Can our Sun's magnetic field strengthen in any way in a short period? Can the Sun pull anything trapped in close orbit around it? What would happen if an object in orbit passes over a sunspot for example?

  • $\begingroup$ According to this recent answer the total magnetic force between the Sun and the Earth (which has a stronger magnetic field than any measly asteroid) is only 5.4 newtons. $\endgroup$ – PM 2Ring Mar 12 '19 at 22:39
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    $\begingroup$ A magnetar cannot rip iron out of planets in orbit. They'd need to be much closer than any planet could orbit. Well inside the Roche limit, so the gravity would tear the planets apart before the magnetic field would. Question on magnetars is addressed here: physics.stackexchange.com/questions/421517/… $\endgroup$ – userLTK Mar 13 '19 at 2:38
  • $\begingroup$ @userLTK revised $\endgroup$ – Muze Mar 13 '19 at 4:06
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    $\begingroup$ @PM2Ring that answer is questionable, see my comment there. The physics in the other answer that provides an almost identical result is questionable in my opinion, and in the opinion of the user who wrote it. $\endgroup$ – uhoh Mar 13 '19 at 5:15
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    $\begingroup$ @Muze since you're mentioning something that doesn't seem to be scientifically possible, and you can't even remember where you heard it from, I don't think you should include it at all. Get rid of the Magnetar link too. Just ask about the sunspot and iron-rich meteors closer than Mercury. $\endgroup$ – uhoh Mar 13 '19 at 5:21

Can our Sun's magnetic field be able to pull anything out of orbit closer than Mercury if it passes over a sunspot for example?

Almost nothing orbits as close as sunspots. Sunspots are impressively large. Large enough that the Earth can pass through a sunspot. The larger ones approach the size of Jupiter, but that's still just 1/10th the diameter of the Sun. When sunspots lead to coronal mass ejections, the ejected material and the height of the storm, prior to ejection can reach higher, but the majority of sunspots extend only a fraction of 1 solar radius from the Sun's surface. That's insanely close for an orbit.

Can our Sun's magnetic field be able to pull anything out of orbit closer than Mercury if it passes over a sunspot for example?

There's three problems with this. The first problem is that the Sun's magnetic field at any reasonable distance, becomes mostly insignificant. Sunspots are local, twisted magnetic fields with little effect at high distance. Their negative and positive poles are on the surface of the sun and from Mercury distance, very close to one another. Perhaps 10 or 20 arc-minutes apart at maximum, a fraction of 1 degree. Any magnetic force at that distance would be negligible.

Another problem is that the Sun is a much more powerful gravity machine than it is a magnet. By the time you get close enough for the Sun's magnetism to have significant effect, the Sun would fill half the sky. It would be a bad day being that close to the sun. Asteroids would be vaporizing under the immense radiation. Free ions would be affected by magnetism, but the overall object would be more affected by gravity and heat from radiation.

A 3rd problem is that nearly everything in space is a weak magnet. Even Jupiter, by mass, is a relatively weak magnet. Asteroids and comets may have some natural magnetism to them, but not a lot. Planets may induce a magnetic field, but relative to their mass, it's usually insignificant. The magnetic interaction between stellar objects isn't very significant.

However, for charged particles, it's very significant and many of the particles that fly through space are charged. A charge particle is considerably affected by magnetic fields, but anything of any size, much less so.

Now, just for fun, if we were to send some neodymium magnets orbiting the sun inside the orbit of Mercury . . . . well, the heat might destroy the magnets, but lets ignore that for now. Would those theoretical, artificial magnetic satellites indicate bumps in their orbit when they flew over a sunspot? Perhaps. I think at mercury distance the effects would be pretty small.

The size of the sunspot created orbital bumps would be dependent on the strength of the magnet relative to it's mass, so Neodymium magnet satellites would be a good choice to measure sunspot driven bumps in their orbits. I can't run the math for you, but if you pick a magnet with a magnetism and a mass and an orbital distance and you define the size and power of the sunspot, maybe someone here could calculate the effect. I still think it'd be pretty tiny. When you talk about meteors, which would either be non-magnetic or weak magnets, the effect would probably be minuscule.

  • $\begingroup$ I changed the question a bit. Fell free to add anything to it you may need. $\endgroup$ – Muze Mar 13 '19 at 19:11

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