Question about planetary magnetic poles

[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!

[naita]

@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.

[psychonaut]

@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.

[naita]

@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

[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?”

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.

[psychonaut]

@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.

[Northern_Piper]

Uranus | Axial tilt

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]

[eburacum45]

@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

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…

[Exapno_Mapcase]

The sun’s magnetic field is going to flip this year. It does so regularly, much more often than earth, in fact abut every 11 years in correlation with the maximums of the sunspot cycle.

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.

[JohnGalt]

Last week’s episode of Nova, Secrets of the Sun showed a very good visual explanation of pole flipping. You can watch the whole episode at the link.

[Michael63129]

@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, 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).

[Saint_Cad]

@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.

[Chronos]

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

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.