Ancient Assyrian Auroral Record Helps To Shed Light On The Sun & Powerful Magnetic Storms

A Neo-Assyrian table from the Library of Ashurbanipal has provided space physics researchers with what may be one of the earliest descriptions of the aurora borealis.

How many hundreds or thousands of years have reliable records of the aurora been kept? It turns out a lot.   We now know, for example, of the existence of an Assyrian record dating back as far as 660 BCE, or more than 2,600 years ago.  This is a big deal. Especially in terms of the study of the aurora, as well as ancient solar behavior,  and how both relate to current solar behavior.

Documenting aurorae helps space and solar physicists better understand patterns of solar activity. Magnetic  storms on the Sun can release giant plumes and jets of materials, some of which fall back into the Sun and some of which are  ejected and spewed across the solar system, for example in the solar wind.  Particles that make it to Earth can be funneled  along magnetic field lines into Earth’s upper atmosphere (magnetosphere0, where they strike atmospheric particles, causing them to glow. Red aurorae, like the ones documented by the ancient Assyrians, are typically caused by low- energy  electrons.

Auroras can display as both diffuse and discrete. In the first case the shape is ill-defined and the aurora is believed to be formed from trapped particles originally in the magnetosphere which then propagate into the lower ionosphere via wave-particle interactions.  Thus, multiple- colored auroras can be explained by emissions from different atoms in the upper atmosphere, mainly in the region of the magnetic poles. This is also why, of course, they are more often seen in the vicinity of the N, S magnetic poles.

A great analogy has been given by Prof. Syun Akasofu-  former Director of the Geophysical Institute in Fairbanks, AK - who compared the generic aurora to an image on a TV screen. In this case the (polar) upper atmosphere corresponds to the screen and the aurora to the image that would be projected on it, say for a cathode ray TV. The electron beam in the TV  corresponds the electron beam in the magnetosphere. In the conventional TV motions of the image are generated by the changing impact points of the electron beam on the screen. Similarly, with the aurora, its motions – such as moving sheets or curtains- are produced by moving impact points of the magnetospheric electron beams.

As far as the recovered ancient auroral record, we have to thank Hisashi  Hayakawa, lead author of a new study examining the red aurorae. Hayakawa is an astronomer at Osaka University in Japan and the Rutherford Appleton Laboratory in the
United Kingdom. Hayakawa and his colleagues identified the records by examining ancient cuneiform tablets held in the British Museum. These tablets were carved by Assyrian court scribes, whose job was to document important happenings
in the empire. They often included accounts of celestial events, like comets (ṣallummû), meteors (kakkabu rabû), and lunar and solar halos (tarbāṣu), which were thought to be omens of the future.

In the tablets studied, the Hayakawa team found two references from Nineveh (a city near current- day Mosul, Iraq) and one from Babylon  (built along Iraq’s Euphrates River) that describe red aurorae, using terms like akukūtu,  meaning red glow, or stating, “red covers the sky.” Using the authorship of the tablets,
researchers think the events happened sometime between 680 BCE and 650 BCE, a century earlier than previous records of aurorae.

Because they follow Earth's magnetic field lines, aurorae are most commonly seen near the  poles.   For example, this image of a green aurora display I took near Chena Hot Springs, AK, in March 2005:


However, it's important to note strong solar events  like x-ray flares can make aurorae visible at lower latitudes. Although today it is rare to see an aurora in the Middle East, 2,000 years ago   (owing to precession) the magnetic North Pole was
much closer to Mesopotamia, hovering over  the Norwegian archipelago of Svalbard
instead of at its current location just 4° south of the geographic North Pole.

An intriguing aspect uncovered is that the newly identified records also match
indirect evidence of solar activity. Since 2012, several studies have found isotope data of carbon- 14 levels recorded in tree rings that indicate a strong burst of solar activity during the same time period. By adding Assyrian observational evidence to these natural archival data, scientists are better able to confirm that the event was truly a space weather event caused by an extreme solar storm.

According to Ilya Usoskin, a space physicist at the University of Oulu in Finland (not involved with the new research:

"Comparing these data from natural archives to real historical records made by contemporary astrologers at the time is very  important. From it, we know that we are on the right track, because the two records match each  other.”

Let us take a brief  digression to note here that astrology and astronomy were inextricably bound in ancient times.  Indeed, the technical and detailed observations of the ancient Sumerians could rightly be said to be the birth of astronomy.  Only much later did astrology become radically divergent when it tilted into "horoscopes" or personalizing the stars for the benefit of deciphering out-sized egos.

Back to the Hayakawa research, it was found that ancient magnetic substorms occurring at the time had an intensity rivaling that from the great Quebec events in 1989.*   On March 13, a monster CME - accompanied by intense aurorae- triggered  induced dynamo currents powerful enough to knock out Quebec's power for nearly 9 hours, as well as fuse thick cables.   According to Hayakawa:

“It is likely that the [ancient] storms were considerably large. Storms with similar intensity [today] would be harmful to modern technological infrastructures.”

As I pointed out in earlier, related blog posts e.g.

• The CME That You DON'T Want to See!

An understanding of the historical frequency of solar storms (e.g. the Carrington event of 1859)  and learning how to predict such events are important for mitigating their effects on our tech-oriented society. The historical data can also help solar and space physicists model how often such extreme events occur and better assess the probability of similar extreme events.  In the words of space physicist lya Usoskin:

“Direct observations from the last decades are not very useful here because they just cover too short a period of time, Such historical records are very helpful because now we know that during the last, say, 3,000 years, there were three events of  that magnitude (equal to the Quebec storm), which means that on average, we may expect such disasters to occur a few times per millennia.”

Hayakawa et al's paper can be found in: Astrophysical Journal Letters  and also below:

https://earth-planets-space.springeropen.com/articles/10.1186/s40623-016-0571-5


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*  Given the aurora is basically regarded as a magnetic substorm we use what are known as "substorm models".  In most current ones some dynamo action is required which sends currents to specific regions to provide a Lorentz force: (J ⊥ X B) where J ⊥   is the vertical current density and  B  the magnetic induction associated with the system.. At a particular altitude then, these J ⊥ currents can trigger a substorm.)

It's Not The Reversal Of The Earth's Magnetic Poles That Ought To Excite Apocalyptic Alarms

Thee seems to be a lot of arrant babble circulating about a reversal of Earth's magnetic field and the cataclysm that it may portend.  In particular,  that we are headed for some kind of major catastrophe,  taking out billions.  Let me assure one and all it won't happen.

First,  some basics on terrestrial physics.  The Earth has a magnetic field as a result of the molten iron core within it and the free electrons in that molten matter being spun around by Earth's rotation.  The effect is basically a reverse dynamo action, e.g.

 Here the rotary motion of the molten iron core creates  strong electric currents that in turn generate the planetary magnetic field with north and south magnetic poles.   We call this a dipole field because two poles are generated by the action.

The planet's dipole field is extremely critical in terms of maintaining its residual magnetic field of roughly 3.1 G (gauss) which in turn implies the capacity to provide a magnetosphere (see top graphic) that's capable of intercepting the high energy particles of the solar wind as well as other solar-flare- triggered particles. e.g. high energy protons. The key point to grasp is that the Earth's spinning iron core generates the Earth's magnetic field (N and S poles)  which in turn gives rise to its protective magnetosphere.  Its basic components are the: magnetopause, magnetosheath and magnetotail.

Now, while the news of a "reversal" of the Earth's magnetic field may sound alarming to many, e.g.  an article in Undark Magazine declared, “It’s time to wake up to the dangers and start preparing,” this is mainly the stuff or pseudo-science and hysteria. The latter is based on hyping the peril of  devastating streams of  "malevolent" cosmic radiation that would wreak havoc on lives and power grids.  In fact, there is a real risk, but it is from enormously violent proton flares or associated CMEs,  originating at the solar central meridian,  and only if there is also no field at all.  But  even that probability is very much less than touted by the scare mongers.

My point is that when one dives into the stories under the headlines  things become much less alarming.   Let's clear the air on the meme that scientists were caught "off guard".   Nope. All scientific "eyes" have been where they needed to be in terms of monitoring the planet's magnetic poles. They weren't tweeting all day or watching FOX News like our so-called President.

All of the  responsible institutions and monitors have remained active and even during the recent federal shutdown those facilities  were not shut down.  They were doing their due diligence and monitoring magnetic pole phenomena, as well as magnetospheric events including any substorms.

Further, both  the United States and Britain have collaborated on issuing an updated World Magnetic Model every five years to make sure everyone’s on the same map.  Can't have any Arctic explorers getting lost because their compasses aren't tracking the real N. magnetic pole after all.   And by way of clarification -  and so no one gets needlessly hyper  -   the Earth’s magnetic poles have always been on the move, and have even swapped places several times over the eons.  As noted earlier the reason is that the molten iron deep inside the Earth "sloshes"  around, shifting the magnetic field with it.  (See the diagrams again).   For now, it is situated four degrees south of the geographic North Pole.

Now, how did the current scare-a-thon get started?  The next update for magnetic pole locations had been due in 2020. But early last year geo-scientists found that the north magnetic pole was heading eastward at an unusually rapid rate, about 35 miles a year. They then decided to adopt a new model, which became available soon after Trump's  shutdown ended.

The model’s out now, which is good news for planes flying over the North Pole, and for airports that name runways in relation to the magnetic north. Also for GPS providers and for anyone else in need of precise directions. For most other places there's minimal  need for corrections. South of the northern tip of Scotland, for example,  the correction amounts to only a small fraction of a degree.  Will you notice that on your compass? Not likely!

Never mind, as in the case of the HAARP (High Frequency Active Auroral Research Program) the conspiracy whackos have worked overtime to get their minions into a lather. Thus, the news of the rational updating of the magnetic pole model has not prevented online tabloids  and assorted crazies (likely from the FOX realm) having an apocalyptic field day.

 Recall in the case of HAARP,  the purveyors  of conspiracy ideations (I hate conferring gravitas using the term "theorists")   claimed that it was capable of "modifying weather, disabling satellites and exerting mind control over people.  Some  crackpots even blamed the program for causing earthquakes, droughts, storms and floods, diseases such as Gulf War syndrome and chronic fatigue syndrome

In the case of the unexpectedly faster moving north magnetic pole, the part that feeds the nutjobs' doomsday scenarios is the possibility that the poles are preparing for another polarity reversal, which would cause a compass to point south instead of north. "Omigod! Compasses pointing north! It's the sign of the Antichrist! Aieeeee!" 

But hold strain! The quirk is normal and over the past 20 million years has occurred, on average, every 200,000 to 300,000 years. The last one was about 780,000 years ago, so another may be overdue.  

That could lead to a temporary weakening of the magnetic field that protects Earth from cosmic radiation. And that’s where the doomsday scenarios pile in. a world in which the inhabitants get bombarded mercilessly by intense solar and other cosmic radiation - literally baking us to cinders. But it's basically BS.  A form of mutated garbage roughly along the lines of the HAARP conspiracy bollocks and "The Great Awakening"  insanity - on which I will have more to write in the near future.

The specter of an Earth left without a magnetic shield has come up before, notably during the Mayan "apocalypse"  that predicted the world would end in 2012.   But which turned out to be a big boring dud  that I'd even predicted beforehand, e.g.

.http://brane-space.blogspot.com/2012/12/no-therell-be-no-mayan-apocalypse.html

Back then, NASA posted a response that explained the science of pole reversals and concluded that “there is nothing in the millions of years of geologic record to suggest that any of the 2012 doomsday scenarios connected to a pole reversal .   Never mind. All the catastrophe obsessives  -  including a number who showed up on the All Experts Astronomy forum, wasting my time  -  wouldn't let it rest. Or accept NASA's rational explanation. Why would they when we know the untutored brain doesn't operate that way.   

In previous posts I have tried to explain the basis for this. For example,  noting that the brain activity of ancient people lacked the sense of metaphor, irony and individual identity that characterizes a more advanced mind. Such mentalities  also lack self-reference and introspection, a facility which enables modern man to not only think but think about his thinking. 

All of this was pointed out in Julian Jaynes masterpiece:  The Origin of Consciousness in the Breakdown of the Bicameral Mind', 1976 )  But in the modern context, it means that too many brains are still operating at an ancient or primitive level. I mean look at Donald Trump for instance. No self-awareness, no introspection and absolutely no sense of irony or metaphor.  (Aspects of his troglodyte nature any Dem presidential candidate will need to exploit)

Now, let's leave the realm of fantasy horrors and get to the real and imminent threat:  In a manner of technical speaking, we  humans are causing the Earth to "wobble."   But not from anything to do with magnetic poles drifting.  Rather, the geographic North Pole, the focus of the planet’s spin axis, is also shifting east.  This is not as striking as its magnetic counterpart, but for the wrong reasons: rapid global warming in the Arctic.  The North and South Poles always wander a bit  (geodesy deals with this and  computes yearly corrections), but the movements have increased, and  climate scientists theorize that the redistribution of mass on Earth, i.e.  as glaciers and ice sheets melt,  is one of the major reasons.

 Several recently published studies warn that ice at both ends of the Earth is melting far faster, and oceans are warming more rapidly than previously thought.  This suggests that scientific estimates of a warming planet have been too conservative. Those are the headlines that should be causing real concern.  This is what global citizens and especially apocalypse-prone Americans - ought to be worried about.  Just like I used to tell questioners on All Experts, i.e.  to worry more about climate change than an exploding star in another galaxy.  So also I keep pressing current readers of my blog to reckon planetary threats rationally,  and not waste time obsessing over remote or improbable ones.

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Addendum- Technical Details on Magnetic Poles:

The magnetic flux density defined for the Earth is given as (Hargreaves, The Solar-Terrestrial Environment, Cambridge University Press, p. 150):

B(r,L) = M/r    [ 1 + 3 sin 2 L]  1/2

where M is the dipole moment (M ~  10  25.9 G cm 3, with G in gauss), r the geocentric radial distance and L the magnetic latitude (e.g. 70 deg).

Generically, the vector magnetic field at vector position x due to a magnetic dipole of vector dipole moment m at the origin, is given by:

B = {3(m*x)x - x 2} / ‖ x‖ 3

Meanwhile, the field components in the r and L directions are respectively (Hargreaves, ibid.)

B(r) = - 2M sin(L) / r 3

B(L) = M cos (L) / r 3

The characteristic time for variation of the Earth's magnetic field is given by the differential equation:

dB/dt = B(r, L) /t

Which can be solved using Fourier transforms, at least approximately.

Solutions To Space Plasma Physics (3) Problems

1) The plasma parameter is defined:

L  =  n _o  l³ _D

From the values given (T =10 ⁶ K, and n = 10 ¹⁰ /m³)

L  =  n _o   l³_D    =   ( 10 ¹⁰ /m³) (0.30  m ) ³

L  =   2.9 x 10 ⁸   

The number of particles is defined:

N  =   4p n _o  l³ _D  / 3 

N =  (4p)(9.2 x 10 ⁶ ) / 3  =  1.2 x 10 ⁹  

2)For the solar atmosphere, first find the Debye length:

l _D,s =[kT _s / 4p  Z _s² n _s  e² ] ^1/2

For which Z= 1 (hydrogen bulk plasma)   Then:

l _D,s =[kT _s / 4p n _s  e² ] ^1/2

l _D,s   =

[(1.38 x 10^-23  (10 ⁴ K) (8.85 x 10 ^-12 F/m)   / (4p)  (10 ²⁰/m³)  e² ] ^½

l _D,s   =  1.9 x 10 ^{- 7}   m

Then the plasma parameter is:

L  =  n _o  l³ _D    =   ( 10 ²⁰ /m³) (1.9 x 10 ^{- 7}   m) ³

L  =  0.74   

The number of particles is:

N  =   4p n _o  l³ _D  / 3  

N =  (4p)(0.74) / 3 = 3.1   »   3.0

Note that L, N are drastically less than for the helium plasma.

 3)  For the laser fusion plasma we have for the Debye length:

l_D ,  =

[(1.38 x 10^-23  )(10 ⁷ K) (8.85 x 10 ^-12 F/m)   / (4p)  (10 ²⁹/m³)  e² ] ^½

l _D,s   =  1.9 x 10 ^{- 10}   m

For the tail of Earth’s magnetosphere we have for the Debye length:

l _D,s  =

[(1.38 x 10^-23  (10 ⁷ K) (8.85 x 10 ^-12 F/m)   / (4p)  (10 ⁶/m³)  e² ] ^½

l _D,s   =  61.6  m

For the laser fusion plasma we have for the plasma parameter:

L  =  n _o  l³ _D   =  

( 10 ²⁹ /m³) (1.9 x 10 ^{- 10}   m) ³

L  =  0.74   

N = 4p n _o  l³ _D  / 3  =  3  

For the tail of Earth’s magnetosphere we have for the plasma parameter:

L  =   ( 10 ⁶ /m³) (61.6  m) ³

L  =  2.3 x 10 ¹¹   

The number of particles in the Debye sphere:

N = 4p n _o  l³ _D  / 3  =  9.7 x 10 ¹¹   

The values L, N are vastly larger for the tail of Earth’s magnetosphere

4)Can a plasma with n _o = 10 ⁶ /m³    be maintained at an electron temperature of 100K?  (Hint: Calculate the density limit using the plasma parameter).

For these numbers the plasma parameter is:

L  =  n _o  l³ _D  

And the Debye length is:

l _D =10 ^0.84   (ÖT/ Ön)  =  

 10 ^0.84   (Ö100K / Ö(10 ⁶ /m³)  =     0.069 m

So that:  L  =  n _o  l³ _D  =     ( 10 ⁶  /m³) (0.069 m) ³  

  =  3.0 x 10 ⁹   

The number of particles is:

 N  =   4p (3.0 x 10 ⁹ )   / 3  = 1.2  x 10 ¹⁰   

The value N is much larger than unity and hence  is consistent with the principle of shielding so the plasma can be maintained at the given electron temperature.

5) In the limit 1/N << 1 and 1/N ® 0  we say a plasma is “collisionless”. Do any of the plasmas cited in the previous problems qualify as collisionless?

The values 1/N for the given plasmas are as follows:

helium plasma: 1/N = 1/ 3.8 x 10 ⁷   =   2.6  x 10 ^{- 8}   

solar atmosphere: 1/N = 1/3.1 = 0.32

laser fusion plasma:  1/N = 1/3.1 = 0.32

tail of Earth’s magnetosphere: 1/N = 10 ^{– 12}

The values 1/N show  that only the helium and magnetospheric plasmas can be considered as collisionless.

Selected Questions-Answers From All Experts Astronomy Forum (The Nature of the Aurora)

Question: I am interested in learning more about the aurora, what causes it and also what gives rise to the red and green displays.  Any insights here would be much appreciated! - Sally, Toronto

Answer:

To understand the aurora, one can visualize the Earth as a giant spherical magnet, with magnetic  field lines extending from the north to south (magnetic) pole.


 These  magnetic field lines have the property that any charged particles (+ protons, - electron or ions), say that are expelled from the Sun,  that approach, will spiral along them.  The Earth itself is "bathed" in the solar wind, a stream of high speed charged particles that flows into space, originating from the Sun's corona. (A hot, gaseous envelope that spews these particles out continuously – more so when there is a violent explosion known as a Solar Flare)  Around the Earth the speed of these particles can reach 400- 500 km/second.  The dumbbell -shaped region,  in which the incoming particles become trapped and ultimately - via acceleration -  generate the aurora, is known as the magnetosphere.

During high solar activity (e.g. near sunspot maximums) a higher flux of these charged particles inundates the solar wind, and the region around the Earth. The Earth's magnetic field traps these charged particles, and the highest density is around the polar regions - which we refer to as the "auroral ovals".  The Aurora Borealis, for example, which I observed and photographed north of Fairbanks, Alaska in 2005, e.g.

manifested as part of the huge ring known as the auroral oval, located above the Earth's Geomagnetic North pole (which is not the same as the geographical north pole).   In this region, very large electric currents are set up, as the charged particles start moving in unison about the magnetic field lines. These currents can easily reach a few million  amperes.As this discharge occurs, one or more outer electrons is stripped from the atoms, for example from oxygen in the atmosphere - then recombines again - to form new (e.g. oxygen) atoms.

With this recombination - there is accompanying emission of light, for a certain part of the visible spectrum   For example, in the case of recombination of oxygen atoms - their emitted light is in the green region of the spectrum, such as seen in my photograph above. Hence, we get the green aurora. The remarkable red aurora is produced by emission at the 630 nm (nanometer) line of oxygen and at relatively high altitudes (e.g. 200-600 km) compared to green - which tends to form below 100 km and the oxygen line at 557 nm is excited.

Auroras can also display as both diffuse and discrete. In the first case the shape is ill-defined and the aurora is believed to be formed from trapped particles originally in the magnetosphere which then propagate into the lower ionosphere via wave-particle interactions.   Thus, multiple- colored auroras can be explained by emissions from different atoms in the upper atmosphere, mainly in the region of the two magnetic poles. This is also why, of course, they are more often seen in the vicinity of the N, S magnetic poles.

A great analogy has been given by Prof. Syun Akasofu-  former Director of the Geophysical Institute in Fairbanks, AK - who compared the generic aurora to an image on a TV screen. In this case the (polar) upper atmosphere corresponds to the screen and the aurora to the image that would be projected on it, say for a cathode ray TV. The electron beam in the TV  corresponds the electron beam in the magnetosphere. In the conventional TV motions of the image are generated by the changing impact points of the electron beam on the screen. Similarly, with the aurora, its motions – such as moving sheets or curtains- are produced by moving impact points of the magnetospheric electron beams.

In gauging the power and intensity of auroras at different times, it is useful to remember that ultimately the aurora derives its power and potential from the Sun and specifically the charged particles of the solar wind. This is why the most spectacular displays are usually near sunspot maximum. Around those times the currents can attain magnitudes of  10⁶  A  (amperes)or more. To give an example, during a quiet Sun interval  the residual power for the magnetospheric generator is on the order of maybe a tenth of a megawatt. If we see a new cycle coming on and solar wind activated – we may get that power up to a million megawatts for a few hours.

Two excellent books to get, to learn much more about the physical nature and dynamics of the aurora,  are:

'Exploring the Secrets of the Aurora' - by Syun Akasofu

https://www.amazon.com/Exploring-Secrets-Astrophysics-Science-Library/dp/0387450947

And: 

'Storms in Space' - By John W. Freeman

Prof. Akasofu's text is more comprehensive  and written at an academic level, but well worth the effort if you can manage it. Freeman's book is at a more popular level, but I'd recommend it before going to Akasofu's.