Odyssean eclipse

[Forum Monk]

What observational techniques do you think were unavailable in c.1200BC?

I don’t know, I’m no astronomer. I defer to the authors of the article:
...

Yeah, well apparently the authors have training in physics and astronomy but probably very little knowledge of ancient texts and mythologies. I have no real task believing the events (which really amount to simple observations - only made more complex by the depth of the author's article) were observed in realtime and then later related in oral stories which were well preserved until Homer committed it to posterity.

I don't think it was back-calculated although there is a chance it could have been pure fiction - a lucky coincidence by a clever ancient writer.

[Grumpage]

Forum Monk

With reference to your question and my reply regarding observational techniques available to the ancient Greeks. I previously quoted the authors thus:

As to the data, it is quite improbable, although not entirely
impossible, that it had been observed and noted, preserved through
oral tradition for centuries, and then incorporated into the story by
the Poet. The main argument against this possibility is that the data
we’ve examined requires observations of a high level of sophistication
for the time and place and its precise preservation in oral
tradition.

While I cannot argue against them, on re-reading the article and more fully appreciating that eyeball astronomy is what it is both now and then, I cannot fully agree with them either. The astronomical events described could clearly be seen. I'm not sure now what they mean by a 'high level of sophistication' - unless it is to do with relative positions/movements of extreme subtlety.

The question of observational plausibilty remains. That is, the concurrent nature of these observations being made around the Ithaca event.

[Grumpage]

I hadn't checked for your posting.

[Grumpage]

A quick further comment on your last posting which I didn't spot because I didn't turn to a new page (I won't make that mistake again).

We must agree to differ on the plausibilty of contemporary observations unless those predating the massacre were accurately guessed with hindsight.

Also, while I am aware that folk/Bardic memories can be good I would question that they are so reliable in the detail. In any event, this is a moot point.

[Grumpage]

Unless someone comes back then this will probably be my last posting on this topic.

The authors of the article examined five astronomical conditions around the time of Odysseus’ return to Ithaca:

1. Turning point of Mercury (34 days before eclipse)
2. Position of Pleiades and Boötes (29 days before eclipse)
3. Equinox (11 days before eclipse)
4. Position of Venus (5 days before eclipse)
5. New Moon (day of the eclipse)

This pattern of conditions is met if the date of the eclipse was 16 April 1178 BCE.

Homer’s references to three of the five conditions are certain (2, 4, 5). His references to these are clear and unequivocal. The other conditions are interpretations of ostensibly non-astronomical passages. These are described by the authors of the article as ‘hypothetical’ or ‘conjectural’. Classicists can make a strong case for interpreting them without reference to astronomy.

If the analysis of the data provided by the authors is restricted to what we can be sure of then we are only looking at the New Moon, the position of Venus and the position of Pleiades and Boötes. This makes a big difference. There are 21 dates where the pattern of these conditions are met. If we stretch it a bit to include conditions that are ‘narrowly missed’ (authors words) a further 21 dates can be included.

So, the single date (16 April 1178 BCE) relies upon information that has been interpreted. Many more dates are otherwise available. (The eclipse, which played no part in the analysis except to kick it off in the first place, is itself an interpretation).

This is just one of the problems encountered in this research. I believe there are many more. That’s not a bad thing. The authors have, hopefully, re-invigorated a debate on the many issues raised and for this they should be congratulated.

[Forum Monk]

Also, while I am aware that folk/Bardic memories can be good I would question that they are so reliable in the detail. In any event, this is a moot point.

I would tend to agree with this statement, but over the last year or so, I have seen many cases where details have seemingly been preserved some way some how. Now, I will give you the evidence is somewhart circumstantial. But let's look at the detail in this tale and then make a judgment; is it really possible the details could not survive 2-300 years of retelling.

Now there are two important things, in my view, we most keep in mind. First, there is no knowledge one way or the other, when the tales were written but it is possible some of them were written by the time "Homer" compiled them. Secondly, remember they were poems and poems are inherently robust in surviving retelling. For example, "Mary Had a Little Lamb" has survived around 150 years already, Many of the Mother Goose tales are over 230 years old and some may be much older.


Hermes goes to Ogygia then back again.
Depending on the origin of this verse, the poem could very clearly indicate that Mercury moved toward a given place in the sky and did a retrograde loop.

Many ancient and modern interpreters believe that Ogygia was located in the Ionian Sea or in the Mediterranean Sea. Later interpretations sometimes identify Ogygia and Phaeacia with sunken Atlantis. A long standing tradition begun by Euhemerus in the late Fourth Century B.C.E and supported by Callimachus[3], also endorsed by some Maltese patriots, identifies Ogygia with the island of Gozo, the second largest island in the archipelago.

Some scholars, having examined the work and the geography of Homer, have suggested that Ogygia and Scheria were located in the Atlantic Ocean. Among them were Strabo and Plutarch

It would seem that no matter where you are in greece, Ogygia would be west of you. Actually Mercury will never move across the sky from east to west since it is usually too close to the sun. It would appear in the west after twilight and then in the east prior to dawn. Observing a retrograde movement of Mercury in the western sky is not very common.


Odysseus sets sail from Ogygia, sees Pleiades, Bootes and the Bear is to his left.
This is confirmation Ogygia is to the west, as Odysseus moves east, since the north (Ursa Major) is to his left. Though there may be a narrow time range when Bootes and Pleiades are both visible, it is an annual event.


Athena travels to Sparta
Assuming the reference point is Odysseus' home of Ithaca, Sparta would be in the east. So a reference to Venus in the east.


Poseidon returns from Ethiopia and sinks Odysseus
Ethiopia is south and so this is a supposed reference to the sun crossing the ecliptic from the south which only occurs on the Equinox. Ok, this is obscure for me so I will defer to the authors on this one.


The New Moon.
We probably do not need to discuss this point as a new moon is very common no remarkable allegory would be required to remember it since it is also required for an eclipse.

Now, add to this the eclipse (which the authors did not do) and you have six generalized astronomical events which can potentially occur on a very specific dates. Hence the authors table of correlations.

I agree with you that the various events are interpretations. Perhaps Hermes movements were never intended to convey a real astronomical observation of Mercury. I find it very interesting, they were able to find a real Mercury event (apparent retrograde motion) which correlates with the other events. What are the odds of that?

Obviously the above events are very general in nature. Venus is in the east, mercury is in the west, it is a new moon, mercury does the dipsy-doodle, it is near the equinox. No high level of astronomical skill required as you agree.

Thanks for posting the article Grumpage. It is a very intersting study.

[Grumpage]

Forum Monk

I assumed this topic to be pretty much played out and so I apologise for yet one more query.

If you follow up one of the references (no.16) in the eclipse article it takes you to a site of historical solar eclipses which includes the 1178BCE eclipse:

http://eclipse.gsfc.nasa.gov/SEhistory/SEhistory.html

Click on the link to Google map to get a picture of its track. You will see that this does not match the track given in the article. In fact it misses Ithaca and Cephallonia altogether.

Being an astronomical illiterate I don’t know what to make of this. Either someone has made a mistake or there are good ‘technical’ reasons why these tracks differ. Any suggestions?

[Forum Monk]

There is a factor known as delta time, which accounts for tidal drag and other effects which vary the speed of the earth's rotation over time. the authors mention the delta time value they used and I used the same one to reproduce their results in a previous post. A different delta time results in a different track. I will check another eclipse database I downloaded from NASA several years ago and see if I can find their DT value.

It should be noted, ancient delta times are not known. They are either extrapolated from current measured values or backed into based on historical observations.

[Grumpage]

The delta t value used by Espenak (Nasa website) = 28590.0 seconds

http://eclipse.gsfc.nasa.gov/SEhistory/ ... pr16T.html

Quote from the B & M article (re their own track):

This particular track is shifted northward from the path from Starry Night Pro, where Ithaka and Paliki lie on the northern edge of totality. Delta T for this track as shown, 28,907. From Starry Night Pro: 27,602.7 s. The Five Millenium canon lists 28,590 s for this particular eclipse under the latest revision.

So, the delta t values are:

Starry Night Pro 27,602.7
B & M article 28,907
Espenak 28,590

Do you agree with this?

I presume you used 28,907. Did your track agree with theirs?

What track do you get with 28,590?

Is Espenak's track on the Google map reliable?

Are we now losing the will to live?

[Forum Monk]

I really like that eclipse site you found, Grumpage. The older version I had did not link to google maps. Did you notice if you click on the path, it gives the eclipse time and stats for the location selected? This is nice.

My data was not significantly different (rounding error) and would have shown more or less the same track. Looking closely at the path given by NASA, Ithaca is only 20km outside of the path of totality. That is not much. So you should be able to visualize if the time was offset one way or another faster or slower, the path would shift left or right. How many minutes later would the ecipse have to have occured to shift the path 29+km to the east? I didn't bother to do the math but its probably only a few minutes (10-15?). If you look at the range of DTs you found (good digging by the way) you will see a variance of some 1000-1300 seconds. So say 20 minutes variance.

Given the nature of how historical DTs are derived I would say, close enough for government work and if the Odysseus eclipse if genuinely described in the text, it may be possible to correct the tables based on this historical evidence. (we simply don't know for certain if the eclipse wat 100%, 95%, 80%, etc total from Ithaca, however, and this is one of the problems with relying on old texts for astronomical data.)

[Grumpage]

This is how I see it now:

(i) We know there was an eclipse in 1178 BCE over the Ionian islands.
(ii) The track of the eclipse can be estimated but it will vary according to the mathematical assumptions used.
(iii) The track, once established, is associated with statistical uncertainty that can shift its position a few degrees either way.
(iv) According to the data presented by our two sources the eclipse may or may not have been total over Ithaca.

One objection to the eclipse interpretation of the text is that only one person (the seer) saw it. A total eclipse could hardly have been missed by others present at the time. But anything less than a total eclipse could have gone unnoticed. Magnitudes of, say, 0.8, will probably be missed by most people. Moreover, awareness of a partial is greatly enhanced if the eclipse is expected. The seer could therefore have detected a partial even though no one else did. It seems to me, therefore, that the Homeric passage is more consistent with a partial than a total eclipse.

However, if a total eclipse is demanded by the text (various translations: ‘the sun has perished out of heaven.’, ‘…has been obliterated from the sky.’,’…is blotted out of the sky.’) then current astronomy cannot confirm or deny it. This sounds perhaps over-scrupulous and almost trivial because, after all is said and done, all that is required of Homer (or whoever introduced the ‘eclipse’ passage) is knowledge of some kind of an eclipse occurring in the area. That’s all there is to it. Whither the details.

[Grumpage]

The eclipse that inspired the B&M article was first mentioned by someone called Scoch in the January 1926 issue of The Observatory:

http://articles.adsabs.harvard.edu//ful ... 0.000.html

He found only one solar eclipse (16 April -1178 BCE) that seemed to fit the facts as he saw them: totality, time of day (around midday), historical time frame (-1240 to -1140 BCE).

Our current knowledge puts the following eclipses at Ithaca during the Scoch period:

-1223 March 5, max at 13.04, mag = 0.864
-1208 May 16, max at 11.53, mag = 0.935
-1192 Jan 21, max at 12.45, mag = 0.807
-1178 April 16, max at 12.22, mag = 0.985

Given that there are now no total eclipses would Scoch have gone into print? Somehow the lack of totality takes the edge off the story. But we will never know. His attitude to partials was ambiguous. He mentions one other contender of high magnitude, currently estimated at 0.969, but ruled it out because it occurred too early in the morning. This magnitude suggests he was looking for near totality.

I would argue, however, that a high magnitude partial eclipse is more in keeping with the Homeric account providing it meets the need for the sun being "blotted out" and the strange fact that no one other than the seer saw it. On this basis the Homeric eclipse is unlikely to be the -1178 one as it would almost certainly have been noticed. The -1208 eclipse might also have been noticed. Below 0.90 it becomes much less likely. I would go for -1223 or, preferably, -1192. That puts the fall of Troy at -1202 BCE.

The dates for the Trojan War now must be revised as a matter of urgency.