Part of me kind of wishes that this had some trivial, totally safe and innocuous consequence that you could still appreciate somehow with a Mr. Wizard type experiment.
No, it's a chaotic system that is quasistable for an average of 11 years at a time before it flips to the opposite orientation with respect to the spin axis. The Earth's magnetic field, generated by currents in the liquid outer core, is a similar magnetohydrodynamic system that has no apparent periodicity.
Disclaimer: I worked on the solar magnetic field for two summers.
Whether the sun is chaotic in the technical sense (i.e. the butterfly effect) is still open to question [1]. The solar magnetic field is poorly understood. In the 1980s, everybody thought that a particular model (mean-field dynamos IIRC) had it all figured out, but new observations from helioseismology showed them wrong. Wikipedia has a good article on the solar cycle: https://en.wikipedia.org/wiki/Solar_cycle My advisor wrote a more technical overview: http://solarphysics.livingreviews.org/Articles/lrsp-2010-3/a...
The last time a geomagnetic reversal occurred on Earth was 780,000 years ago (with a possibility of a brief one occurring 41,000 years ago) [1]. I wonder what it will feel like when it happens again...
Of course it's not a monopole, but the dipole idea is also too simplistic, as is the idea of "poles". Presumably, the dipole moment of the Sun has become very small but there are still higher orders at work. Thus, the field of the Sun will look very much more complex than the simple dipole field [0].
A possible configuration would be that both geographicals poles of the same sign, but the field around the equator is of a different sign, like a quadrupole perhaps.
Disclaimer: I'm a physicist but not an astrophysicist.
Correct. I'll do some digging around to find the polarity maps we have around the lab here and post them if I find them. At times, there really isn't a clear 'pole' of the sun, and octopoles can sometimes be found.
E: Here's a link to one of those maps. I'll see if I can find any better.
The light spectrum emitted by the Sun has "spectral lines", or emission features (deep dips or strong peaks) that are determined by light-absorption or light-emission from specific elements (e.g., Nickel, Iron, and of course Hydrogen) in the Sun's atmosphere.
If the little packet of stuff that was absorbing light is moving toward or away from you, the characteristic frequencies of all its spectral lines will be Doppler shifted. So, you can measure the velocity of that packet of stuff by seeing how much the line is shifted. Since you have a lot of photons, you can do this independently across the Sun's surface and get a spatially-resolved map of velocity ("Dopplergram", http://solar-center.stanford.edu/dopplergram.html).
If the little packet of stuff was in a magnetic field, its spectral lines will be split into sub-lines due to the Zeeman effect. So, you can also measure the spatially-resolved magnetic field of the Sun, and this is called a "magnetogram".
It is kind of surprising that this measurement can be made at all.
Doppler shift. One of the simplest and most deeply useful physics principles. Things you learned in high school that are actually useful way down the road. Basic trigonometry (Sohcahtoa) falls in the same category for me.
So true. I have been watching an excellent lecture series by Prof. Charles Bailyn (Yale U.) where he goes into some current work in astrophysics (2007) using calculus-free physics. (It's at http://oyc.yale.edu/astronomy/astr-160, and other places like iTunes U.)
It's amazing how deeply useful Doppler shift is; he returns to it thematically at least twice, talking about exoplanets as well as black holes. "We can't see them directly, but we can see them through the way they interact with other things."
Observing the behavior of plasma around the Sun is probably one of the indicators. Also, the Zeeman effect in the Sun's spectrum measures the absolute intensity quite directly; I'd assume that the zero transition could be observable this way.
Once they observe the photospheric magnetic field, they use it as a boundary condition for models that project upward into the corona. They can't observe the field directly in the corona (this might be an experimental capability somewhere, but it is not done observationally anywhere).
They do observe the movement of plasma in the corona, to check the field lines predicted by the models.
This statement "This change will have ripple effects throughout the solar system" will sound like an doomsday event to an average reader, in reality there nothing that would affect you.
At least they almost immediately mention that it is a common event.
Personally I prefer a humorless HN. A culture of humur on the internet devolves fairly quickly into 4chan themed cat pictures and nothing but funny pics.
A common trick to insert a EU-style plug into a UK-style socket is to temporarily insert something in the ground pin socket. An ordinary house key works well, and has the added bonus of shocking bystanders.
Granted, UK-style plugs really are excellent pieces of engineering, best appreciated when upturned and trod upon in the dark.
That actually only happens on reasonable quality ones. Old and cheap shitty ones usually get stuck open or break off very rapidly. The BS spec is only good until 1 insertion after the point of sale.
If you're still using magnetic platters, it would be a good idea to take them apart and flip the disks to reduce data corruption. There are also tools that will do this for you in software by flipping every bit on the disk and using 1 for 0 and vice versa. You can also do this with dd in Linux, just make sure you flip the binary description bit in the Disk Parameter Table.
That's pretty easy, imagine the fun the NMR/MRI people are about to have. Those suckers are heavy.
Also my wife is a member of the "interior decoration means covering your fridge with magnets" tribe, so now I have to flip all of them over. Someone, please create a startup for online classes for interior decorating.
For ham radio HF propagation above 20 meters? Well, not really. Enjoy 10M while you can... I hope the next cycle in about a decade has better flux numbers. Es on 6M is fun, but I want some months long round-the-world F2 propagation modes.
(Seriously its interesting the article didn't mention how unusually weak the latest cycle has been. Usually the peak is much higher leading to happier ham radio operators. So the "news" or "journalism" is the unusual weakness of this cycle, but instead we get human interest story...)
Aside from the stereotypical "this individual cycle is weak" most recent solar coverage has contemplated Maunder Minimum effect and stuff like that. The wiki article is pretty good, summary is every time a cycle is wimpy everyone temporarily jumps on the bandwagon that its a semi-permanent long term decline etc etc.
Amateur radio can be rewarding. You can build radios/antennas, explore physics, yak with folks around the world without internet/telecom companies or do public service. Current nifty ham technology is SDR, (Software Defined Radio).
Just because you mentioned the internet and "everything must be connected with Snowden," I wonder if the NSA is tapping all short-wave comms? You'd think yes, because that is what spooks on all sides used for encoded messages. But then again, with the focus on internet, maybe the SW-recorder got neglected in a back-room (unlikely, probably just another pipe into that Utah data center).
Tapping a thing and understanding what you are listening to are two totally different things. Theoretically broadcasting an encrypted message in which third parties cannot possibly have access to the endpoints is still the safest way to handle sensitive data. This is part of the reason why 'Numbers Stations' are so popular with us geeks.
It's easier than you think to "capture" selected chunks of the RF spectrum. DOD, etc, have had this capability for decades, civilians have had scanners and broadband radios for decades. Amateurs can record entire HF bands and decode multiple CW and other signals in real time with modern receivers and computing power.
Actually, this looks more interesting than at first look. The previous flip was around '89, which saw the Eastern Europe wave of 'change'. Then 9/11. Now we have the 'Arab Spring'.
But, correlation is not causation so all remains just pure coincidences.
Not that I think that geopolitical happenstance is affected by solar magnetism, but I'm getting a bit fed up with the 'correlation is not causation' police.
No it's not, but nor is it a blanket reason not to investigate apparent parallels.
Just because the 'correlation = causation' is used to dis-infrom through findings that are bolstered by correlations, doesn't mean there's no reason to try and explore a reasonable case as to why the correlation reflects actual causation.
Correlation can infer causation in many instances.
But the GP's mention of the 'correlation is not causation' is completely warranted in this case. He doesn't think 'geopolitical happenstance is affected by solar magnetism' either. And that's exactly what is said. Though there seems to be a correlation, politics is not actually affected by the phenomenon.
> politics is not actually affected by the phenomenon.
What makes you think it does not?
It has been now shown that weather patterns in Europe during the middle ages are correlated with both warfare[1] and witch hunts [2]. Theories that explain these phenomena have been proposed.
The thing is, any astrologer during that period would get the correlation part right but the causal mechanism completely wrong. Move forward 500 years and believers in Scientism (not Science) will take the mistaken causal mechanism, confirm that it does not match with their a priori belief system, and wave off the real correlation as "fudge" or "coincidence".
Sometimes the lack of an explanation lies in the observer, for all/most of the obvious stuff has already been discovered. Lazy evaluation will take you a long way in terms of keeping an open mind.
Its mostly my own ignorance I am admitting. :) I believe the true spirit of the 'Causation is not correlation' phrase is that if the mechanism isn't obvious, don't jump to the conclusion. As your link points out, correlation is a good reason to carry further investigation.
I thought it was just a warning, like we should remember to also make hypotheses about phenomenon X that causes both the Sun's magnetic field to flip and Arab Spring events.
Also, it's worth noting that the US has a quasi-stable cycle of invading other countries for about a decade, then a roughly decade long policy of non-interventionism while they try to forget what a horrible quagmire they got themselves into the last decade.
It's caused by the sun's rotation, mostly. There are some complex magnetics that go on inside the sun, but the gist of it is that there is a differential in rotation rates between the poles and the equator of the sun. This causes field lines to be dragged along the equator, which then get knotted up and form coronal holes and other phenomena. Eventually, along an 11-year cycle, the field flips orientation.
Source: I work in a solar research lab at the University of New Hampshire
