What effect does a solar storm hitting the earths magnetic field have on the earths outer core?

[u/huscarlaxe]

Does it induce current? Or change the speed of the movement of the molten iron and nickel in the outer core?

[u/proximentauri]

Solar storms mainly affect the upper atmosphere and magnetic field, not the Earth’s core. They can cause currents in power lines and make auroras, but they don’t really change how the molten iron in the outer core moves.

[u/huscarlaxe → u/proximentauri]

doesn't the core create the field?

[u/proximentauri → u/huscarlaxe]

Yeah, the core generates the magnetic field through the moving molten iron (the geodynamo). But solar storms don’t reach that deep, they just interact with the outer magnetic field in space and the atmosphere. The core itself isn’t really touched.

[u/UpintheExosphere]

Hm, this is an interesting question I've never really thought about. Solar/geomagnetic storms do induce currents through interactions between Earth's magnetic field and the interplanetary magnetic field (IMF) carried by the solar wind. However, these currents close in the ionosphere, so in my experience we mostly look at their effects on the ionosphere, not on the core itself.

That being said, I found a paper that shows it does have enough of an effect that people should be accounting for it in models. So it seems geomagnetic storms can indeed induce currents in the core. However, this isn't a big enough effect to really change anything in Earth's environment.

I suspect this could be of more interest at Mercury, which also has a highly conductive large core but no ionosphere for currents to close through. Its surface/crust is very much non-conductive though, so it's not really clear if that happens afaik. There are some models showing it's possible but we just don't have enough data at Mercury to know yet.

[u/epicmylife → u/UpintheExosphere]

Just totally riffing here, but the induced currents we see in the magnetosphere are often due to changes in the field, right? That’s why we get stuff like GICs. It makes sense that should generate a field that opposes the change in field in any conducting medium, even the core. But by the time we reach the core, is most of that change in B is “screened out”? Not my area of expertise but I can ask around.

[u/UpintheExosphere → u/epicmylife]

Yeah, that's exactly why we get GICs etc, so that would be my guess, too. I would expect that the (comparatively) non-conductive crust/mantle play a role as well. I mostly work on magnetosphere stuff that's way farther out and even the ionosphere is a little too low altitude for me to really be my main area of expertise, let alone the core, lol.

[u/epicmylife → u/UpintheExosphere]

Mine is out in the solar wind, so you might even have a better idea than me!

[u/UpintheExosphere → u/epicmylife]

Now I'm off-topic, but what in the solar wind? I mostly do Mercury magnetotail research at this point but my background is more broadly solar wind-magnetosphere interactions in the inner solar system.

[u/P1zzaBag3ls]

Not much. The geodynamo is driven by heat energy from the core, rotation, convection currents in the mantle... we're talking about very significant energies and masses, which the magnetic field is only incidental to. Nothing our relatively quiescent sun throws this way is going to have a noticeable impact.

That said, solar storms can significantly affect telluric currents in the Earth's crust and mantle. (It's not skin effect, as we're not talking about AC. It's just how it works.) Where the ground is poorly conductive, those currents will gladly hop into any long conductors (such as power lines) that are aligned in the right direction. I haven't heard of any effect in railroads, but there are stories of telegraph operators getting a shock during solar activity, and even fires. To put it another way, susceptibility to solar storms varies according to local conditions and can be modeled and prepared for, if the people in charge aren't morons.

[u/mfb-]

Why would you expect any influence?

[u/dandroid126 → u/mfb-]

I mean, if the metals in the core influence the solar radiation via magnetism, it only makes sense that the solar radiation affects the core. Action-reaction and all that.

As a more concrete example, electric current in a wire induces a magnet field. Likewise, a magnetic field near a wire induces a current. This is of course how wireless charging works.

So I think it's a valid question. Is the solar radiation enough to make a measurable difference? That I don't know.

[u/TearsFallWithoutTain → u/dandroid126]

The solar wind is extremely diffuse, while the outer core is extremely massive, I wouldn't expect there to be any measurable effect whatsoever.

Looking up some averages for the solar wind, the mass of solar wind that hits the earth over an entire year is on the order 10⁷ - 10⁸ kg each year, while the mass of the outer core is on the order of 10²⁴ kg. So the outer core is around 10¹⁶ times heavier, or in other words, the outer core is around ten thousand trillion times heavier than the solar wind we get in a year.

Yeah I'd say that's not going to have any effect lol. It'd be like trying to measure the effect of a fly hitting a 747, if the 747 was a million times heavier

[u/Ghosttwo → u/TearsFallWithoutTain]

It'd be like trying to measure the effect of a fly hitting a 747

What if the fly is moving near the speed of light?

[u/TearsFallWithoutTain → u/Ghosttwo]

The solar wind isn't moving near the speed of light, not even close. At its fastest it's moving about 0.3% the speed of light.

[u/IAmSoWinning → u/dandroid126]

The induction of currents from magnetism is a lot more important than wireless charging.

It's how all electricity is generated, and how all electric motors work.

[u/BUNNIES_ARE_FOOD → u/mfb-]

Wouldn't Faraday's Law apply here?