The burning of the sun enlivens the starry sky and makes life settle down on the earth. Sunlight is the main source of the earth's energy and the light of life on which the earth's life depends. The fossil energy sources such as oil, natural gas and coal existing on the earth all come from the selfless gift of the sun. The sun began to shine on this star field 4.6 billion years ago, and it is still shining today. There is a brain hole here. Why hasn't the sun burned out after 4.6 billion years?
Oriental sunrise
Since ancient times, people have been chasing the sun, because the sun has brought vitality to the world and driven away cold nights. At that time, people did not understand what the sun was, but this did not prevent people from loving it, praising it and deifying it. In ancient times, our ancestors thought that the sun was a burning three-legged sun. They live in the holy hibiscus tree in Tanggu, get up from the hibiscus tree in the morning and go back to the tree to rest at night.
In the ancient Sanxingdui civilization, there is also a legend of the sun god bird. People regard it as a god, hold sacrifices for it to please it, praise it, and hope to get shelter. War is invincible, and farming is fruitful.
In European and Greek mythology, the sun is an anthropomorphic god. First Helius, then Apollo. They rode a golden sun chariot pulled by four fine horses, from east to west, from morning till night, bringing light to the world and driving away disease and cold. In Egyptian and Mayan mythology, the sun god is the creator god. The sun created everything in the world and is the master of everything. Humans are the children of the sun god, so they are protected by him and become the masters of the earth. This is the myth era, people's cognition and awe of the sun.
From the Xia, Shang and Zhou Dynasties, China began to observe the sun to guide agricultural production, compile calendars and calculate time. With such a simple wish, the country set up a special historian and began to observe the sun. China's classic Shangshu recorded a solar eclipse in the Xia Dynasty. The ancient Han Dynasty book "Five Elements" records: "The sunrise is yellow, and there is black gas as big as money, which lives in the center of Japan." This is the earliest sunspot phenomenon observed by human beings. In Europe, sunspots were discovered through telescopes in 1605.
The classic "Shuo Wen Jie Zi" of Han Dynasty explains the sun in this way. He said: "The sun is real, and the essence of great changes is inescapable, coming from a hieroglyph. Every day belongs to the sun. Ancient Japanese hieroglyphics. " Human understanding of the sun is a glowing fireball, which rises from the horizon during the day and falls into the sea at night. Man has deified the sun for a long time. Especially in Greece and other places, people built huge statues and magnificent palaces for the sun god, and even sent god officials and maids to serve the gods in the palaces, which was very pious.
The sun not only brings light to the world, but also calculates our time by observing its position. The ancients in China divided a day into 12 hours according to the location of Tao Yang, and built a sundial to know the time. In some European countries, there are also buildings similar to sundials that show time. For example, Stonehenge in Britain can accurately indicate the direction of winter solstice or summer solstice, Mayan stone pillars can indicate the time of day, and Elborgh Pyramid in Mexico can accurately indicate the time of vernal equinox and autumnal equinox.
The origin of the sun
Before 1000 BC, the Babylonians living in Mesopotamia began to think about what the sun was in the sky. In persistent observation, the neck is almost broken, and they found that the sun is a star that moves irregularly around the ecliptic. Hundreds of years later, time jumped to the ancient Greek era, and a famous philosopher explained the sun like this. He concluded that the sun is a flaming metal ball, which is bigger than the golden chariot of the legendary sun god Helius.
In the 3rd century BC, Aristakes, an ancient Greek philosopher and astronomer, put forward the theory that the sun is the center of the universe and the earth revolves around the sun, but this theory has not been recognized by mainstream people including Aristotle. It was not until16th century that Copernicus established a complete Heliocentrism system, and under the development of Bruni, it became a prominent school in the European world.
/kloc-in the 0/7th century, the invention of the telescope enabled astronomers to observe the sun more intuitively. 1609, Galileo observed the sunspot phenomenon in the telescope, and the mysterious sun finally unveiled the corner of the veil. Since then, people have discovered the sun like crucian carp crossing the river, and there are countless. 185 1 year, the first photo of the corona was taken during the solar eclipse. Solar flare was discovered in 1859.
Fast forward to the early days of modern science, people are no longer limited to observing the sun, but begin to think about how the sun is formed, where its great energy comes from and how it shines on the world. Sir Kelvin, a famous astronomer, put forward a bold hypothesis. He thinks that the sun is a rapidly cooling water polo, and the light and heat emitted now are the heat energy stored in the center of the sphere. However, this assumption was soon broken and replaced by Joseph Charles Francis Rock's meteorite theory.
It was not until 1904 that Rutherford put forward a hypothesis with a wide audience and a solid theoretical foundation. This hypothesis holds that the light and heat output by the sun come from internal heat sources, and suggests that it may be the energy provided by radioactive decay of internal heat sources. 1920, astronomer Sir Arthur Eddington further proposed on the basis of Rutherford that the temperature and pressure of the sun's core caused nuclear fusion to convert hydrogen into helium core, thus generating energy.
Astrophysicist Gaposchkin confirmed that hydrogen was dominant in the solar system five years later. 1938, astrophysicist hans bethe proposed two nuclear reaction processes, proton-proton chain reaction and carbon-nitrogen-oxygen cycle, and expounded the energy mechanism of the sun. In the mid-20th century, Einstein's mass-energy equation E = MC 2 proved that the energy of the sun comes from the internal nuclear fusion reaction.
The fusion reaction of the sun
The sun is the center of the solar system, and its surface is intertwined with hot plasma and magnetic field, and its temperature is very high. Its diameter is about 65,438+0,392,000 (65,438+0.392,65,438+006) km, which is 65,438+009 times the diameter of the earth, and its mass is 2,654,38+0030 kg, which is about 33% of the mass of the earth. 86%。 Among the chemical elements of the sun, hydrogen has the absolute upper hand. About 3/4 of the whole sun is hydrogen, helium accounts for about14, and the rest includes oxygen, carbon, iron and other elements, less than 2%.
As mentioned above, the energy of the sun comes from the internal nuclear fusion reaction. The density of matter in the sun is as high as 150 g/cm3, and the temperature is close to13.6 million k, where nuclear fusion reaction has been going on. About 9.2 1037 proton-proton chain reactions (a kind of nuclear fusion) will be carried out every second, and 620 million tons of hydrogen will be consumed to fuse hydrogen atoms into helium nuclei.
In this reaction, four hydrogen nuclei are transformed into helium nuclei under the action of high temperature and high pressure, and about 3.7 1038 protons are transformed into helium nuclei per second, which is equivalent to about 6.2101kg per second. Every time a hydrogen nucleus polymerizes into helium, about 0.7% of its mass will be converted into energy, which means that once the sun is converted, it will lose 0.7% of its mass. Therefore, the sun consumes 4.26 million tons of mass per second and releases 3.846 1026 W of energy, which is equivalent to generating 9.1921kloc-0/00000 tons of TNT explosive explosion energy per second.
According to astronomers' prediction of the age of the sun, it is about 4.6 billion years old, with an average of 3.7 fusion reactions 1038 per second, and a loss of mass of 0.7%X3.7 1038 per second. In 46 billion years, the mass of the earth exceeded 100. But the mass of the sun is originally 333000 times that of the earth, so the loss of 100 of the earth is just sprinkling water, so don't worry that the sun will burn out.
Why didn't the sun burn out?
This is because the sun does not use all the energy in the nuclear fusion reaction, and the nuclear fusion of the sun only takes place in the core of the sun. Only there can all the conditions of nuclear fusion reaction be met. Some people may ask, since such intense nuclear fusion is taking place inside the sun all the time, the energy generated is equivalent to a nuclear bomb that exploded over Hiroshima, why can the sun still exist?
This is because the interaction of forces keeps the sun in dynamic balance and stable state. The energy produced by solar nuclear fusion is from the inside out, which is just offset by the gravity of the stars. This is one of the reasons why the sun doesn't explode. However, the burning of the sun is not eternal. Scientists predict that the life span of the sun will be 50 years. After 50 years, the sun will burn faster because of the violent nuclear reaction, and eventually all the hydrogen atoms in it will be consumed, and eventually it will become an expanding red giant.
The application of the sun
The sun is the source of human life, and all living things on the earth are inseparable from the sun. Atmospheric circulation, photosynthesis, alternation of day and night, and rotation of four seasons are all the functions of the sun. For astronomers, by studying the sun, we can know the evolution of the universe and the earth, understand the formation of the earth, and lay a solid foundation for us to study other planets.
The first is the solar generator, which uses solar energy to generate electricity on a large scale. There are two main conversion methods, one is from light-heat-electricity conversion, that is, using the heat energy emitted by solar radiation to generate electricity. The process of power generation is as follows: first, the solar collector absorbs the heat carried by the sun and converts it into steam, and then the steam drives the steam turbine to drive the engine to generate electricity. The other is the direct conversion from light to electricity in one step. Its principle is to use photovoltaic vodka effect to directly convert solar radiation into electric energy, mainly using solar cells for conversion.
The second is the photothermal utilization of solar energy. Its basic principle is to collect the heat energy generated by solar radiation and then convert it into other energy for utilization. According to the different uses and temperatures, solar photothermal utilization can be divided into low-temperature utilization (800 degrees). Among them, low-temperature utilization is more, such as common solar water heaters, solar charging treasures and solar air conditioners.
Sunlight is an important prerequisite for photosynthesis of plants, so the application prospect of solar energy in biological field is very broad. Solar energy can be transformed into biomass through the illumination and action of plants. At present, the main applications are fast-growing plants, oil crops and
As a symbol of light, the sun has been pursued tirelessly for thousands of years just to see its true face. With the development of modern science, our dream has come true. We know the origin of the sun and that the sun is not a burning three-legged sun. The heat and light of the sun come from the internal fusion reaction. Since the birth of mankind, the sun has been guiding the direction of mankind, and it will still guide us as a beacon of mankind in the sea of stars.