The Sun is located 150 million kilometres away from us. This large distance is no obstacle to living beings on Earth to benefit from its warmth and light. If the Sun goes out, gives no light and warmth, then water and even air itself on the Earth would freeze, and people, animals and plants would die.

High temperature on the Sun’s surface would not only melt down iron and other metals, but also bring them into hot gaseous condition. For this reason, there is no solid and liquid substance in the Sun, just hot gases. The Sun is a large boiling sphere. Temperature at its core is much higher than on the surface. At the Sun’s core, temperature reaches 15 million degrees. Such high temperature inside the Sun existed billions of years and will exist as many. What occurs inside the Sun? Why does not this giant bonfire go out? Astronomers and physicists have long been trying to answer this question: how could the Sun keep such a high temperature billions of years? A number of scientists believe that, as a result of chemical reaction, hydrogen changes into helium. When hydrogen fuses with heavier particles, energy is generated in the form of light and warmth. The same energy, spreading into the space, reaches the Earth and bestows live upon all living beings.