Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is the capacitance of the sun?

  1. Oct 13, 2007 #1
    What is the capacitance of the sun? semms like a straigtforward question but I cant seem to find any information on what it is. I'm dont know if it has been measured, or if its even possible to measure, but I would have thought a body that big and active as the sun would have an ability to store a certain amount of charge. is it a net positive or negative charge?
    Last edited: Oct 13, 2007
  2. jcsd
  3. Oct 13, 2007 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    As far as we know, the net charge on the sun is about 0, i.e. it's neutral. When protons (or other positively charged nuclei) get blown away (in the solar wind or CMEs), electrons go with them.
  4. Oct 13, 2007 #3


    User Avatar

    Staff: Mentor

    Capacitance is a differential concept. The capacitance of the sun with respect to what? Pluto? Earth? All of the planets? The nearest star?
  5. Oct 14, 2007 #4
    i was wondering what the capacitance would be compared to the plasma in the solar wind at (for example) the asteroid belt. We know the solar wind is quasi-neutral but made of none-the-less of charged ions, so i am curious that if the sun does have a net charge and high voltage how this would effect charged ions in the solar wind. I know that curently we think it is neutral, but you can claim anything is neutral if you choose your own parameters, as berkeman correctly stated capacitance is a differential concept.

    Is there anyway that we can test the neutrality of the sun? or is it just asumed to be that way?

    there is a huge charge difference in Earths upper atmosphere that causes lightning to arc between the different potentials, but you can still claim the earth as a whole is completely neutral, even though a lot of charge separation is taking place on a localized scale.
    Last edited: Oct 14, 2007
  6. Oct 14, 2007 #5
    On a slightly unrelated note, I was just thinking could a net charge on the sun be the explanation for the unexpected heating of the corona? Currently there is no reason why the corona and chromosphere should be millions of degrees K hotter than the surface of the sun. But if there is an electric field just outside the sun, generated by the net charge of the sun, that would explain why the particles are getting accelerated and gain so much heat. ions would have their maximum potential energy when they are in this photospheric plasma; however their mechanical energy would be relatively low.

    At a certain point when a +ve ion randomly moves out of the photosphere and into the electric field (voltage gradient) it will result in it being accelerated outwards. The particles are basically transferring the high electrical potential energy they had in the sun into kinetic energy by gaining an extremely high outwards radial velocity, and would explain why particles in the corona are so energetic. This way the inverse square law for radiant energy is not being broken as the current model does.

    That is the only explanation I can see to explain the coronal heating problem, unless there are others I am not aware of.
    Last edited: Oct 14, 2007
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook