It's because the Earth's magnetic field is not a perfect dipole so the Northern and Southern "dip poles" where your compass would point directly to the ground or the sky don't have to be exactly opposite each other, indeed they are not even approximately opposite each other right now.
The South dip pole lies at a lattitude of 64.28 degrees South, outside Antarctica, in the open ocean, also outside the Antarctic circle.
While the North magnetic pole is far closer to the pole, almost directly at it right now:
As you see the N. magnetic pole is continuing to move closer to the geometric N. pole and the S. magnetic pole is continuing to move away from the geometric S. pole. So this disparity is growing.
Back in 1900 the disparity was only 1.26 degrees of lattitude - S. pole at -71.72 and N. dip pole at 70.46.
They crossed over in between, in 1915 the difference was only 0.23 degrees, and some time between 1910 and 1915 they must have been both at the same lattitude (with opposite signs). But not directly opposite each other even then, because in 1915 the longtitudes differed by 114.43 degrees instead of 180 degrees, a disparity of 65.57 degrees.
And now the S. dip pole is at -64.11 and the N. dip pole at 86.29, a disparity of 22.18 degrees!
That's the actual dip pole - the point where your compass would point directly towards the ground, or the sky.
But you also have the idealized "geomagnetic poles" which come from best approximations of the complex Earth magnetic field as an idealized dipole.
That's inclined at 10 degrees.
But the Aurora occur around the dip pole rather than the geomagnetic pole, following the field lines of the Earth's magnetic field, so that's why the Southern aurora are offset.
I think it would be more obvious in this photo if the aurora was closer to the dip pole:
Here is a stunning video of the Aurora Borealis from the ISS in 2012. Sadly doesn't give you a good idea of where it is relative to the geographical S. Pole, just a cool video of it.
And a compilation of various videos of it here
But they are a little too close to the Earth and too much cloud to get a good idea of it's geographical position.
Here though is a video of the Aurora Australis taken from further away by the Aurora Polar Explorer
And real time map of it just now (as of writing):
Aurora Australis Forecast. How to see the Southern Lights.
I don't think it is quite centered on the Southern dip pole, perhaps somewhere between the geomagnetic and the dip pole?
Compare
(dip pole in red, geomagnetic in blue)
Perhaps because the aurora is strongest a bit of a way away from the dip pole.
The maps and figures are from British Geological Survey - Magnetic Poles
The South dip pole lies at a lattitude of 64.28 degrees South, outside Antarctica, in the open ocean, also outside the Antarctic circle.
While the North magnetic pole is far closer to the pole, almost directly at it right now:
As you see the N. magnetic pole is continuing to move closer to the geometric N. pole and the S. magnetic pole is continuing to move away from the geometric S. pole. So this disparity is growing.
Back in 1900 the disparity was only 1.26 degrees of lattitude - S. pole at -71.72 and N. dip pole at 70.46.
They crossed over in between, in 1915 the difference was only 0.23 degrees, and some time between 1910 and 1915 they must have been both at the same lattitude (with opposite signs). But not directly opposite each other even then, because in 1915 the longtitudes differed by 114.43 degrees instead of 180 degrees, a disparity of 65.57 degrees.
And now the S. dip pole is at -64.11 and the N. dip pole at 86.29, a disparity of 22.18 degrees!
That's the actual dip pole - the point where your compass would point directly towards the ground, or the sky.
But you also have the idealized "geomagnetic poles" which come from best approximations of the complex Earth magnetic field as an idealized dipole.
That's inclined at 10 degrees.
But the Aurora occur around the dip pole rather than the geomagnetic pole, following the field lines of the Earth's magnetic field, so that's why the Southern aurora are offset.
I think it would be more obvious in this photo if the aurora was closer to the dip pole:
Here is a stunning video of the Aurora Borealis from the ISS in 2012. Sadly doesn't give you a good idea of where it is relative to the geographical S. Pole, just a cool video of it.
And a compilation of various videos of it here
But they are a little too close to the Earth and too much cloud to get a good idea of it's geographical position.
Here though is a video of the Aurora Australis taken from further away by the Aurora Polar Explorer
And real time map of it just now (as of writing):
I don't think it is quite centered on the Southern dip pole, perhaps somewhere between the geomagnetic and the dip pole?
Compare
(dip pole in red, geomagnetic in blue)
Perhaps because the aurora is strongest a bit of a way away from the dip pole.
The maps and figures are from British Geological Survey - Magnetic Poles
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
4.8m answer views110.4k this month
Top Writer2017, 2016, and 2015
Published WriterHuffPost, Slate, and 4 moreHuffPost, Slate, Forbes, Newsweek, Business Insider, and Science 2.0