And just to clarify, the paper hasn't been accepted yet. It is still to pass peer review, but Climate of the Past is open access, and publish manuscripts online for open discussion while the paper is being peer reviewed by anonymous referees (whose review comments will appear alongside the paper). This in many ways means that it can be effectively be "peer reviewed" by anyone in
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JonnyMcA
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Laboratory
Indeed, there is no requirement that the two occurred at exactly the same time, and the fact that it is said that they do is likely a fabrication. if we do take it at face value though, the statement that the obscuration event occurred after the blinding of the emperor could be many months or years after, but of course people of that time linked the two together. But the point is that there is
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JonnyMcA
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Laboratory
Just published online today for open discussion while it undergoes peer review, is this paper by Mike Baillie and myself, in which we argue that the ice core dating in the 6th and 7th centuries AD (and likely before), are too old by 7 years. We do this by comparing the spacings between frost ring events in American bristlecone pines and spacings between volcanic acidities dates measured by the
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JonnyMcA
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Laboratory
Hermione Wrote:
-------------------------------------------------------
> JonnyMcA Wrote:
> --------------------------------------------------
> -----
>
> > The article she is refering to is this one
> The
> > Neoglacial landscape and human history of
> Glacier
> > Bay, Glacier Bay National Park and Preserve,
> > southeast Alaska USA, the seco
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JonnyMcA
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Laboratory
The article she is refering to is this one The Neoglacial landscape and human history of Glacier Bay, Glacier Bay National Park and Preserve, southeast Alaska USA, the second one on her publication list.
Jonny
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JonnyMcA
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Laboratory
In semi-related news Alaskan trees over 2000 years old uncovered after glacial retreat
<;
Jonny
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JonnyMcA
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Laboratory
Amazing what a good typo can do for the progress of science.
Jonny
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JonnyMcA
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Laboratory
I cant think of anything else fun to waste it on
Jonny
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JonnyMcA
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Laboratory
There was some excitement (to those that find these things exciting!) in 2009 when "monopoles" were observed in so called "spin ices"
These monopoles are not true monopoles though, by which I mean the theoretically possible fundamental particle, which may or may not exist (but the search for which has resulted in insight to other fields such as cosmological expansion).
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JonnyMcA
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Laboratory
Indeed, and the principle is used as a form of magnetic baking in vehicles (called Eddy Current braking) .
The experiment is usually demonstrated to prospective students on university open days, as it is one of those visually accessible things that captures both an individuals attention as well as the the essence of "hidden" physics involved.
Jonny
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JonnyMcA
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Laboratory
I hope it made sense, since re-reading it myself its very badly written (I blame the my kids who were all rather distracting).
Jonny
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JonnyMcA
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Laboratory
Hi Charlie,
The remaining redshifted light comes from purely from the zero point motion of the mirror itself as it is moving away from the laser beam. At zero Kelvin (or close to it in the real world), the mirror still moves forward and backwards (that is towards the laser source, and away from the laser source). Normally as the mirror moves away from the laser source, the reflected light wi
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JonnyMcA
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Laboratory
Here is a great and interesting animation/talk about Quantum Mechanics of macroscopic objects, in particular a recent experiment using "Heisenberg's Microscope".
Note they didnt actually get to zero Kelvin for the experiment, but got the temperature to less than 100 milliKelvin (I think the actual temperature was 25 mK) see press release here and the paper is available here
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JonnyMcA
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Laboratory
I cant comment upon the interpretation of the pictures being night or day. In my view there is no indication that it is day or night, and to be fair, there does not seem to be any indication that the texts as to whether it occurred in daylight or not.
I imagine most battles took place during the day (ignoring night raiding and skirmishes), but wasnt the 776 stuff a siege, which would have bee
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JonnyMcA
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Laboratory
Thanks for reminding me about that post and the illustrations, they are very interesting. I agree with what you say with needing to know more about them, but it does seem that they are depicting something celestial as occurring, and indeed, there is no indication to whether it is occurring during the night or day.
Its hard to say whether the aurora can be visible during daylight, but they co
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JonnyMcA
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Laboratory
Aurora can appear in different forms. What you are thinking of tends to be the ribbon/curtain appearing ones, but they can also appear as sheets of light, or pillars etc. I had a quick look through online images of aurora and this one could be seen as a red shield embedded in the sky (at a stretch).
One thing to bear in mind is that Aurora are not common at mid latitudes, and tend to only
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JonnyMcA
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Laboratory
It is rather likely, since aurora structure does take on the shapes of undulating ribbons that could be seen as serpents.
Also, it can explain the "fiery shields" of Charlemagne. From Anneles Regni Francorum (Royal Frankish Annals) from here
QuoteSed Dei virtus, sicut iustum est, superavit illorum virtutem, et quadam die, cum bellum praeparassent adversus christianos, qui in ip
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JonnyMcA
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Laboratory
New paper indictaes that the source of the radiation is the sun
Pre-print available here
Jonny
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JonnyMcA
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Laboratory
This graph is a histogram of close distances of C/2013 A1 based upon a Monte Carlo run using the known uncertainty
The horizontal axis is the pass distance, with the width of each bar equal to the radius of Mars. the vertical axis is the number of "test particles" (out of 10,000) that passed the planet at that distance. Red marks a collision, and Orange marks distances within the
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JonnyMcA
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Laboratory
If you didnt see the BBC documanetary, or you are not in teh UK, you can view part one (and presumably other parts) here < ;
The channel 4 one is here though it seems blocked in the UK, but other countries might be able to view it.
Jonny
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JonnyMcA
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Laboratory
Just watched a documentary on channel 4 as well as teh BBC one, and thought that teh Channel 4 one was better. It was nice though to see my old Astronomy lecturer Alan Fitzsimmons get a prominent role in the BBC one.
Jonny
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JonnyMcA
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Laboratory
Another archival image of C/2013 A1 has been found, taking the observation period to 148 days. Using this and recalculating using all other observations, the nominal distance of the comet from Mars is 0.00039 AU with a calculated impact probability of 0.08% .
Jonny
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JonnyMcA
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Laboratory
Hi Rick,
I am already a member, but I tend not to worry too much about pay-walls, since I have access to quite a few journals, and those that I don't have access to I find that if you email the authors of an article they are usually more than happy to provide a copy of the article.
Jonny
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JonnyMcA
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Laboratory
I can do better than that, I can reproduce it here in its entirety, since there is not much point in publishing it elsewhere as it was just a comment for publication in their correspondence section with regards the subject of the Russian meteor in that the author of the Nature news article said that it was the largest event in a century.
QuoteThe title and contents of the News Article “Russian
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JonnyMcA
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Laboratory
Good stuff Tommi. And on the flip side, I got my first Nature rejection letter yesterday. It was only a correspondence article, and i wasnt expecting for it to get published anyway (it is nature after all), but it was worth the try
Jonny
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JonnyMcA
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Laboratory
More observations have now got a nominal pass distance of 0.000276 AU for the comet, but with still a large enough uncertainty that a collision is not yet ruled out
Jonny
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JonnyMcA
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Laboratory
Here is a Google Earth .kml file which shows the trajectory of the bolide as supplied by Alan Fitzsimmons of Queen's University Belfast . It denotes the 16 seconds of luminous flight, and ranges from an altitude of 91 km down to about 15 kilometers. Vertical lines mark disintegration points.
You can see that its angle of incidence is about 20 degrees, and has a heading of about 282 degre
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JonnyMcA
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Laboratory
But there is still the absence of the 837 apparition of Comet Halley in the Irish Annals, but was recorded in other societies. The point is that a conspicuous celestial event could miss being recorded by some societies but recorded by others. The local weather of course plays a big part in this, and Ireland can be a rather grey and soggy place at times, which could explain why Halley was not re
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JonnyMcA
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Laboratory
Indeed, in a society steeped in religion, celestial events could be used as propaganda.
I have copy of McCarthy's paper, and there is no mention of anything exciting happening around 774-776, nor as far as I am aware in the Irish Annals. Then again, there is no mention of a comet in AD 837, when Comet Halley made its closest approach to earth at 0.04 AU with a possible tail length of about
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JonnyMcA
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Laboratory
Hi Hermione,
Just to clarify something, I am not suggesting that something happened in 793 or 794 (at least not with respect a supernova or related to 775). They were merely two events I was using to show that Roger of Wendover and the Anglo-saxon chronicle could report the same events, but in different years, with Roger seemingly being a year or two later, and thus his 776 date of events cou
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JonnyMcA
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Laboratory