Without the Sun the life on Earth is impossible. Every second it marks out enormous amount of energy, but the surface of our planet is reached by only its billion part. All energy of the Sun proceeds from its kernel.
The sun has the layered building. In each layer there are processes allowing this star to emit energy and to support life on Earth. The sun consists generally of two elements: hydrogen and helium. There are also others, but at very small quantities. Their mass fraction does not exceed 1%.
In the center of the Sun the kernel is located. It consists of plasma which density of 150 g/cm3. Its temperature is about 15 million degrees. In a kernel there is a continuous thermonuclear reaction during which hydrogen (more precisely, its superheavy isotope - tritium) turns into helium and vice versa. As a result of such reaction the enormous amount of energy which provides course of all other processes in a star is emitted. Scientists counted that even if this reaction will unexpectedly stop, the Sun will radiate the same amount of energy one million more years.
Thermonuclear reaction can proceed only at ultrahigh values of kinetic energy of kernels of hydrogen and helium. That is why temperature in a kernel of the Sun is so high. In this case kernels of these atoms can come nearer on the distance sufficient for course of reactions, contrary to powerful forces of Coulomb pushing away. In other parts of the Sun these processes cannot be carried out as temperature in them is much less.
It is the biggest layer of the Sun stretching from external border of a kernel to a takhoklin. Its sizes are up to 70% of radius of a star. Here transfer of the energy released as a result of thermonuclear reaction to outer sheaths is carried out. This transfer is carried out by means of photons (radiation). That is why the zone is called radiant. On border of a radiant zone temperature is 2 million degrees.
It is very thin (to solar measures) the layer dividing a radiant and convective zone. Here the processes forming magnetic field of the Sun are carried out. Particles of plasma "extend" power lines of magnetic field, increasing his tension in hundreds of times.
The convective zone begins at a depth about 200 thousand kilometers from a star surface. Temperature here quite high, but already insufficient for full ionization of that insignificant part of atoms of heavy elements. All of them are present at this zone. Their existence explains opacity of the Sun. In the depth of a convective zone there is an absorption of the radiation going from the lower layers of the Sun. It heats up and convection aspires to a surface. In process of approach its temperature and density sharply falls. They make according to 5700 Calvin and 0.0000002 g/cm3. So low density allows this substance to move freely in space.