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Solar polar flip every solar max...
Posted: Wed Feb 02, 2011 12:52 pm
by Archie
If the sun does a polar flip every solar max, as I've recently discovered, then how do we know the upper hemisphere is 'northern'? Or is it standard astronomical notation to label the top of a spacial body as north? (Unless like Uranus spins on a horizontal axis).
Plus, ...well, that's a seriously huge event, does that mean it it would be dangerous to fly through the South Atlantic Anomaly as that is going on?
Archie
UK
Re: Solar polar flip every solar max...
Posted: Wed Feb 02, 2011 3:37 pm
by Chris Peterson
Archie wrote:If the sun does a polar flip every solar max, as I've recently discovered, then how do we know the upper hemisphere is 'northern'? Or is it standard astronomical notation to label the top of a spacial body as north? (Unless like Uranus spins on a horizontal axis).
When you view a rotating body along its rotation axis, you are on the north side of that body if you observe the apparent rotation to be counterclockwise. If you like hand rules, curl the fingers of your right hand and point your thumb up. The fingers show rotation direction, and the thumb is pointing north. This applies for Uranus as well- its axis of rotation is simply tilted significantly with respect to its orbital axis (as is the Earth's- just not quite so much).
Plus, ...well, that's a seriously huge event, does that mean it it would be dangerous to fly through the South Atlantic Anomaly as that is going on?
The reversal isn't a big event. It isn't sudden, either- the solar cycle is defined by the 22-year oscillation in strength and direction of the Sun's magnetic field.
Why would the conditions in the South Atlantic Anomaly be different during Solar Minimum? The Sun puts out particles throughout its cycle- more, in fact, when it is magnetically active. And the Sun's magnetic field doesn't significantly affect Earth's, and it is Earth's field that is responsible for the South Atlantic Anomaly.
Re: Solar polar flip every solar max...
Posted: Thu Feb 03, 2011 1:07 am
by Archie
Mmmm.... that's interesting, so we truly could land on a foreign world with the correct counter clock rotation to indicate north in the upper hemi, but magnetically flipped with compass mag north in the bottom hemi?
My thought on solar polar flip was a very wild magneticaly gravitationaly and radiationaly unpredictably stormy-out-there sort of thing, at this solar max, so don't let the kids go joy-riding out in space in THAT weather, so the thought was that flying thro the SAA could perhaps be a tad toxic, due to a truly reduced van Allen protective shield. As opposed to a solar min, with no sun spots and reduced bad stuff out there, or is the solar radiation/wind not changed radically between min and max?
So, as you say it's not a quick flip, how long would our star take to fully flip, then? And does it not do all that precessional wobble, while in flipping? Mmm...I guess it's a ball of nuclear fusion, so guess again wobble isn't significant in star terms.
Total respect Chris for your cool, I read thro a very painful thread!
Archie.
Re: Solar polar flip every solar max...
Posted: Thu Feb 03, 2011 6:19 am
by Chris Peterson
Archie wrote:Mmmm.... that's interesting, so we truly could land on a foreign world with the correct counter clock rotation to indicate north in the upper hemi, but magnetically flipped with compass mag north in the bottom hemi?
Sure... there's no real connection between a body's rotational axis and its magnetic axis. The magnetic poles of the Earth flip every few hundred thousand years, but the rotational axis is very stable. Depending on when in Earth's history you visit, your compass could point either north or south, and at times the field was so weak a compass wouldn't work at all. Or the magnetic axis could be so far from the rotational axis that a compass would be useless unless you knew where you were on the Earth.
My thought on solar polar flip was a very wild magneticaly gravitationaly and radiationaly unpredictably stormy-out-there sort of thing, at this solar max, so don't let the kids go joy-riding out in space in THAT weather, so the thought was that flying thro the SAA could perhaps be a tad toxic, due to a truly reduced van Allen protective shield. As opposed to a solar min, with no sun spots and reduced bad stuff out there, or is the solar radiation/wind not changed radically between min and max?
The magnetic field oscillation over 22 years is pretty smooth and gentle. At solar maximum, there are more flares, and those throw out lots of energetic particles. It's why there are more auroras when the Sun is active, and certainly the space environment is a little riskier. But it's nothing unmanageable. Barring the occasional massive flare, there isn't all that much difference in the solar system environment as the Sun goes through its cycle.
So, as you say it's not a quick flip, how long would our star take to fully flip, then? And does it not do all that precessional wobble, while in flipping?
The Sun doesn't wobble. It has a very stable axis of rotation. What happens over 22 years is that its magnetic field goes from strong north pointing to zero to strong south pointing to zero and back to strong north pointing.
I think you might be mixing up things you've read about the Sun's magnetic field and things you've read about Earth's.