Some of you will immediately give the answer: "It takes about 8 minutes for the light from the Sun to reach the Earth." Everything is correct, but in order for the light to come out from the inside of the Sun and reach its outer edge it takes … 170,000 years.
Wow! They did not expect? Why so much? The sun is not so large in diameter that it is straight "hundreds of thousands of years." Let's figure it out …
The fact is that photons, particles of light, do not go directly from the Sun's core to the outside. The central part of the Sun with a radius of about 150-175 thousand km (that is, 20-25% of the radius of the Sun), in which thermonuclear reactions take place, is called the solar core. In the core, the speed of rotation of the Sun around its axis is much higher than on the surface. There is also a proton-proton thermonuclear reaction, as a result of which helium-4 is formed from four protons. At the same time, 4.26 million tons of matter are converted into radiation every second, but this value is negligible compared to the mass of the Sun.
Leaving the nucleus, they enter the zone of radiant transfer, where energy transfer is carried out by absorbing and re-emitting photons. Moreover, the absorption-emission of photons does not depend in any way on the direction in which they were directed, because of this, a multiply re-emitted photon takes a lot of time to finally break out. This journey can take millions of years. On average, this period for the Sun is 170 thousand years.
Closer to the surface of the Sun, the temperature and density of matter are no longer sufficient for the complete transfer of energy through re-radiation. Vortex mixing of the plasma occurs, and the transfer of energy to the surface (photosphere) is carried out mainly by the movements of the substance itself.
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The photosphere (the layer that emits light) forms the visible surface of the Sun. The main part of the optical (visible) radiation of the Sun emanates from the photosphere, while radiation from deeper layers no longer reaches us.