====== Sun's coronal heating problem ======

The Sun's outer corona - stretching millions of kilometers out into space from the surface -  reaches temperatures of up to 4 million °C.. This contrasts sharply with the //surface// of the sun which has been measured at around 6 thousand °C.

A number of possible mechanisms have been proposed to explain why it's so hot. They include:

  * Slow and fast magneto-acoustic surface waves 
  * Current (or magnetic field) dissipation
  * Microflares/transients
  * Mass/particle flows
  * Magnetic flux emergence
  * //Alfvén //body wave heating
  * Magnetic re-connections
  * 'Spicule' conduction

As yet, none has been definitely confirmed as the cause. See [[https://en.wikipedia.org/wiki/Stellar_corona#Coronal_heating_problem|Wikipedia]] for details.

Further reading [[http://solar-center.stanford.edu/FAQ/Qcorona.html|Stanford Solar Center]]

//Note:// In 1997 the Goddard Space Flight Center issued a [[http://soi.stanford.edu/press/ssu11-97/ssu.html|press release]] regarding a new 'Magnetic Carpet' theory.

----

Also see : [[content:physics:cosmology:solar_spicules]]

~~stars>2/5~~