
The Sun's Magnetic Field is about to Flip - rms
http://science.nasa.gov/science-news/science-at-nasa/2013/05aug_fieldflip/
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sidcool
Apparently this happens every 11 years. Nothing to panic, but an interesting
astronomical phenomena nevertheless.

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stephengillie
So this is an alternating current, but with a cycle time of 22 years instead
of a fraction of a second?

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Thrymr
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.

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contingencies
So astronomical objects are classifiable under a magnetic AC/DC onotology?
Wow. Seems like dualism dies hard.

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OGC
How can you get that from that reply? He specifically said they are not.

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contingencies
Err, I'm not sure how your brain works but it's obviously different to mine.
Fear not, in heterogeneity lies strength!

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return0
Great, now we can market our app as "solar magnetic field reversal-proof".

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draven
... and you have a BOFH-style excuse in case something goes wrong!

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jamesk_au
The article includes the following quotation:

"The sun's north pole has already changed sign, while the south pole is racing
to catch up," says Scherrer.

Does that not suggest that the sun is currently a magnetic monopole? Or is
that too simplistic?

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kmm
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.

0:
[http://upload.wikimedia.org/wikipedia/commons/1/17/Earths_Ma...](http://upload.wikimedia.org/wikipedia/commons/1/17/Earths_Magnetic_Field_Confusion.svg)

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el_zorro
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.

[http://www.bibliotecapleyades.net/imagenes_ciencia/ciencia_s...](http://www.bibliotecapleyades.net/imagenes_ciencia/ciencia_sol08_03.gif)

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easytiger
How do they measure it? There was nothing in the article about how this is
observed?

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mturmon
Good question.

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](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.

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brittohalloran
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.

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mturmon
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](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."

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dm2
Do I need to change any settings on my computer?

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i_cannot_hack

        > Wow, our sun is BIG...
    

Even bigger. The solar system you linked to is not even near to having the
correct proportions.

[http://upload.wikimedia.org/wikipedia/commons/8/82/Solar-
sys...](http://upload.wikimedia.org/wikipedia/commons/8/82/Solar-system.png)

~~~
acchow
This is pretty misleading. The sun's diameter is much less than 1 AU.

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taproot
Im pretty sure the sun is bigger than 1 Australia.

Sorry had to, for the confused:
[http://en.m.wikipedia.org/wiki/Astronomical_unit](http://en.m.wikipedia.org/wiki/Astronomical_unit)

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Yuioup
Will this undo the horrible decade we've had since 9/11 ?

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VLM
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.

[http://en.wikipedia.org/wiki/Maunder_Minimum](http://en.wikipedia.org/wiki/Maunder_Minimum)

In these ways, its a somewhat atypical solar news story. Which is cool.

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Yuioup
What an awesome answer to my facetious question :-) I know nothing about ham
radios or frequencies but it sounds interesting nonetheless.

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xradionut
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).

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205guy
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).

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ChikkaChiChi
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.

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arc_of_descent
Is this due to our Sun's rotation or because it revolves around the center of
the Galaxy?

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el_zorro
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

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codereflection
(╯°□°)╯︵ pʃǝıɟ ɔıʇǝuƃɐɯ

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elorant
Some comments in this thread are completely surreal.

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daigoba66
Just wait until it happens again here on Earth.

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dm2
Birds and people who haven't adopted GPS will be screwed...
[http://en.wikipedia.org/wiki/File:NASA_54559main_comparison1...](http://en.wikipedia.org/wiki/File:NASA_54559main_comparison1_strip.gif)

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biot
This entire thread has turned into 2005 Slashdot.

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SmokyBorbon
Nothing to do with global warming people. That's still cow farts. Move along.
Nothing to see here.

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boothead
So the Myans were right all along!

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rabino
Nope.

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boothead
What about homoeopathy - will that still work?

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raverbashing
Yes, but you'll have to shake it upside down

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muloka
I know I'm stating the obvious though these comments are hilarious. Keep'em
coming.

