# Incomparable energy

The interior of the sun has incomparable energy, and it emits huge amounts of light and heat without stopping for a moment.

The sun is a burning huge fireball that is extremely hot (Learn about the composition and external structure of the sun). As we all know, water boils when it is heated to 100°C; when the temperature in the steelmaking furnace reaches 1000°C, the iron blocks will turn into fiery red molten iron. The temperature of the sun is much higher than the temperature in a steel furnace. The surface temperature of the sun is 5770K, or 5497°C. It can be said that whatever is there will turn into gas. The temperature inside the sun is even higher. Theoretical calculations of astrophysics tell us that at the center of the sun, the temperature is as high as 15 million to 20 million degrees Celsius, the pressure is as high as more than 34 billion megapascals, and the density is as high as 160 g/cm3. This is really an appalling world of high temperature, high pressure and high density.

The sun is the brightest star that shines into people’s eyes, and people call it “the beacon of the universe”. The scorching sun is in the sky, and the rays of light are radiating in all directions, making people dare not face it. For humans living on Earth, sunlight is the brightest of all natural light sources. So how bright is the sun? According to scientists’ calculations, the total brightness of the sun is about 2.5×1027cd. It should also be pointed out here that there is an atmosphere of more than 100 kilometers thick around the earth, which weakens the sunlight by about 20%. After correcting for the effect of atmospheric absorption, we get the true brightness of the sun to be much larger, about 3×1027cd, which is a surprisingly large astronomical number.

Since the temperature of the sun is so high and the brightness of the sun is so great, its radiant energy must also be great. Yes. On average, an area of 1m2 outside the earth’s atmosphere facing the sun receives about 1367W of solar energy per minute. This is an important number called the solar constant. On the surface, this number may seem small. But don’t forget, the sun is 150 million kilometers away from the earth, and its energy is only 1/2.2 billion to reach the earth. The energy released by the entire sun per second is extremely huge, as high as 3.865 × 1026J, which is equivalent to the energy emitted by burning 1.32 × 1016 tons of standard coal per second.

Where does the enormous energy of the sun come from? is produced by thermonuclear reactions in the core of the sun.

The structure of the core of the sun can be divided into three very broad zones: the production core area, the radiation energy transfer area and the convection area, as shown in Figure 1. The sun is actually an extremely large factory powered by nuclear energy, and hydrogen is its fuel. Deep inside the sun, nuclear reactions are constantly going on due to the extremely high temperature and the enormous pressure of the layers above. This nuclear reaction is a thermonuclear fusion reaction in which hydrogen becomes helium. Four hydrogen nuclei undergo a series of nuclear reactions and become one nitrogen nucleus, and the depleted mass is converted into energy and radiated into space. This constant thermonuclear reaction on the sun, like the explosion of a hydrogen bomb, produces enormous amounts of energy. The energy generated is equivalent to the explosion of 91 billion 1 million-ton TNT-class hydrogen bombs in 1s, with a total radiation power of 3.75 × 1026 W.