenon that it doesn’t prove anything. That’s why I was asking for much earlier sources.
    – DonielF
    Commented Aug 17, 2017 at 23:35
  • related: judaism.stackexchange.com/questions/84291/…
    – Menachem
    Commented Aug 18, 2017 at 1:33
  • If the chachamim didn't believe in syzygy, what did they think caused the molad?
    – DanF
    Commented Aug 18, 2017 at 16:51
  • @DanF Obviously they knew about syzygy. Did they know that a solar eclipse is a special case of a molad?
    – DonielF
    Commented Aug 18, 2017 at 17:31

2 Answers 2


I found discussion of eclipses in the g'mara, but not of the science of them. On Sukkah 29a the g'mara first discusses eclipses as omens (all bad). It then turns to causes:

The Sages taught that on account of four matters the sun is eclipsed: On account of a president of the court who dies and is not eulogized appropriately, and the eclipse is a type of eulogy by Heaven; on account of a betrothed young woman who screamed in the city that she was being raped and there was no one to rescue her; on account of homosexuality; and on account of two brothers whose blood was spilled as one.

And on account of four matters the heavenly lights are eclipsed: On account of forgers of a fraudulent document [pelaster] that is intended to discredit others; on account of testifiers of false testimony; on account of raisers of small domesticated animals in Eretz Yisrael in a settled area; and on account of choppers of good, fruit-producing trees.

According to Chazal, eclipses -- which are bad -- are punishment for certain transgressions. In other words, according to this g'mara they're divinely directed. That doesn't mean they didn't understand that this is accomplished by something moving in front of something else, but it suggests that they didn't know they could be predicted through science.

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    Similar comments appear in Gen. Rab. 10:4, Tos. Suk. 2:6 and Mekh. RY 12:2:4.
    – Argon
    Commented Aug 18, 2017 at 3:26
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    Regarding your last point see further judaism.stackexchange.com/q/16891 - just because it’s a “bad omen” doesn’t mean they didn’t know it was predictable. Saying it’s a time of judgement, as the Aruch LaNer seems to suggest, just means that these are times during which HaShem judges the world for these sins and metes out judgement accordingly - hunger or war, as discussed earlier in that sugya. Or according to the Yearos Devash, it’s not talking about eclipses at all, and therefore it’s no proof. (Personally I find the former more compelling, but who am I to argue on our gedolim?)
    – DonielF
    Commented Aug 18, 2017 at 4:16
  • @Argon Regarding Bereishis Rabbah, are you referring to אין לשון ויכלו אלא לשון מכה? All that Midrash means is that nature used to work a lot faster back in the day. Regarding Tosefta and Mechilta, I believe those are the very Braisos the Gemara is quoting - very good tracking down the originals.
    – DonielF
    Commented Aug 18, 2017 at 4:27
  • @DonielF You are right that Gen. Rab. doesn't discuss eclipses. I only included it because it shows some rabbinical knowledge of orbits.
    – Argon
    Commented Aug 18, 2017 at 21:19
  • @DonielF The sins Rabbis counted were predictable?
    – Al Berko
    Commented Aug 20, 2019 at 12:44

What I heard based on a lecture by Rabbi Yaakov Trump is that he quotes the Aruch LeNer who says that Chazal here is explaining the why behind eclipses, not the how, since science already explains the how.

The lecture can be found on YU Torah here.

  • Avi Kupchik, consider editing in sources and clarify exactly what Rabbi Yaakov Trump said.
    – ezra
    Commented Aug 18, 2017 at 17:43
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    He didn't say if Chazal knew the how or not, just in Sukkah they were discussing the why.
    – robev
    Commented Aug 20, 2017 at 14:44
  • I thought this was a troll post because of the Rabbi's name but it is a real link. Commented Aug 28, 2018 at 2:14

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