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Question on positive negative magnetic fields

  1. Jul 5, 2012 #1
    1. If the sun is reversing polarity where the northern part of the sun is showing signs of becoming positive and the southern part of the sun is already positive and if two like polarities repel could not the sun ? break in two.
    2. question If the sun has two positives end and a negative polarity in the middle or if it does reverse then the southern part would become a negative polarity would the gravitational axis of earth be moved.
  2. jcsd
  3. Jul 6, 2012 #2

    Simon Bridge

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    We don't normally talk about magnetic poles being positive of negative but if I take your meaning that the current northern part of the Sn reverses it's polarity? ... well that would depend on what else is holding the Sun together ... But do you know how the solar magnetic field works? It's not actually a bar magnet.

    "Gravitational axis"? What can that mean?

    However, if I understand you properly, gravity depends on mass ... check the alignment of the various planets' magnetic fields compared with the Sun's.
  4. Jul 6, 2012 #3


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    Have no fear, the Earth is in no danger of being suddenly flipped or anything crazy. This magnetic reversal happens every decade or so. http://en.wikipedia.org/wiki/Solar_cycle
  5. Jul 6, 2012 #4
    1. A magnetic dipole can not break in an asymmetric manner. The monopole density in a finite volume of space is always zero. Therefore, there can not be an unbalanced dipole the way you envision in your example.
    What you are envisioning is the formation of a nonzero magnetic monopole moment forming in the sun. That can't happen according to the currently known laws of electrodynamics.
    The sun becomes a perfect dipole every 12 to 13 years. The dipole displays itself as two giant sunspots at the north an south spin poles of the sun, which at that time has no other sunspots. So the perfect dipole occurs during what we would call a sunspot minimum. At the sunspot minimum, there are only two sunspots on opposite sides of the sun that are at an angle where they would be hard to see from the earth.
    The magnetic behavior of the sun is consistent with the theory of electromagnetic radiation as applied to an electrically conducting gas (i.e., a plasma). Hypothetically, the two sunspots are not independent at this time. There is a tube of magnetic flux that connects the magnetic north sunspot to the magnetic south sunspot at this time. This corresponds to a hypothetically giant electric current moving around the equator of the sun. At the time of the sunspot minimum, the sun behaves very much like a bar magnet on earth.
    The giant dipole at the sunspot minimum breaks apart symmetrically. That is, the hypothetical bar magnet in the sun breaks up into a number of bar magnets. Thus, the giant sunspots on each side of the sun breaks up into equal numbers of small sunspots. Each sunspot that forms has a partner of opposite polarity on the opposite side of the sun.
    The magnetic polarity of the sun at times other than the sunspot minimum has to be described by higher order moments than dipole. The sun forms quadrupoles, octopoles, etc. However, a balance is maintained. Every magnetic north is balanced by a magnetic south.
    The monopole moment of the sun is always zero.
    2. I don't know what you mean by a gravitational axis. I will assume that you are referring to the spin axis of the earth. The spin axis of the earth is the direction of the angular momentum vector in the coordinate system of the center of the earth.
    The earth currently has a magnetic dipole that switches about once every 100 KY. The sun has a magnetic dipole that switches about once every 12 years. The two magnetic dipoles have to exert a small torque on each other, even if the torque is very small.
    Therefore, my hypothesis is that there is a very small shift on the spin axis of the earth every 12 years, corresponding to the reversal in the dipole of the sun. However, the torque exerted on the earth by the sun's dipole is very small. The moment of inertia of the earth is very large. Therefore, the shift would have to be very small. My hypothesis is that the shift of the earth axis caused by the magnetic field would be so small that we can't measure it.
    Other torques would have a much larger effect. For instance, the torque caused by the moon's gravitational field causes precession. The spin axis of the earth revolves every 25 KY due to the gravitational torque of the moon. As slow as this is, I suspect that the effect of the magnetic field of the sun on the earth would be smaller still. It would be almost impossible to isolate the small effect caused by your magnetic disturbance.
    I am not sure about the other planets. For instance, Jupiter has a much larger magnetic dipole than the earth. It is also much more massive than the earth. My suspicion is that the magnetic interaction between Jupiter and the sun may not always be negligible.
    There is a certain coincidence that I have been curious about for some time. The solar magnetic dipole cycle is about one reversal every twelve earth years. The orbital period of Jupiter around the sun is about twelve years. This looks like a very close coincidence for the two most massive and most magnetic bodies in the solar system.
    I have wondered whether the orbit of Jupiter is driving the solar magnetic cycle. If anyone has heard any theories along that line, please let us know.
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