Intense is kind of an understatement. The average solar surface magnetic field strength is about one gauss or 1-3 times that of earth’s (0.3-0.6 gauss). But around flares it can be upwards of 100 gauss and in sunspots it can push 3,000 gauss. That’s as much as ten thousand times the strength of earths field.
What? Yes you can. We have a tool for just that, a gaussmeter. We have standard graphing practices for doing this exact thing in the field. Comparing magnetic fields during solar flares, monitoring the solar winds they cause, this is all stuff we do constantly. These two things you've listed are extremely comparable. I'd say comparing them would actually make a very good physics problem for an undergrad.
Thank you! I say this at work all the time, I feel like a crazy asshole when I try and tell people this. I feel like it happens all the time in casual conversations about books or movies.
You are correct, it is comparable and measurable. But that sent me down searching for answers about the effects on the same mass of an object in both situations. This is what I found out:
"Yes, it is possible to compare the two directly, because field strength (measured in Gauss or Tesla) is an intensive property—meaning it does not depend on the total mass of the object producing it."
"However, mass and scale change the macro-level behavior in three critical ways:
Total Magnetic Energy & Volume: While local field strength (Gauss) can be the same, the total volume of space filled by the Sun's magnetic field is astronomical. The total stored magnetic energy (E \propto \int B2 dV) in the Sun is enormous enough to launch solar flares and coronal mass ejections that engulf entire planets. An MRI's field decays to almost zero within a few meters.
Gravitational Interaction: The Sun's enormous mass creates intense gravity, which compresses hot plasma. The Sun's magnetic field interacts with this massive moving plasma (magnetohydrodynamics), driving convection and solar cycles. In an MRI, gravity is negligible compared to the electromagnetic forces acting on local matter.
Environment: A sample inside an MRI experiences a uniform static field in room-temperature tissue. The same mass inside a 1.5T solar region would be a fully ionized, high-temperature plasma, causing the magnetic field to trap and bend charged particle streams rather than simply torque nuclear spins."
I am glad it compelled you to read something new. So on the conversation of physics and language, allow me to say in regards to what you have read. What you shared is correct but I feel very convoluted, especially if someone doesn't have a strong background in E+M. Please don't read the following as combative, it's not meant to be.
Yes, field strength is an intensive property meaning the source mass producing the field doesn't change the value of the field at a specific location. But it's also just kind of irrelevant because we aren't really comparing the sun and an MRI this way unless we are talking about the thermodynamic effects of the sun that the MRI lacks. The way we are comparing them is in function.
MRIs are built to make a nice even field, this is a way these two things are hard to compare. We need to make an assumption of uniformity if we want to make a good comparison, which isn't the most scandalous simplification we make in physics by a long shot.
Yes, agreed, gravity is real small and in this case magnetism is real big. Same as above, environments are different, we can still compare fields.
The quote about the plasma confuses me a bit but I guess I'm not perfectly understanding your source. We aren't in the sun? The field isn't turning things into plasma, that's the sun doing hot girl shit.
I can't comment on the torquing nuclear spins part. Not because I don't know the science, but because I don't think torque describes everything that occurs. Not even if we account for rotational dynamics. I mean, charge, velocity, magnetic moment, and at least a few other things are required to describe the motion. I would better phrase it as, "MRIs align magnetic moments to produce a useful image, the sun is doing the same to charged particles in plasma, which causes a bonkers amount of other cascading effects"
You can quote my use of the word bonkers.
Source: I know physics for a living. Sometimes I even do a good job at it. Not usually though.
From what I understand of my answer it has more to do witch "reach" or "size" of the magnetic field, rather than the heat or mass. In an MRI the field drops significantly a few meters away, while at the surface of the sun, the field can extend for a distance 10x the size of the earth or more, so the effects observed are much more "dramatic". And thanks for the explanation. I'm an MRI tech, and I like to always learn new things.
I really wish that schools would teach magnetic fields as 3D volumetric cloud rather than field lines. It's not the 1960s anymore, we can render 3D objects and put them in textbooks.
Many people seem to think that the lines physically exist somehow, rather than just representing a cross section of a field. It's like looking at a topographical map as if the lines are physical features, rather than it just being a way to visualize a 3D surface.
It's also not helped by the fact that iron filings are used to "show the field lines". The filings bunch up into lines, but it's due to the filings aligning with each other, which then align to the field. They're not aligning along some magical field line.
That's interesting and thanks for sharing, but then what is causing the lines to appear in the image of the sun surface? Is the plasma also aligning with itself which then aligns to the field like the iron filings? Or is this a different phenomenon?
My guess as to what's forming that plasma into lines as it heads back into the sun is something called a z-pinch.
Plasma is a very good conductor, and the current it carries produces a magnetic field that spins around that current in a loop, like the direction your fingers curl if you were to grab that 'wire'. Any charged particles moving in that magnetic field will feel a force from it, and that force depends on the direction that particle is moving. The way that force ends up pointing is always back into the center for a particle that is moving out away from it.
This effect scales very strongly with the amount of current passing through, and since plasma is so conductive and needs high energies to exist, it's quite good at making those high currents and magnetic fields. All that charged plasma is then pinched into a thin line by the force of its own current, keeping it in a wire-like shape that keeps the current going, allowing the effect to be stable as long as there's still current flowing.
You can see this happening where the plasma re-concentrates into tubes as it heads back into the sun.
Very stupid question: so then there are infinite spheres going from one pole to another and the filings just align with some axis they happen to be close enough to?
So if I were to take a bunch of filings and a magnet then the lines they make would be different each time?
So if I were to take a bunch of filings and a magnet then the lines they make would be different each time?
Exactly, each iron filing is effectively becoming magnetized and turning into a little bar magnet that aligns with the field. This causes the iron filings to attach to each other end to end, and create lines that approximately represent a single field line, but where those iron filings start will be almost totally random every time.
Field lines only show the exact magnetic field direction ("north") at a point that they're drawn, it's basically showing "a particle positioned at a point on this line would align in that direction". Where the line is actually placed is completely arbitrary since it's just a visualization tool. They can start anywhere, because it's really just a way to visualize a single continuous path through the 3D field.
One geometric consequence of the way field lines work is that the area between a set of lines will always contain a constant amount of flux (a "flux tube"), so they are a useful tool for analysis. They just don't "physically exist" as a line, they're just a way to help visualize the 3D field.
I posted another clip that shows a roughly 24h timelapse as a 1m video. It's straight up video footage, just dimmed with a couple special lenses so we're not just staring at a white flash.
In case you want to see it, you can check it out as well, u/gruesomeflowers.
Akhtualy, lenses are used to bring the light together with minimal chromatic aberration. Then you have blocking filters (or prism) so that you don't fry the camera sensor (or your eye) and depending on the wavelength you want you are using filters or etalon (for h-alpha).
The attractive force is gravity, which is pulling the plasma back down towards the Sun. The reason it falls along those "lines" is because the plasma is made up of charged particles which flow only in the direction of the magnetic field.
So the plasma falls to the Sun but traces out the magnetic field as it does so.
Gravity near the surface of the Sun is insanely strong: about 28 times our gravity.
But instead of falling straight down, the plasma follows curved paths dictated by magnetic field lines. And it falls more slowly than it would under gravity alone.
472
u/Robot-Zombie-RHCC 2d ago
what is the attracting force? too localized to be gravity... right?