![]() The neutrinos released during the fusion reactions in the core radiate straight out of the sun because the plasma, though very dense, is almost completely transparent to them. In some regions of the sun's interior, convective cells get set up which actively transport hot matter up out of the core towards the surface and on the way, the hot matter gets mixed and equilibrates with the photons it encounters and so that energy also shows up in the temperature of the outermost parts of the sun. The energetic neutrons that the fusion reactions also emit are similarly scattered off the ions in the plasma and thereby heat the plasma too. The gammas are thus converted into visible light, IR, and UV photons. In rattling around like that, the radiation comes into thermal equilibrium with the ions it scatters off of and assumes a blackbody-shaped wavelength distribution. The scattering events are so frequent that it takes a time scale of order ~thousands of years for a photon to rattle its way all the way out to where it can escape into space without further scatterings. The gamma rays released deep in the core of a star are scattered off of ionized atoms there, which adds energy to the atoms and removes it from the photons. Is it because the radiation from the core is absorbed by the photosphere, and then being re-emitted as blackbody radiation? Or is it because of something else? I am probably stupid for not figuring out how these two explanations of the energy are consistent, but apparently I can't and I need help. But as explained in the first paragraph, the energy actually comes from nuclear fusion deep in the core. This law is a consequence of blackbody radiation theory, and so by using this law, we're now assuming that the sun's energy comes from the thermal motion of the particles in the photosphere. The electromagnetic radiation produced slowly travels upwards, while constantly being absorbed and re-emitted by the charged ions, until it reaches the photosphere, where it can basically travel freely (because there are less charged ions), until it travels out into space and then into our eyes.īut I just realized that this doesn't seem to be consistent with the exercise where we calculate the surface temperature of the sun using the Stefan-Boltzmann law. ![]() ![]() We all know that the sun generates its energy from nuclear fusion in the core.
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