brief introduction
sun
The sun is an ordinary star in the Milky Way. The average distance from the earth is 1.496 million km, the diameter is 1.39 million km, the average density is 1.409 g/,the mass is 1.989× 1.33 g, and the surface temperature is 5770 Kelvin. From inside to outside, there are the nuclear reaction area of the sun, the troposphere of the sun and the atmosphere of the sun. Thermonuclear reactions continue in its central region, and the energy generated is emitted into space by radiation. One of the 2.2 billion energies radiates to the earth and becomes the main source of light and heat on the earth. Stars also have their own life history, from birth, growth to aging and finally to death. They are different in size, color and evolution. The connection between a star and life is not only that it provides light and heat. In fact, the heavy atoms that make up planets and living matter are produced in the process of explosions at the end of some stars' lives.
The age of the sun is about 4.6 billion years, and it can still burn for about 5 billion years. In the last stage of its existence, helium in the sun will be transformed into heavy elements, and the volume of the sun will begin to expand until it engulfs the earth. After the red giant stage of 1 100 million years, the sun will suddenly collapse into a white dwarf-the last stage of the existence of all stars. After trillions of years, it will eventually completely cool down and then slowly disappear into the darkness.
physical parameter
solar wind
Radius: 696,295 kilometers.
Mass:1.989×1030kg
Temperature: 5800℃ (surface) 1560000℃ (core)
Total radiation power: 3.83× 1026 joules per second.
Average density:1.409g/cm3.
Average distance between the sun and the earth:1.500 million kilometers.
Age: about 5 billion years.
Solar radiation energy reaching the upper limit of the earth's atmosphere is called astronomical solar radiation. When the earth is located at the average distance between the sun and the earth, the total energy of the whole spectrum of solar radiation received by the unit area where the upper boundary of the earth's atmosphere is perpendicular to the solar rays in unit time is called the solar constant. The common unit of solar constant is watt/square meter. Due to different observation methods and techniques, the obtained solar constant values are also different. The solar constant published by the World Meteorological Organization (WMO) at 198 1 is 1368 W/m2. More than 99% of the solar radiation spectrum in the upper atmosphere of the earth is between 0.15 and 4.0 microns. About 50% of solar radiation energy is in the visible spectrum (wavelength 0.4 ~ 0.76 micron), 7% is in the ultraviolet spectrum (wavelength 0.76 micron), and the maximum energy is in the wavelength 0.475 micron. Because the wavelength of solar radiation is far less than that of ground and atmospheric radiation (about 3 ~ 120 micron), it is usually called short-wave radiation, and ground and atmospheric radiation is called.
Long wave radiation. Solar activity and changes in the distance between the sun and the earth will cause changes in the upper limit of solar radiation energy in the earth's atmosphere.
sun spot
The sun is an ordinary star, and it has spent about half of its main sequence career on the Herro diagram. It is a hot gas (strictly speaking, plasma) ball with a mass of 1989 100 billion tons (about 330,000 times the mass of the earth) and a diameter of1392,000 kilometers (about 109 times the diameter of the earth). Its average density is 1.4 times that of water, but this average density implies a wide density range, from the ultra-high density core to the thin outer layer.
As a stellar sun, its overall appearance is luminosity of 38.3 billion watts and absolute magnitude of 4.8. It is a yellow G2 dwarf with an effective temperature of 5800 Kelvin. The average distance between the sun and the earth around it is 149597870km(499.005 light seconds or 1 astronomical unit). By mass, its material composition is 7 1% hydrogen, 26% helium and a small amount of heavy elements. The angular diameter of the circular surface of the sun in the sky is 32 minutes, which is very close to the angular diameter of the moon as seen from the earth. This is a wonderful coincidence (the diameter of the sun is about 400 times that of the moon, and the distance from us is just 400 times that of the earth and the moon), which makes the eclipse look particularly spectacular. Because the sun is much closer to us than other stars, its apparent magnitude reaches -26.8, making it the brightest celestial body on earth. The sun rotates once every 25.4 days (average period; The equator rotates faster than high latitudes) and revolves around the center of the Milky Way every 200 million years. The sun is slightly flattened due to its rotation, which is 0.00 1% different from the perfect sphere, which is equivalent to a difference of 6km between the equatorial radius and the polar radius (the earth is 2 1km, the moon is 9km, Jupiter is 9000km, and Saturn is 5500km). Although the difference is small, it is important to measure this flatness, because any slightly larger flatness (even 0.005%) will change the influence of solar gravity on Mercury's orbit, making the test of general relativity based on Mercury's perihelion precession unreliable.
The structural composition is about 7 1% hydrogen, 27% helium and 2% other elements.
From the center to the outside, the sun can be divided into nuclear reaction area, radiation zone, troposphere and atmosphere. Due to the poor transparency of the gas in the outer layer of the sun, what humans can directly observe is the solar atmosphere, which is divided into three layers from the inside out: the photosphere, the chromosphere and the corona.
Photosphere: Another famous activity phenomenon on the surface of the photosphere is sunspots. Sunspots are huge air swirls on the photosphere, most of which are nearly oval, which are darker against the bright photosphere background, but in fact their temperature is as high as 4000℃. If the sunspot can be taken out alone, a large sunspot can emit the light equivalent to a full moon. The appearance of sunspots on the surface of the sun is constantly changing, reflecting the change of solar radiation energy. The change of sunspots has complex periodicity, and the average activity period is 1 1.2 years.
Chromosphere: The atmosphere directly above the photosphere is called chromosphere, which is not easy to be observed at ordinary times. In the past, this area was only visible during a total solar eclipse. When the moon hides the bright brilliance of the ball of light, people can find that there is a rosy brilliance on the edge of sun gear, that is, the ball of color. Chromosphere is about 8,000 kilometers thick, and its chemical composition is basically the same as that of the photosphere, but the density and pressure of matter in chromosphere are much lower than that of the photosphere. In daily life, the farther away from the heat source, the lower the temperature, but in the solar atmosphere, the opposite is true. The temperature at the top of the photosphere near chromosphere is almost 4300℃, but it reaches tens of thousands of degrees at the top of chromosphere, and then rises to several million degrees in the corona. People are puzzled by this abnormal warming phenomenon, and the exact reason has not been found so far.
Prominence: People can also see many soaring flames on the chromosphere, which is the so-called "prominence" in astronomy. Prominence is a rapidly changing activity phenomenon, and a complete prominence process usually takes dozens of minutes. At the same time, the shape of prominence can be said to be varied, some like clouds, some like waterfalls and fountains, some like curved arch bridges, some like grass, and the list goes on. Astronomers classify prominences into three types according to the size and speed of morphological changes: quiet prominences, active prominences and explosive prominences. The most spectacular is the explosive prominence, which is quiet or active. Sometimes, it will suddenly become "violent", desperately throwing gas up, and then turning back to the surface of the sun to form a ring, so it is also called an annular prominence.
Corona: The corona extends over the chromosphere and extends to several solar radii. The material in the corona is thinner, which will expand outward and make thermoelectric gas particles flow out of the sun continuously, forming the solar wind.
Sunspot: Observing the sun through a general optical telescope, what is observed is the activity of the photosphere (the innermost layer of the solar atmosphere). You can often see many black spots on the photosphere, called sunspots. The size, number, location and shape of sunspots on the sun's surface are different every day. Sunspot is a local strong magnetic field formed by the violent movement of photosphere, and it is an important symbol of photosphere activity. Long-term observation of sunspots will show that there are many sunspots in some years, few sunspots in some years, and sometimes there are no sunspots in the sun for several days or dozens of days. Astronomers have long noticed that there is an interval of 1 1 year from the year with the most (or least) sunspots to the next year with the most (or least) sunspots. In other words, the average activity period of sunspots is 1 1, which is also the activity period of the whole sun. Astronomers call the darkest year of the sun "the peak year of solar activity" and the year with the least sunspots "the quiet year of solar activity".
The satellite of the sun
Satellites are celestial bodies orbiting planets. Satellites are divided into natural satellites and artificial satellites, of which Jupiter has the most natural satellites. In the solar system, all planets except Mercury and Venus have natural satellites. Planetary gas and dust will collide and merge. In addition to natural satellites, there are asteroids, comets and so on.
Two Mars satellites were discovered by Hall at the Naval Observatory. Previous observations failed to find them because the two satellites were unusually small. Hall called the outer satellite Phobos and the inner satellite Phobos.
Jupiter is a planet with many satellites in the solar system. Jupiter's satellites are numbered in the order of discovery. 16 10, Galileo observed four satellites with his own astronomical telescope. Astronomers named these four satellites Galileo satellites to commemorate this great discovery of Galileo. The four satellites are Eo, Europa, Garimei and callisto from the inside out. They are called io, Europa, Ganymede and Callisto for short, and their surface characteristics are quite different. Io is the most frequent and intense volcanic activity observed in the solar system so far, which provides new enlightenment for astronomers to study solar system celestial bodies. Europa is smaller than the moon, but its density is similar to that of the moon. Ganymede is Jupiter's largest satellite. The surface of Callisto is covered with many stone pits.
Jupiter's moons have various forms. Titan, the most famous satellite, has an atmosphere, which is the only celestial body with an atmosphere among the solar system satellites discovered so far. Saturn is the planet with the largest number of satellites in the solar system. There are many large and small satellites around it, just like a family. So far, a * * * has found 23.
Uranus is different from other celestial bodies in the solar system. The moons of Uranus are not named after the characters in ancient mythology, but after the characters in Shakespeare and the Pope. Uranus also has many satellites, including a very large satellite with a diameter of 470 kilometers.
Neptune is a light blue planet orbiting the sun and a typical gaseous planet. Neptune has eight satellites. It used to be thought that Neptune had only two moons, Triton and Triton. Six smaller satellites were discovered through exploration, so that Neptune's satellites reached eight.
The satellite Chalong accounts for more than half of Pluto's size. Pluto is only 20,000 kilometers away from the satellite Chalong. Period of revolution of Pluto is the same as period of revolution of Chalong.
Legend of the sun
Legend of the sun
Greek sun myth
Apollo, the sun god, was the son of Zeus and Leto. Hera, the queen of God, was jealous of the love between Zeus and Leto and brutally persecuted Leto, making her wander around. Finally, Leto was taken in by a floating island named Delos, where she gave birth to the sun god and the moon god with difficulty. So Hera sent Python Pito to kill Leto's mother and son, but it didn't work. Later, Leto's mother and son were lucky. Hera was no longer their enemy, and they returned to the ranks of God. In order to avenge his mother, Apollo shot Pito, a python that brought infinite disaster to mankind, with his own arrow, so as to save the people from harm. Apollo was very proud after killing the python. When I met eros Jr., the god of love, I laughed at his little arrow for its powerlessness, so eros hit Apollo with an arrow burning with the flame of love, and hit Daphne, the fairy, with an arrow that could dispel the spark of love, making them miserable. In order to get rid of the pursuit of Apollo, Daphne asked her father to turn herself into a laurel tree. I didn't expect Apollo to still have a crush on her, which moved Daphne very much. After that, Apollo used laurel as an ornament, and laurel became a symbol of victory and honor. Every day at dawn, Apollo, the sun god, will board the golden chariot of the sun, pull up the reins and hold high the whip to patrol the earth, bringing light and warmth to mankind. Therefore, people regard the sun as a symbol of light and life.
Nordic sun myth
Frey is the god of abundance, prosperity, love and peace, and also the king of Alfei, a beautiful fairy tale country. He and Walder are both gods of light, or sun. His elves do good deeds all over the world. He often rides a wild boar with a golden mane to go out for inspection. Everyone enjoys the peace and happiness he gives. He has a sword, which is radiant and can walk on clouds. He also has a pocket magic ship, which can carry all the gods and their weapons when necessary.
China sun myth
Houyi shot down nine suns.
According to legend, in ancient times, the king of a poor country in Xia Dynasty was a handsome man named Hou Yi. That Hou Yi is not only handsome, but also both civil and military. He knows astronomy above and geography below, and is good at strategy and martial arts, especially archery. Under the wise management of Hou Yi, some poor countries are thriving and arrogant everywhere. People have plenty of food and clothing, live and work in peace and contentment, work at sunrise and rest at sunset, showing a scene of prosperity and peace.
After dealing with state affairs every day, Hou Yi took his beloved bow and arrow (I heard that this arrow was given by the gods) to practice at the archery range, day after day, year after year, without interruption. His archery has reached an unparalleled level.
The days passed in peace and happiness, and some poor countries became more and more prosperous. Just as people were immersed in happiness and satisfaction, suddenly, disaster fell from the sky.
It was a midsummer day, and that morning was no different from before, but at sunrise, ten suns rose in the east at the same time. People looked at everything in front of them, dumbfounded. Everyone knows what it means to have ten suns in the sky. Immediately, there were cries and prayers. People tried every means to ask God for mercy and take back the extra nine suns, but to no avail. Day after day, the crops in the field gradually withered, the water in the river slowly dried up, and the old, the weak and the sick fell down one after another ... Hou Yi looked at everything in front of him, his heart ached, but he could do nothing. He is heartbroken and anxious, and people are getting thinner. One day, just after he closed his eyes, he suddenly dreamed of an old man with a white beard. The old man taught him how to make nine arrows into the shape of the sun and aim them at the bull's-eye every day. After practicing for 7749 days, he was able to shoot down the sun in the sky and told him not to make it public until the fiftieth day. Hou Yi opened his eyes and was surprised. He immediately began to make an arrow target. After shooting the target, he hid in the mountains with an arrow and practiced day and night. On the fiftieth day, after the news that the king was going to shoot the sun came out, the spirits of people struggling with death suddenly cheered up, as if they saw the hope of life. People are afraid that Houyi's arrow will not fall in the sun, and men, women and children will bear the blazing sun. In the shortest time, they will erect a tower several meters high and carry drums to cheer for Houyi. In the deafening drums, Hou Yi stepped onto the balcony step by step. Behind him are countless pairs of eager and expectant eyes. Around him, there is a land of pain and groaning. Above his head, there is a hot and expanding sun. He told himself that he could only succeed, not fail. Although he knew that he was taking a road of no return, he had no regrets in order to save the suffering people.
Finally, when he reached the top of the building, Hou Yi looked back at his subjects and his palace for the last time, then raised his head, raised his arrow and slowly pulled open the bow. With a whoosh, I heard a loud noise, and the hit Sun fell down and disappeared. The audience cheered, and shouts and drums resounded through the sky. Hou Yi drew his bow again and again, and shot seven more. There are only two left. He was exhausted at this time, but he knew that there was only one sun left in the sky. If he gives up at this time, it means that all previous efforts have been in vain. He raised his arrow again and shot down the ninth sun with all his strength, then fell to the ground and never got up again. Everything was restored to its original state, but the brave and respectable Hou Yi closed his eyes forever. ...
The nine suns that were shot fell in nine different places. One of them fell into the Yellow Sea and smashed a lake, which was later called Sheyang Lake. Soon, a river called Sheyang River flowed out of Sheyang Lake.
Myths and legends about the sun in Shan Hai Jing
In the far southeast overseas, there is a country called He. There is an unusually beautiful woman in the country named He. She washes the sun in Gan Yuan every day. The sun will be polluted after dark. After he finished washing, the polluted sun will still be as bright as before when it rises the next day. This one is actually the wife of the legendary ancient emperor. She gave birth to ten suns and let them take turns to be on duty in the air, sending light and warmth to the world. The starting point of these ten suns is desolate and remote. There is a mountain in that place. There is a hibiscus tree on the mountain, 300 miles high, but its leaves are as big as mustard seeds. There is a deep valley under the tree called Tanggu, where the sun bathes. When they finished taking a bath, they hid in the branches and wiped themselves. Every day, the top one flies around in the sky riding a bird, and the others board the ship in turn, ready to go. ...
The energy of the sun
Apart from atomic energy, volcanoes and earthquakes, solar energy is the total source of all energy on the earth. So, how much did the whole earth receive? The sun emits a lot of energy? Scientists imagine putting an instrument to measure the total solar radiation energy outside the earth's atmosphere. The total energy of solar radiation received per square centimeter per minute is 8.24 Joules. This value is called the solar constant. If the sun constant is multiplied by the spherical area with the radius of the average distance between the sun and the earth, the total energy emitted by the sun per minute is about 2.273×10.28 Joules per minute. The heat radiated by the sun into space every second is equivalent to the sum of the heat generated by the complete combustion of 1 100 million tons of coal, which is equivalent to the power of a 520 trillion horsepower engine. Every square meter of the sun's surface is equivalent to a power station with 85,000 horsepower. ) and the earth only receives 2.2 billion of these energies. The energy that the sun sends to the earth every year is equivalent to 654.38+000 billion kWh. Solar energy is inexhaustible and pollution-free, and it is the most ideal energy source.