The Sun's atmosphere, also known as the solar corona, is known to be extremely hot, much hotter than the Sun's surface. What is the plasma density in the solar corona?


1 Answer 1


It depends on which region you consider. The lower corona has a plasma number density of the order of $10^9 cm^{-3}$, the upper corona about $10^5 cm^{-3}$. This is all quite variable though, depending for instance on the solar activity.

Theoretically, the corona is still quite poorly understood, so its physical parameters can generally only be estimated from observations. Various methods have been employed, as for instance described in these papers involving white light observations, ultraviolet light observations, or radio obervations.

  • $\begingroup$ Thanks for your answer but I'm interested in knowing that how can one measure these densities? Any mathematical or analytical solution? $\endgroup$ Commented Jan 6, 2022 at 14:09
  • 1
    $\begingroup$ @JunaidIhsan Please see my edited answer $\endgroup$
    – Thomas
    Commented Jan 6, 2022 at 14:48
  • $\begingroup$ Is this particles per cubic centimetre, or what unit do we have here? $\endgroup$ Commented Jan 6, 2022 at 23:12
  • $\begingroup$ @PaŭloEbermann Yes, it is particles per cubic centimetre. $\endgroup$
    – Thomas
    Commented Jan 7, 2022 at 8:07

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