# Question about planetary magnetic poles
**URL:** https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612
**Category:** Factual Questions
**Created:** [May 2, 2012, 7:53am UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612 "2012-05-02T07:53:27Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@brujaja](https://boards.straightdope.com/u/brujaja)
#### Post date: [May 2, 2012, 7:53am UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/1 "2012-05-02T07:53:27Z")
I’m just wondering if it would be possible for a celestial body, especially a planet, to have magnetic poles that reverse at regular, frequent intervals? If it is possible, what kinds of effects would you expect to see?
Also, forgive me if this is an ignorant question, but is there any reason why a planet’s poles mightn’t wind up going east/west rather than (roughly) north/south, as our planet’s do?
Thanks!
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### Author:  [@naita](https://boards.straightdope.com/u/naita)
#### Post date: [May 2, 2012, 8:19am UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/2 "2012-05-02T08:19:46Z")
> [@brujaja](#):
>
> I’m just wondering if it would be possible for a celestial body, especially a planet, to have magnetic poles that reverse at regular, frequent intervals? If it is possible, what kinds of effects would you expect to see?
>
> Also, forgive me if this is an ignorant question, but is there any reason why a planet’s poles mightn’t wind up going east/west rather than (roughly) north/south, as our planet’s do?
>
> Thanks!
We don’t even/barely understand why our own poles reverse.
The effects of a pole reversal on Earth are increased cosmic and solar radiation for a period of time, and possibly a bit of confusion for animals sensing the Earth’s magnetic field. We haven’t observed a change, so we don’t know much more than that. The effects of a random extrasolar planet would be similar.
The magnetic field is related to the Earth’s rotation, so no, you can’t have it go east/west.
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### Author:  [@psychonaut](https://boards.straightdope.com/u/psychonaut)
#### Post date: [May 2, 2012, 10:07am UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/3 "2012-05-02T10:07:51Z")
> [@naita](#):
>
> The magnetic field is related to the Earth’s rotation, so no, you can’t have it go east/west.
Why not? Uranus’s magnetic field is tilted 59 degrees from its axis of rotation, so it’s closer to east–west than north–south.
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### Author:  [@naita](https://boards.straightdope.com/u/naita)
#### Post date: [May 2, 2012, 10:12am UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/4 "2012-05-02T10:12:52Z")
> [@psychonaut](#):
>
> Why not? Uranus’s magnetic field is tilted 59 degrees from its axis of rotation, so it’s closer to east–west than north–south.
I stand corrected. If you make the planet an ice giant, it seems you can have a seriously tilted magnetic field.
> [@](#):
>
> Neptune has a similarly displaced and tilted magnetic field, suggesting that this may be a common feature of ice giants. One hypothesis is that, unlike the magnetic fields of the terrestrial and gas giant planets, which are generated within their cores, the ice giants’ magnetic fields are generated by motion at relatively shallow depths, for instance, in the water–ammonia ocean.
> **[Uranus](https://en.wikipedia.org/wiki/Uranus#Magnetic_field)**
>
> Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which astronomy calls "ice" or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature (49 K (−224 °C; −371 °F)) of all the Solar System's planets. It has a marked axial tilt of 82.23° with a retrograde rotation period of 17 hours and 14 minutes. This means tha...
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### Author:  [@brujaja](https://boards.straightdope.com/u/brujaja)
#### Post date: [May 2, 2012, 12:08pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/5 "2012-05-02T12:08:41Z")
So, just out of further curiosity, is it possible for an extrasolar planet to rotate (not orbit) on the y-axis, relative to its sun? Y’know, “vertically” instead of “horizontally?”
And, one more thing – (I know I’m going pretty far out on a limb here, but-) are there any conditions that could possibly make a planet reverse its rotation at intervals – say, orbiting two suns; or a sun and another huge planet?
Thanks a lot. There’s something arcane I’m trying to figure out.
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### Author:  [@psychonaut](https://boards.straightdope.com/u/psychonaut)
#### Post date: [May 2, 2012, 12:48pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/6 "2012-05-02T12:48:08Z")
> [@brujaja](#):
>
> So, just out of further curiosity, is it possible for an extrasolar planet to rotate (not orbit) on the y-axis, relative to its sun? Y’know, “vertically” instead of “horizontally?”
Sure. Again, Uranus does this.
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### Author:  [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)
#### Post date: [May 2, 2012, 1:17pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/7 "2012-05-02T13:17:16Z")
> **[Uranus | Axial tilt](https://en.wikipedia.org/wiki/Uranus#Axial_tilt)**
>
> The Uranian axis of rotation is approximately parallel to the plane of the Solar System, with an axial tilt that can be described either as 82.23° or as 97.77°, depending on which pole is considered north.\[j\] The former follows the International Astronomical Union definition that the north pole is the pole which lies on Earth's North's side of the invariable plane of the Solar System. Uranus has retrograde rotation when defined this way. Alternatively, the convention in which a body's north and s...
> [@](#):
>
> **Axial tilt**
>
> Uranus has an axial tilt of 97.77 degrees, so its axis of rotation is approximately parallel with the plane of the Solar System. This gives it seasonal changes completely unlike those of the other major planets. Other planets can be visualized to rotate like tilted spinning tops on the plane of the Solar System, while Uranus rotates more like a tilted rolling ball. Near the time of Uranian solstices, one pole faces the Sun continuously while the other pole faces away. Only a narrow strip around the equator experiences a rapid day-night cycle, but with the Sun very low over the horizon as in the Earth’s polar regions. At the other side of Uranus’s orbit the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness.[49] Near the time of the equinoxes, the Sun faces the equator of Uranus giving a period of day-night cycles similar to those seen on most of the other planets. Uranus reached its most recent equinox on December 7, 2007.[50][51]
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### Author:  [@eburacum45](https://boards.straightdope.com/u/eburacum45)
#### Post date: [May 2, 2012, 4:30pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/8 "2012-05-02T16:30:11Z")
> [@brujaja](#):
>
> And, one more thing – (I know I’m going pretty far out on a limb here, but-) are there any conditions that could possibly make a planet reverse its rotation at intervals – say, orbiting two suns; or a sun and another huge planet?
This depends on exactly what you mean, but if you mean a ‘figure-of-eight’ orbit around two stars, or around a star and a giant planet, no, this is unlikely as it is very unstable. If a planet ever found itself in such an orbit it would fairly quickly migrate one way or another so it was orbiting one star or planet, or in an ellipse around both.
One interesting possibility is a so-called _horseshoe orbit_, where a smaller object is in a harmonic relationship with a larger object.
> **[Horseshoe orbit](https://en.wikipedia.org/wiki/Horseshoe_orbit)**
>
> In celestial mechanics, a horseshoe orbit is a type of co-orbital motion of a small orbiting body relative to a larger orbiting body. The osculating (instantaneous) orbital period of the smaller body remains very near that of the larger body, and if its orbit is a little more eccentric than that of the larger body, during every period it appears to trace an ellipse around a point on the larger object's orbit.
> However, the loop is not closed but drifts forward or backward so that the point it circ...
The smaller object _appears_ to reverse direction as seen from the larger object, and vice versa; but seen from other refernce frames it just keeps going in the same direction (but at different speeds).
Confused? I am…
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [May 2, 2012, 5:15pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/9 "2012-05-02T17:15:53Z")
The sun’s magnetic field is going to flip [this year](http://www.dailygalaxy.com/my_weblog/2012/04/the-great-switch-suns-magnetic-field-does-a-complete-reverse-every-11-years.html). It does so regularly, much more often than earth, in fact abut every 11 years in correlation with the [maximums of the sunspot cycle](http://science.nasa.gov/science-news/science-at-nasa/2001/ast15feb_1/).
You must have lived through several of these and not noticed. There are effects on the earth, from temperature to disruption of GPS to auroras and more, but nothing major.
The earth will go through another reversal of its own magnetic field probably sometime soon. They happen more irregularly and also cause disruption, especially to animals that depend on the fields to travel and because the fields shield us from solar winds. But these aren’t extinction-level problems. In geologic terms, magnetic field reversals are no big deal.
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### Author:  [@JohnGalt](https://boards.straightdope.com/u/JohnGalt)
#### Post date: [May 2, 2012, 5:38pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/10 "2012-05-02T17:38:14Z")
Last week’s episode of Nova, [Secrets of the Sun](http://www.pbs.org/wgbh/nova/space/secrets-sun.html) showed a very good visual explanation of pole flipping. You can watch the whole episode at the link.
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### Author:  [@Michael63129](https://boards.straightdope.com/u/Michael63129)
#### Post date: [May 2, 2012, 6:14pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/11 "2012-05-02T18:14:17Z")
> [@brujaja](#):
>
> I’m just wondering if it would be possible for a celestial body, especially a planet, to have magnetic poles that reverse at regular, frequent intervals? If it is possible, what kinds of effects would you expect to see?
[Earth undergoes magnetic reversals all the time](http://en.wikipedia.org/wiki/Geomagnetic_reversal), geologically speaking; there is evidence for at least several hundred such reversals. Nothing spectacular happens either during those times, as far as we can tell (humans/human ancestors have already experienced several, the last being 780,000 years ago, albeit not with modern technology which could be affected, like compasses, though that wouldn’t cause much problems).
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### Author:  [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)
#### Post date: [May 2, 2012, 6:26pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/12 "2012-05-02T18:26:20Z")
> [@naita](#):
>
> We don’t even/barely understand why our own poles reverse.
>
> The effects of a pole reversal on Earth are increased cosmic and solar radiation for a period of time, and possibly a bit of confusion for animals sensing the Earth’s magnetic field. We haven’t observed a change, so we don’t know much more than that. The effects of a random extrasolar planet would be similar.
>
> The magnetic field is related to the Earth’s rotation, so no, you can’t have it go east/west.
And Jupiter’s is a quadripole so the poles are at 45 degrees to the axis of rotation.
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### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [May 2, 2012, 7:39pm UTC](https://boards.straightdope.com/t/question-about-planetary-magnetic-poles/620612/13 "2012-05-02T19:39:36Z")
> [@](#):
>
> One interesting possibility is a so-called horseshoe orbit, where a smaller object is in a harmonic relationship with a larger object.
> [Horseshoe orbit - Wikipedia](http://en.wikipedia.org/wiki/Horseshoe_orbit)
Not necessarily different-sized objects: Saturn’s moons Janus and Epimetheus are in a similar arrangement, despite being comparable in size.
And **Saint Cad** , Jupiter’s field is, in general, a dipole. Like the Sun, it could have a significant quadrupole moment during reversals, but that’s not the normal state of affairs, and even having a quadrupole moment doesn’t necessarily imply that it has four poles arranged around the corners of a square.