Oldest recorded solar eclipse helps date the Egyptian pharaohs | Hacker News Reader

Oldest recorded solar eclipse helps date the Egyptian pharaohs

cam.ac.uk

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The paper is available (in HTML even) and much better: https://academic.oup.com/astrogeo/article/58/5/5.39/4159289/...

Who says they didn’t get eye damage from it? Also, I have a feeling most people I know have looked at the sun unprotected for at least some small period of time (including myself) and our eyes seem ok for now.

The human visual system has pain receptors that respond when the eye is overexposed to the visible light portion of the electro-magnetic spectrum. It does not have pain receptors for UV and IR radiation. During a solar eclipse the visible spectrum is reduced below the level at which it will cause permanent damage. Near IR and UV are not, so it is easier to damage one's eyes without experiencing pain.

I used to try to stare at the sun when I was little. It would blot itself out in less than a second with this squishy shimmery black spot (presumably retinal fatigue). It was hard to keep that spot in one place (saccades) though so I would keep chasing it around the sun.

Im mildly myopic with astigmatism, but no abnormal blind spots afaik.

Your brain is really, really good at filling in blind spots. There is a big one where your optic nerve connects to the back of your eye, you can even see it yourself. http://pbskids.org/zoom/activities/sci/blindspot.html

In order to keep from overwhelming the brain with irrelevant optical data, there is a lot of processing going on, and one of the things that happens is a filling in of places where there's no stimulus coming from that part of the eye. It's possible you have blind spots and don't know it. Also, only UV-blocking sunglasses will keep you from getting cataracts.

Because you didn't look at it during an eclipse, when its more dangerous than looking at it on a regular day.

Looking at the Sun for exactly the same period of time is less dangerous during an eclipse because a sizable percentage of the radiation, but not all, is blocked by the Moon.

Where the danger comes in is that normally the Sun is so bright that if you mistakenly look into it your natural reflexes cause you to flinch away, prevent anything more than a momentary glimpse lasting fractions of a second.

During an eclipse the Sun is dim enough that you could stare at it without "visual pain" (for lack of a better term -- whatever you call something that is too bright) to such a degree as to cause instinctual look-away reflexes.

As a result if you were dumb enough, ignorant enough, or presidential enough, you could stare straight at the eclipse for seconds or 10's of seconds during totality. During that time it will not seem "too bright", but nevertheless your eyes will be focusing intensely damaging UV radiation onto your cornea, causing those cells to malfunction and die, which is what causes blindness.

That said, this is highly educated, rational crowd. I would not feel comfortable giving this explanation to a gathering of the general public because it can easily be misconstrued to mean "this guy says looking at the Sun during the eclipse is not as dangerous as everyone says it is" which has the exact opposite implication with respect to safety. I expect this is why the "looking at the Sun during an eclipse is more dangerous" meme got started -- it results in better safety.

All the sources I know of [e.g. 1] say there is no danger looking at the "sun" during 100% totality, and I have stared at the corona for minutes each of all three times I have been fortunate enough to experience totality and I appear to have no visual damage (actually have been tested for unrelated reasons). Of course it is dangerous to look at the sun during the build up to totality - but I recommend not looking up until the corona appears anyway (shadow bands and the onrushing shadow are more exciting than Bailey's Beads).

If you have any reason to believe otherwise please share your sources.

[1] https://eclipse.gsfc.nasa.gov/SEhelp/safety2.html

They're saying this was an annular eclipse, not a total eclipse. In my opinion that would be dangerous to stare at, and I'd suggest the burden of proof would be on you if you disagree.

Yes, an annular eclipse is dangerous to look at at any time without protection. An annular eclipse by definition never reaches totality, since at maximum eclipse the sun is never 100% obscured. While the linked article discussed an annular eclipse, kobeya's comment makes it sound like looking directly at the sun during a total solar eclipse at toatlity is dangerous. This is wrong. It is not.

Don't your pupils shrink dramatically when looking at the bare sun? Whereas they are quite open during a partial eclipse?

> As a result if you were dumb enough, ignorant enough, or presidential enough, you could stare straight at the eclipse for seconds or 10's of seconds during totality. During that time it will not seem "too bright", but nevertheless your eyes will be focusing intensely damaging UV radiation onto your cornea, causing those cells to malfunction and die, which is what causes blindness.

What you are saying is wrong during totality on a total solar eclipse (not an annular one). Your reference to Trump does not apply since he was not in the zone of totality. Did you view the August 21, 2017 eclipse in the zone of totality with glasses on? If so, I feel very sorry for you, you saw nothing.

"When the eclipse is TOTAL, that is, when ALL of it is COMPLETELY covered by the moon, you can then look at it directly without eye protection. In fact, during those few brief minutes and seconds of totality, you MUST look at it without protection to see anything at all."

http://www.eclipse2017.org/2017/viewing.htm

I didn't use the word 'totality' in my comment at all.

Yes, you did. It's the last word of the first sentence I quoted from you. Or the last word of the first sentence of your 4th paragraph.

Why is the light reduced by a huge amount during an eclipse but the UV is still at dangerous levels?

As I understand it, the relevant factors are the brightness per unit solid angle (aka surface brightness), the aperture (area of your pupil). The degree of danger for a given time spent starting at the sun is proportional to the product.

The surface brightness of the sun is the same during a partial eclipse: each bit of sun is just as bright as if there was no eclipse -- there's just less of the sun visible. This is true in visible and UV, so the ratio of UV to visible light is unchanged. The problem is that everything gets darker, so your eyes dilate, which increases the danger. Also, partial eclipses are neat, so you're more likely to stare.

During totality, it's a whole different ballgame. You can't see the bright part of the sun, and all that's left has much less surface brightness. I think it's roughly comparable to the moon.

There's no appreciable wavelength-specific filtering going on in an eclipse since the moon has no atmosphere. (The corona does have a different spectra than the surface of the sun, but that's not the issue here. The corona is dim enough to look at.)

The problem is that there is so much invisible energy in proportion to visible energy. So blocking a large portion of the sun's disk, so your eyes no longer detect too much visible light, still allows too much total energy which fries your retina when focused into a very small area by your eye's lens.

Because the moon is in front of the sun. The brightness is reduced during partial coverage to the point that you won't reflexively look away anymore, but the UV is still there and still causes eye damage.

So why am I being downvoted for answering a question, exactly?

I didn't downvote you, but the reason some did is probably because we want to know why the UV is still there.

Merely restating that the UV is still there contributes nothing.

It's only more dangerous because of the potential lack of discomfort/pain and subsequent reflex to look away; in terms of time you can safely spend looking there is no difference.

I think it's more dangerous to look at the sun on a regular day, It's just more tempting to look during an eclipse.

I don't follow their reasoning. Given their premises:

1. The solar eclipse of Oct 30, 1207 BC is recorded in the book of Joshua, describing events concerning the people of Israel in Canaan (specifically, a battle with some Canaanites).

2. A battle between Israel and Egypt (under Pharaoh Merneptah, son of Ramesses II) is recorded on the Merneptah Stele (which says it was recorded in Merneptah's 5th year).

The researchers conclude:

> So the Israelites must have been in Canaan by Merneptah's fifth year.

> ...

> The confrontation with Israel probably occurred in his year 2 to 4 (Kitchen 2006), so 1207 BC is probably year 2, 3 or 4 of Merneptah.

Huh? They must have been in Canaan by 1207, sure, but why does that imply the Israel/Egypt battle happened in 1207? It seems like 1207 is just an earliest-possible date for the battle...

From what I can tell, the Merneptah Stele has no other information indicating it should be linked to the eclipse or the account from Joshua.

Have I just missed something?

Moreover, the words from Joshua 10:12-13 in Young's Literal Translation (YLT) are:

"Then speaketh Joshua to Jehovah in the day of Jehovah's giving up the Amorites before the sons of Israel, and he saith, before the eyes of Israel, `Sun -- in Gibeon stand still; and moon -- in the valley of Ajalon;'

and the sun standeth still, and the moon hath stood -- till the nation taketh vengeance [on] its enemies; is it not written on the Book of the Upright, `and the sun standeth in the midst of the heavens, and hath not hasted to go in -- as a perfect day?'"

The literal translation is important to see what is actually written in the Hebrew original. It's definitely not the same as the new (too convenient) translation that the paper used:

“And the Sun stood still, and the Moon stopped [Hebrew 'amad], until the nation took vengeance on their enemies,” (Joshua 10:12–13, New Revised Standard Version [NRSV]).

Note that the literal translation gives the positions of the Sun and Moon and they are not on the same place when the event happens. Also note that no eclipse can last "till the nation taketh vengeance [on] its enemies."

Still, it seems to be a one day event, the Ortodox Jewish Bible translates 10:13 as:

"And the shemesh stood still, the yarei’ach stopped, until the Goy had avenged themselves upon their enemies. Is not this written in the Sefer HaYasher? So the shemesh stood still in the middle of Shomayim, and hastened not to go down about a yom tamim (whole day)."

Yom is "day." תָּמִים is indeed elsewhere translated as "perfect" but the meaning of "whole" (complete) in this case really has sense: http://biblehub.com/hebrew/8549.htm

Still doesn't match a description of an eclipse.

... That's the claim of an eclipse in Joshua? It's baloney.

I've seen a total eclipse in person. The most dramatic part of it, which doesn't seem to come out in most modern accounts, is the speed and intensity of what happens when totality happens: 98% coverage is much tamer than than 100%. The temperature drops by several degrees--it feels like at least 10°F--and the sky goes from "it feels cloudy" to "it's dusk except I see light in all directions."

For someone in a pre-Axial Age religion (such as then-contemporary Judaism), which makes a heavy theme out of the idea that humans need to perform rituals to literally keep the universe going, the first thoughts are going to be "how did we screw up?" and even after things return to normal, it's likely to still leave people with the impression that they narrowly avoided the end of the universe.

It's difficult to see even a liberal priest making rhetorical flourishes to older traditions converting an eclipse to that kind of depiction. The text pretty much has a running theme of "gee, it would be nice if the day were longer so I could finish slaughtering my enemies;" eclipses (even if not total) are notable for their very distinct darkening of the sky. The text also emphasizes that the sun and moon stand still, yet an eclipse is one of the few times where you can clearly observe the sun and the moon moving against each other, where you can see clear motion in real time. It's also worth pointing out that the text also says "nothing like this has ever happened before or since." This part of the Hebrew bible is suspected of being written somewhere in the 600s BC, which is more than enough time for other accounts of eclipses to filter through.

Ring of fire eclipses, which is what this one was, are very different. The sky doesn't get dark. The temperature doesn't drop. Birds don't go crazy.

Added to the fact that the events of Joshua are likely completely ahistorical.

They think the battles are the same. The book of Joshua doesn't say they fought Canaanites, just that they fought "their enemies". The theory is that the Egyptians were the enemies.

It does say they fought Canaanites. It specifies that they were Amorites, and names the cities.

Names for enemies weren't always exact and rather name general directions of the wind instead of particular tribes. From the dead sea, canaan and egypt seem close enough to be confused.

Unless you think those Canaanite cities were in Egypt, I'd say the details are given pretty precisely. The book is actually online; you can easily check that there's no chance this was talking about Egypt.

The Merneptah Stele says Israel was wiped out. So it's a pretty tenuous explanation to say that this is the battle recorded in the book of Joshua. Also the book of Joshua says the battle was against the Amorites, that the sun delayed going down for a full day, and that Israel was victorious.

I think it is fair to say the majority scholarly opinion (biblical minimalist or maximalist) is going to consider this theory the work of cranks.

The maximalists don't get their way without a fairly extensive revision of Egyptian chronology, a la David Rohl [1]. The minimalists consider the record of the conquest of Canaan by Joshua to be completely ahistorical.

[1] https://en.wikipedia.org/wiki/New_Chronology_(Rohl)

The Egyptians wrote their military chronicles before they left, foretelling their victories. It's very well possible they said they were going to win and didn't.

Truth in military reporting was probably as common then as it is today.

A bit OT but how did ancient civilizations know that they should NOT watch an eclipse with a naked eye? The knowledge would have been lost or unavailable at each occurence. Remote areas would probably never get the word. So how didn't they get massive eye damages back then?

The same way any civilisation 'knows' anything - speculatively, one guy stares for too long, gets permanent blotches in his vision, tells his friends not to do the same... word gets around, and as far as basic reasoning capacity goes, we're no different from Neolithic hunter-gatherers, even if they might have been more inclined to rationalise it as "the sun-god cursed my eyes for gazing too long at his radiance" than "the intense light scarred my retinas".

Like most dangers communicated to people in the modern world, the danger of looking at the sun is way overblown. You can look at the sun for over a minute straight without any damage. How much damage, how fast, what kind of damage, and how this varies with peoples genetics is not well known, of course. Doing such experiments would harm peoples eyes. How long can you look at a little bit of the sun right around the total eclipse? Very not known. But "safety first" and you get things like and emergency warning sent out to all cell phones before the eclipse saying not to look at the sun. Looking at the bright sun is not a pleasant sensation. I imagine people in ancient times were more in-tune with their physical senses and were less likely to do things that hurt them just for curiosity sake.

"What kind of damage" is pretty well-known.

See e.g. "Light-Induced Damage to the Retina" http://photobiology.info/Rozanowska.html

You are right. Many experiments on animal eyes are highly likely to translate well to human eyes.

With a little more thought maybe all these warnings exaggerating the dangers of the sun to your eyes are a good idea. It seems that humans know or learn "Don't stare into the sun" is a good idea but during an eclipse some people forget that.

Well, we can assume that they knew not to look directly at the Sun on a normal day, right? So there was perhaps already an understanding that caution was warranted.

But how do you know they didn't get eye damage? Seems reasonable to think that people did sustain damage to varying degrees. It still happens today... not even that rare, actually.

Also, assuming they weren't running for cover due to mistaking a total solar eclipse as a bad omen, they may have been interested in other things that prevented them from staring for extended periods. The 360 degree sunset, for example.

Ever seen an eclipse? It generally not obvious that it's happening until just before totality and it's fine to look at during totality. Generally when people go blind watching an eclipse, it's because they knew it was coming and wanted to watch it happen. So a lot of folks probably didn't even think to look up until it was safe to do so.

I wonder if there's any documentation of great panics around these.

I'd imagine the people of the time would think this was some sort of negative sign from their sun god (Horus) and madly prostrate or panic. I think it'd be abnormal for people to stare it as they'd be too afraid but that's just conjecture.

Did you never stare straight at the sun as a kid?

Note that sea captains in the age of the sextant were typically blind in one eye by using the sextant on the one star visible during the day (our sun). But this wasn't from a single viewing, it was from many many viewings, presumably the majority of which were while they were midshipman. They were smart enough to sacrifice one eye, covering the other while looking at the sun.

Nevertheless it's a bad idea, especially with both eyes, and eclipses are more dangerous.

Seems like it would have been trivial to put a filter in front of the upper mirror of a sextant during daylight hours to avoid this. I know that the sextant was an optical device that became commonly used after Newton's Opticks was published, and that Newton temporarily blinded himself while researching it, so there might have been an inkling among the educated that staring directly at the sun was dangerous. But I don't know whether optical filters were known then, or came into use later, as adjuncts to photography. It's definitely too soon for arc welding.

> A bit OT but how did ancient civilizations know that they should NOT watch an eclipse with a naked eye?

Doesn't it hurt when you look at the sun? Any time I've ever accidentally glanced at the sun it's literally a blinding pain and my eyes just close reflexively.

It has never made sense to me when people say, "Don't stare at the sun". It's roughly the same as saying, "Don't stick your hand in the fire." Well duh, it hurts.

Back when I was a kid I used to stare at the sun fairly often, you look at it long enough and you get this sort of shimmering blueness over the bright area and it's no real issue to keep looking at it.

Used to do that during long car trips to pass the time, I don't have any issues with my sight as an adult but it's definitely a necessary warning.

Almost all the stories I have heard of people getting eye damage from staring at the sun have been people on drugs. Usually, the intense pain causes you to look away.

> A bit OT but how did ancient civilizations know that they should NOT watch an eclipse with a naked eye?

How does your civilization know NOT to watch an eclipse with a naked eye?

I’ve seen two total eclipses and one annular eclipse. You wouldn’t even notice an annular eclipse if you weren’t looking for it. I’m not sure how this would have helped Joshua or have been worthy of note.

Historically the stars and sun played a MUCH greater importance than today. They absolutely would have seen and recorded this event. Reason why is we see it in many other recording of them and throughout the ancient world. This helped us to much more accurately date history.

I've seen one total and one annular. Though an annular eclipse is not nearly as dramatic, I imagine a person outdoors a few thousand years ago would have noticed it. It looks as if it is sunset (golden hour type colors) and shadows look strange with a donut pattern.

You'd think they'd have a way of describing the sun being slightly dimmer, like it being a sunset, that's different from 'it completely stopped', since the sun regularly sets.

The "color" of an eclipse, even a partial or annular one, is completely different from a sunset. Sunsets have a "reddish hue" to them.

During an eclipse, the world gets darker without getting redder. Its most dramatic on a total eclipse of course, but even at 80% to 90% it was a different feel than "sunset". Anyone who is outside regularly in a 80%+ eclipse on a clear and open day will notice the dramatic shift in color.

The key is that you'd have to be standing around and getting used to the colors outside to notice.

Yeah, but wouldn’t have made the history books or affected an army. A total eclipse on the other hand would have been a show stopper ... especially in ancient battle.

Turns out such a thing really did happen: https://en.wikipedia.org/wiki/Battle_of_the_Eclipse

... in this case, the eclipse led to the battle being canceled in favor of a peace treaty, out of fear of divine rage.

Dan Carlin covers it in King of Kings (his history of ancient Persia), which is a great listen.

> Yeah, but wouldn’t have made the history books or affected an army.

I can't believe that nobody wouldn't at least jot down, "Dear diary, today a huge fucking chunk of the sun was missing for about an hour. I sure am glad I'm literate, and that the godkingpharaohboss decided that a chunk of the sun missing warranted a brief note on precious lambskin/temple wall/holy book margin."

You can't tell any part of the sun isn't visible by looking at it directly without some sort of shielding from the glare.

You can tell because every shadow will show the weird shape of the sun. Here is a photograph of the shadows during an annular eclipse:

https://imgur.com/gallery/8c7rdEU

Whether or not people >1000 years ago would notice this and record it... I refrain from pretending to know.

It's not smart nor clever, but as a child I used to stare at the sun wide-eyed until my eyeballs teared up beyond my ability to keep them open any longer — easily thirty seconds and more.

My memory was of the sun itself distinctly resolving itself into a perfect circle with a sort of contrasting peripheral shadow that I recall describing as being 'like an aspirin pill'.

I blame some 80s TV show where an astronaut gained superhuman powers of some sort after staring directly at the sun.

I've always been curious to know what, if any, affect this has had on my vision (I don't have a terribly good capacity for resolving contrast during twilight).

I don't have a terribly good capacity for resolving contrast during twilight

Try vitamine A. The effect is very noticeable.

In addition to the shadows, a cloud passing over in about a 2 hour window would make it apparent.

> You wouldn’t even notice an annular eclipse if you weren’t looking for it.

What? The partial eclipse I saw in 2017 was easily noticeable by anyone who looked even remotely near the sun.

To be fair, partial and annular eclipses are noticeable if you are looking for them, but they are absolutely nothing like a total eclipse, which really would feel like something apocalyptic if you were to experience it by surprise without understanding of what you were seeing or knowledge that it was temporary.

Yeah, there's definitely a huge difference between those two and a total eclipse but the assertion keeps coming up that ancient peoples wouldn't notice unless it was a total eclipse which is ridiculous.

You notice it is slightly darker. Most folks aren’t looking at the sun. It surely wouldn’t affect an army.

Tactically yes it being a little dimmer doesn't directly weaken or strengthen a particular army. What is can do is affect morale given that events like this were shocking and often recorded as some kind of ill omen by people that saw them.

I saw the same eclipse in the zone of totality and I'm not sure I agree with you. You noticed something (a little less bright, a little colder) but only because you were expecting it. If you were not expecting the sun to do something unusual I think you'd either just not notice or put it down to some thin cloud cover moving over the sun. I say this because when viewing the total eclipse, things were pretty much normal, albeit a bit less than regular full sun brightness and temperature, until minutes before the onset of totality, so 95+% coverage.

It gets slightly darker, as if it's a bit overcast, but the effect is very subtle due to the logarithmic response of the eye. And it doesn't help to look at the sun because it's much too bright to see the shape.

> I’m not sure how this would have helped Joshua...

Especially when the text goes on to say that the sun "hasted not to go down about a whole day" during which time Joshua defeated his enemies [0]. The article does not address this part of the verse. It also omits the subsequent statement that "And there was no day like that before it or after it..." [1].

[0] https://www.blueletterbible.org/kjv/jos/10/13/t_conc_197013 [1] https://www.blueletterbible.org/kjv/jos/10/13/t_conc_197014

You are forgetting the case of when the sun is behind light clouds (which is not everywhere, but definitely does happen):

http://slideviewer.appspot.com/show?tag=dgay,solar-eclipse,1...

(no filter)

Perhaps that depends on how large of a ring is around the moon? The sun was noticeably eclipsed to the naked eye during the annular eclipse I've seen (2012 in California).

It is quite uncontroversial nowadays in studies of the biblical texts to accept that the book of Joshua (as well many of the other foundational texts) was written in the 7th century BCE. To assume that the writer had any idea what astronomical events happened centuries earlier is implausible.

I used to hate that part of the bible, seemed so obviously wrong. But now I mostly believe it wasn't an eclipse and happened as stated (also Joshua's long day about 50 years later).

TedX talk on the subject: https://www.youtube.com/watch?v=eESlenGhKN0

It's always interesting to see Scientists use the Bible, when much of the western world has described it as fiction. I otherwise, believe it to be non-fiction.

Scientists also look at the old children fairy tales for historical facts[0], but that doesn't make them to be true. The story that has been passed from generation to generation for ages accumulates a lot of secondary knowledge not necessarily related to the primary topic.

0. http://www.sciencemag.org/news/2016/04/some-fairy-tales-may-...

You're conflating the theology of the Bible with the history of the Bible. A (non-believing) scientist/historian might very well decline that Jesus has any supernatural connection, but agree that it is plausible that he was an actual person, born of non-supernatural causes, and had his story confused through time.

I have read theories that God and the Angels just happened to be an race/community of people that impressed those who met them by their size, prowess, or their artifacts, and told their story. This sounds entirely plausible to me as an explanation for the existence of some earthly being who either became or actually was named God.

Similarly, I have read of the supposed existence of ancient birthing/funeral rituals whereby the spirit of one individual is tranferred into the body of another. I can completely rationalise this as an explanation for how Methuselah and his peers were able to 'live' as long as they did.

Though I no longer remember the book I read these things from, and I do not claim that they are scientifically or historically accurate, I think it is a mistake for anyone to suggest that the Bible does not have some historical importance distinct from religion when the correct context is applied.

I am not sure whether this is the same non-fiction you refer to.

>> how Methuselah and his peers were able to 'live' as long as they did

Another possible explanation is that ancient Jews used "Moon years" aka months as unit of measurement :) Then Methuselah's 969 "years" would translate to 80 years, 9 months.

When looking at ancient texts, there's a continuum between "fiction" and "documentary". The biblical texts are not fiction in the same way that, say, Harry Potter is fiction, but they are also not very accurate documents and in the way that Will Durrant's The Story of Civilization is a documentary work. You need to read the bible much more critically if you want to use it to learn about history (absolutely fine to read it uncritically if it is an important part of your faith, of course).

“One chance in ten an individual directly experiences a solar eclipse.” Any spot on Earth sees one in four centuries; life expectancy 40 years. However its pretty certain that people would have heard from neigbors who saw one.

Othe eclipses are fairly common. Lunar eclipses are seen everywhere on Earth every couple years; Moon eclipsing a planet every few years. Combining these eclipses with rumors of solar eclipses, ancient skywatchers would predict the Moon would eclipse the Sun sometime.

And Ireland claims an even older eclipse http://www.astronomy.ca/3340eclipse/. Nov 30, 3340 BC.

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