<p>I recently read the relevant parts of the Cambridge Concise History of Astronomy and I'd suggest it was partly good observation, partly luck.</p>

<p>Good observation in that Thales would have noted that the movements of the Sun and Moon were such that eclipses were possible on certain dates, and luck in that the shadow of the eclipse he suggested was possible passed over him or those to whom he had suggested the eclipse took place.</p>

<p>I very much doubt he had the observational data (about the size of the Earth for instance) to have been precise about the shadow path - but would have had the data to show when the Sun and Moon were in alignment.</p>

CC BY-SA 3.0
2014-07-04T14:51:12.423Z
2014-07-04T14:51:12.423Z
adrianmcmenamin
<p>Lunar cycles were known at the time, but not eclipse cycles. Those were only discovered a few centuries later—it’s not obvious if it’s by the Greeks or by the Babylonians. One way or another, it is reasonable to say that Thales could <em>not</em> have guessed that there would be an eclipse at a given time—except maybe in a <em>year</em> and not to a precise <em>day</em>.</p>
<p>The situation has been detailed by <a href="https://ui.adsabs.harvard.edu/abs/1994JHA....25..275P/abstract" rel="nofollow noreferrer">Panchenko 1994</a>. While his conclusion that Thales predicted an eclipse in 582 BCE instead of 585 or 584 BCE is doubtful, he does raise a few issues that make it unlikely that Thales really did predict an eclipse, and that the tale may have been “embellished” by historians, even back then.</p>

CC BY-SA 4.0
2023-06-15T08:50:37.307Z
Thank you for your response. I look forward to reading Panchenko.
David H
CC BY-SA 4.0
2023-06-15T04:01:13.240Z
2023-06-15T04:01:13.240Z
Pierre Paquette
<p><a href="http://en.wikipedia.org/wiki/Thales" rel="nofollow">Thales of Miletus</a> purportedly <a href="http://en.wikipedia.org/wiki/Eclipse_of_Thales" rel="nofollow">predicted a solar eclipse</a> (most likely the solar eclipse of May 28, 585 BCE). The historicity of Thales' prediction can't be verified with any certainty given the sparsity of written records documenting the pre-Socratic era that have survived to present day. So, putting the historical question of whether or not he did aside, what plausible answers are there to the question of how he <em>could/would</em> have made such a prediction?</p>

<history><solar-eclipse>
How might Thales have predicted a solar eclipse?
David H
# How might Thales have predicted a solar eclipse?

(Asked by: username_0 on 2014-06-12)

[Thales of Miletus](http://en.wikipedia.org/wiki/Thales) purportedly [predicted a solar eclipse](http://en.wikipedia.org/wiki/Eclipse_of_Thales) (most likely the solar eclipse of May 28, 585 BCE). The historicity of Thales' prediction can't be verified with any certainty given the sparsity of written records documenting the pre-Socratic era that have survived to present day. So, putting the historical question of whether or not he did aside, what plausible answers are there to the question of how he *could/would* have made such a prediction?

**Tags:** history, solar-eclipse


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## 2 answers

### Answer by username_1 on 2014-07-04. Score: 2 | Accepted answer

I recently read the relevant parts of the Cambridge Concise History of Astronomy and I'd suggest it was partly good observation, partly luck.

Good observation in that Thales would have noted that the movements of the Sun and Moon were such that eclipses were possible on certain dates, and luck in that the shadow of the eclipse he suggested was possible passed over him or those to whom he had suggested the eclipse took place.

I very much doubt he had the observational data (about the size of the Earth for instance) to have been precise about the shadow path - but would have had the data to show when the Sun and Moon were in alignment.


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### Answer by username_2 on 2023-06-15. Score: 2

Lunar cycles were known at the time, but not eclipse cycles. Those were only discovered a few centuries later—it’s not obvious if it’s by the Greeks or by the Babylonians. One way or another, it is reasonable to say that Thales could *not* have guessed that there would be an eclipse at a given time—except maybe in a *year* and not to a precise *day*.

The situation has been detailed by [Panchenko 1994](https://ui.adsabs.harvard.edu/abs/1994JHA....25..275P/abstract). While his conclusion that Thales predicted an eclipse in 582 BCE instead of 585 or 584 BCE is doubtful, he does raise a few issues that make it unlikely that Thales really did predict an eclipse, and that the tale may have been “embellished” by historians, even back then.

> **Comments:**
> **username_0**: Thank you for your response. I look forward to reading Panchenko.  

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