Astronomical Events During the Time of Epicurus

Quote from Nate

why he suggested that both celestial objects are about the same size.

You're probably right but did he say that precisely, or was it that both were "about the size they appear to be?"

Quote from Nate

so the Sun and the Moon must be immeasurably larger by comparison than a mountain.

YES I think that is a very important point, and for me that seals in my mind that people who assert that he thought the sun to be the size of a basketball, or whatever analogy they use to indicate that Epicurus thought the sun was relatively small, are full of nonsense.

Like I said in the podcast I don't think it's necessary to try to maintain that Epicurus' view of the size of the sun has turned out to be "exactly correct," although i am open to the possibility that the "size that it appears" might even be stretched that far, especially if we could find more of Epicurus' writings on the subject.

But even if we don't maintain that Epicurus was completely right, there's no need at all to ridicule his position as absolutely wrong, at least without noting the point that you are making here that Epicurus surely understood that the Sun is very large.

Quote

"An eclipse of the sun or moon may be due to the extinction of their light, just as within our own experience this is observed to happen ; and again by interposition of something else--whether it be the earth or some other invisible body like it. And thus we must take in conjunction the explanations which agree with one another, and remember that the concurrence of more than one at the same time may not impossibly happen. [He says the same in Book XII. of his "De Natura," and further that the sun is eclipsed when the moon throws her shadow over him, and the moon is eclipsed by the shadow of the earth ; or again, eclipse may be due to the moon's withdrawal, [97] and this is cited by Diogenes the Epicurean in the first book of his "Epilecta."]

So, according to Epicurus (in Herodotus), the moon and sun and Earth don't necessarily interact the way Nate had laid out. So, Epicurus, viewing the eclipse wouldn't necessarily have had to conclude that the sizes of the bodies implied those sizes Nate was referring to. Epicurus had multiple explanations at his disposal.
This still doesn't address "How big did Epicurus think the moon and sun were?" however. Still looking into that.

Quote

"The size of the sun and the remaining stars relatively to us is just as great as it appears.119 [This he states in the eleventh book "On Nature." For, says he, if it had diminished in size on account of the distance, it would much more have diminished its brightness ; for indeed there is no distance more proportionate to this diminution of size than is the distance at which the brightness begins to diminish.] But in itself and actually it may be a little larger or a little smaller, or precisely as great as it is seen to be. For so too fires of which we have experience are seen by sense when we see them at a distance. And every objection brought against this part of the theory will easily be met by anyone who attends to plain facts, as I show in my work On Nature.

Aarrrgh! Those is so frustrating! He's right there! Just tell us how big you think it is! One stadia? The size of a kylix? The height of the Acropolis?? Anything!
We also don't have the volumes of On Nature. I'm sure it's in there buried in a charred scroll still underground in Herculaneum.

It seems clear that he thought it was important to limit the distance on the grounds that (1) light sources don't shrink as much as other objects at a distance and (2) things that we see sharply don't tend to be as far away as objects that seem to us to be blurry.

But on the other hand we see the sun and moon on the horizon as further away or at least comparable in size to the mountain ranges, and we know the mountains to be huge.

I am thinking that part of the answer here lies, as in other areas, in comparing Epicurus to what he was arguing against. I don't have a reference but I seem to have picked up over the years that the people Epicurus was arguing against (Pythagoreans?) had calculated the sun to be huge as part of their program of seeing the sun (and maybe moon and stars) as gods, and so they were using their calculations of the size being hugely bigger than the earth itself as part of their program of deeming the sun to be a god. (Not sure what they thought about the size of the moon. Did they have that right?)

So maybe it would be clearly to us what Epicurus was saying if we knew that he thought it was possible and acceptable that the sun be bigger than the mountains, just so long as he didn't have to admit that the sun was many times larger than the earth itself.

That probably takes us back to the issue of what the model really was. Our world is clearly not the center of the universe, but was the earth the center of our world? If so, then we might have the perspective there that would allow us to see that Epicurus could admit that the sun was pretty large just so long as the calculating didn't have it swallowing up the whole "world." And we could probably come up with a picture or diagram that would make the position a lot more clear, and a lot less ridiculous-looking, than presuming he meant the sun was the size of a basketball.

In fact, a diagram of our "world" in Epicurean terms would be highly helpful for many uses.

I wonder if the Antikythera mechanism, or other Greek diagrams of the solar system (if they exist) would not give us insight into their way of looking at this. Perhaps the diagrams showing the sun to be large, and yet no so large as to swallow up the earth many thousands of times over, would help us get a more balanced picture of the situation.

https://scitechdaily.com/2000-year-old-…first-computer/

As I interpret Lucretius, Epicurus believed that the sun and the moon inhabited the sphere of the air along with the Earth. Encircling that was the ether which held the stars. Lucretius says the sun MAY inflame the air around it which is why it's "small" but so hot. So, it appears to me, that the sun and moon were not seen as similar to the stars and that each (sun/moon then stars) inhabited different parts of our Cosmos. The Earth, sun, and moon were round celestial bodies surrounded by "air." The stars and planets ("wandering" stars) were fires, of some sort, embedded in the ether.

https://www.loc.gov/collections/fi…-and-cosmology/

"By the 5th century B.C., it was widely accepted that the Earth is a sphere. This is a critical point, as there is a widespread misconception that ancient peoples thought the Earth was flat. This was simply not the case."

Plato's cosmology outline

https://faculty.washington.edu/smcohen/320/timaeus.htm

Plus, added bonus: This finally shows me why Epicurus wrote his "The Angles of the Atom." Plato thought atoms only came in 2 triangular shapes! Epicurus and Democritus had many shapes.

Also see section on Hellenistic astronomy here

https://en.wikipedia.org/wiki/Ancient_Greek_astronomy

Great research.

So if this is Aristarchus' model as to the sizes:

What do we think about whether Epicurus was disputing this, or whether is "it is the size it appears to be" can be reconciled with this, which would indicate that the sun is larger than the earth?

It could not have been lost on Epicurus that as formula in words like "it is the size it appears to be" will strike some people as too ambiguous to be useful. So is that phrasing in itself an indication that Epicurus knew very well that the sun was not the size of an orange or any everyday object like people accuse him of believing? Almost certainly he knew that a very large size was a reasonable possibility, and it doesn't appear that he wanted to eliminate that possibility, along the lines of our continuing observation that only one among several alternate possibilities can't be arbitrarily selected as the sole answer.

Maybe that's an easier way to ask the question.

"Does Epicurus' answer allow for the possibility of the Sun being larger than the earth?"

Quote from Nate

It would be uncharacteristic and inconsistent of Epicurus to support this, especially when he posits the explicit existence of exoplanets.

All great points, Eikadistes , but I do want to fine tune your statement quoted here.

What Epicurus posited was an "infinite number of cosmoi (cosmoses?):"

τὴν ἀπειρίαν τῶν κόσμων.

...tēn apeiran tōn cosmon.

We live in a cosmos composed of the Earth at the center with the sun and moon and stars encircling us.

Other cosmoses with their own sun, moon and stars exist according to his theory, but they're their own world-system. They don't inhabit our world-system or cosmos. And the gods live in between these cosmoi in the metacosmia/intermundia. And all those cosmoi are part of the All, Το Παν, To Pan, the Universe.

Sorry to be pedantic, but I don't want to equate our knowledge of exoplanets in our cosmos, as it were, with what Epicurus would have understood that to mean.

What are you guys thinking about this way of asking the question. I think I see your answer, but can this be answered clearly yes or no?

"Does Epicurus' answer allow for the possibility of the Sun being larger than the earth?"

Quote from Cassius

What are you guys thinking about this way of asking the question. I think I see your answer, but can this be answered clearly yes or no?

"Does Epicurus' answer allow for the possibility of the Sun being larger than the earth?"

I think there are multiple possible responses that answer that question. But, if that's the case, I guess the answer to that specific question is yes.

Quote from Nate

cared about it, which I think he did not.

As usual I may or may not be plagiarizing this from DeWitt, but I do think that he would have cared about it to the extent that some people might equate immense size with an attribute of being a god (in the supernatural/non-Epicurean sense). I think I remember reading DeWitt say that, or maybe it was someone else, or maybe I am just dreaming it. There should be no necessary relationship between size and being a supernatural god, but I can see the possibility of enough connection that it might have been on Epicurus' mind as a reason to denounce the conclusions of those who were arguing that their geometric calculations were somehow divine.

(Note - I may be reading it into that passage from Lucian criticizing the mathematicians, which wasn't directly on point, but I think would be related. Let's see if i can find it reasonably quickly. Ok it's here:

from Lucian’s Dialog “Icaromenippus, An Aerial Expedition:”

“Menippus. Ah, but keep your laughter till you have heard something of their pretentious mystifications. To begin with, their feet are on the ground; they are no taller than the rest of us ‘men that walk the earth’; they are no sharper-sighted than their neighbors, some of them purblind, indeed, with age or indolence. And yet they say they can distinguish the limits of the sky, they measure the sun’s circumference, take their walks in the supra-lunar regions, and specify the sizes and shapes of the stars as though they had fallen from them. Often one of them could not tell you correctly the number of miles from Megara to Athens, but has no hesitation about the distance in feet from the sun to the moon. How high the atmosphere is, how deep the sea, how far it is round the earth— they have the figures for all that. Moreover, they have only to draw some circles, arrange a few triangles and squares, add certain complicated spheres, and lo, they have the cubic contents of Heaven.

Then, how reasonable and modest of them, dealing with subjects so debatable, to issue their views without a hint of uncertainty; thus it must be and it shall be; contra gentes they will have it so. They will tell you on oath the sun is a molten mass, the moon inhabited, and the stars water-drinkers, moisture being drawn up by the sun’s rope and bucket and equitably distributed among them.”