Who has information about the sun?
The sun is a hot gas planet that emits its own light and heat. Its surface temperature is about 6,000 degrees Celsius, and its core temperature is as high as 15 million degrees Celsius. The radius of the sun is about 696,000 kilometers, which is about 109 times the radius of the earth. Its mass is 1.989×1027 tons, which is about 332,000 times that of the Earth. The average density of the sun is 1.4 grams per cubic centimeter, which is about 1/4 of the density of the earth. The average distance between the sun and our earth is about 150 million kilometers.
The Sun is an ordinary star in the Milky Way. It is located on the Orion spiral arm north of the Milky Way, about 2.3 light-years away from the center of the Galaxy. It rotates around the center of the Galaxy at a speed of 250 kilometers per second. It takes about 250 million years to complete one revolution. The sun also rotates, and its period is about 25 days in the equatorial zone of the sun and about 35 days in the polar regions.
Through the analysis of the solar spectrum, it is known that the chemical composition of the sun is almost the same as that of the earth, but the proportions are different. The most abundant element on the sun is hydrogen, followed by helium, carbon, nitrogen, oxygen and various metals.
The structure of the sun
The structure of the sun is mainly divided from the inside out: the center is the thermonuclear reaction zone, outside the core is the radiative layer, outside the radiative layer is the troposphere, and outside the troposphere It's the solar atmosphere.
It can be deduced from the theory of nuclear physics that the center of the sun is the thermonuclear reaction zone. The central region of the sun occupies 1/4 of the entire solar radius and is approximately more than half of the entire solar mass. This indicates that the density of matter in the central region of the sun is very high. Up to 160 grams per cubic centimeter. Under the attraction of its own strong gravity, the central region of the sun is in a state of high density, high temperature and high pressure. It is the birthplace of the huge energy of the sun.
The energy generated in the central region of the sun is transferred mainly in the form of radiation. Outside the central area of the sun is the radiative layer. The range of the radiative layer is from 0.25 solar radii at the top of the thermonuclear central area to 0.86 solar radii. The temperature, density and pressure here all decrease from the inside to the outside. In terms of volume, the radiative layer accounts for most of the entire solar volume.
In addition to radiation, the energy inside the sun spreads outwards through convection processes. That is, from 0.86 solar radii of the sun outward to the bottom of the solar atmosphere, this interval is called the troposphere. The properties of the gas in this layer change greatly and are very unstable, forming obvious up-and-down convection motion. This is the outermost layer of the Sun's internal structure. Outside the solar troposphere is the solar atmosphere. The solar atmosphere can be divided into photosphere, chromosphere and corona from the inside out. The dazzling sun we see is the intense visible light emitted by the photosphere in the sun's atmosphere. The photosphere is located outside the troposphere and is the lowest or innermost layer of the solar atmosphere. The thickness of the photosphere is about 500 kilometers. Compared with the solar radius of about 700,000 kilometers, it is like the ratio of human skin to muscles. When we say that the average temperature of the sun is about 6000 degrees Celsius, we are referring to this layer. Beyond the light sphere is the color sphere. Normally, because the Earth's atmosphere scatters the intense light balls, the color balls are submerged in the blue sky. Only during a total solar eclipse can you have the opportunity to directly appreciate the red beauty of the chromatic sphere. The solar chromosphere is a magnetic field-filled plasma layer about 2,500 kilometers thick. Its temperature increases from the inside out, from about 4,500 degrees Celsius in the part connected to the photosphere to tens of thousands of degrees Celsius in the outer layer. Density decreases as height increases. The structure of the entire chromosphere is uneven. Due to the instability of the magnetic field, bursts of activity in the upper atmosphere of the sun often occur, resulting in flares.
The corona is the outermost layer of the sun's atmosphere. The material in the corona is also plasma, its density is lower than that of the chromosphere, and its temperature is inversely higher than that of the chromosphere, reaching millions of degrees Celsius. During a total solar eclipse, the very bright silvery white light seen around the sun is the corona.
The energy of the sun
Except for atomic energy, volcanoes and earthquakes, solar energy is the total source of all energy on the earth. So, how much does the entire earth receive? The sun emits a lot of energy? Scientists imagine placing an instrument outside the Earth's atmosphere to measure the total solar radiation energy. The total solar radiation energy received per square centimeter is 8.24 joules per minute. This value is called the solar constant. If the solar constant is multiplied by the area of a sphere whose radius is the average distance between the sun and the earth, we get the total energy emitted by the sun per minute, which is approximately 2.273 × 1028 joules per minute. The Earth only receives one 2.2 billionth of this energy. The energy that the sun sends to the earth every year is equivalent to 10 billion kilowatt-hours of electricity. Solar energy is inexhaustible, non-polluting, and is the most ideal energy source.
Sunspots
When observing the sun through a general optical telescope, what is observed is the activity of the photosphere (the innermost layer of the solar atmosphere). Many black spots, called sunspots, can often be seen on the photosphere. The size, number, location and shape of sunspots on the sun's surface vary from day to day. Sunspots are local areas of strong magnetic field formed by the violent movement of matter in the photosphere, and are important signs of photospheric activity. Long-term observation of sunspots will reveal that some years there are more sunspots, and some years there are fewer sunspots. Sometimes there are no sunspots on the sun for several days or dozens of days. Astronomers have long noticed that there is a gap of about 11 years from the year with the most (or least) sunspots to the next year with the most (or least) sunspots. In other words, sunspots have an average activity cycle of 11, which is also the activity cycle of the entire sun.
Astronomers call the years when the sun is darkest the most "solar activity peak years" and the years when the sunspots are the least "solar activity quiet years."
Solar Flare
Solar flare is one of the most violent solar activities. It is generally believed to occur in the chromosphere, so it is also called a "chromospheric explosion." Its main observational feature is that a rapidly developing bright spot suddenly appears on the solar surface (often above the sunspot group). Its lifespan is only between a few minutes and tens of minutes, and its brightness rises rapidly and declines slowly. Especially during peak solar activity years, flares occur frequently and become stronger.
Don’t look at it as just a bright spot. Once it appears, it will be an earth-shattering explosion. The energy released by this brightening is equivalent to the total energy of 100,000 to 1 million strong volcanic eruptions, or the explosion of tens of billions of 100-ton hydrogen bombs; and a larger flare erupts within one to twenty minutes. It can release a huge energy of 10 to 25 joules.
In addition to the sudden local brightening of the sun, flares are mainly manifested in the sudden increase in radiation flux from the radio band to X-rays; the flares emit There are many types of radiation. In addition to visible light, there are ultraviolet, X-rays and gamma rays, infrared and radio radiation, shock waves and high-energy particle flows, and even extremely high-energy cosmic rays.
Flares have a great impact on the earth’s space environment. There was an explosion in the sun's chromosphere, and there was an immediate lingering sound in the earth's atmosphere. When a flare erupts, a large number of high-energy particles are emitted and reach near the Earth's orbit, which will seriously endanger the safety of astronauts and instruments in the spacecraft. When the flare radiation comes near the earth, it violently collides with atmospheric molecules, destroying the ionosphere and causing it to lose its ability to reflect radio waves. Radio communications, especially shortwave communications, as well as television and radio broadcasts, will be interfered with or even interrupted. The stream of high-energy charged particles emitted by the flare interacts with the Earth's upper atmosphere to produce auroras and interfere with the Earth's magnetic field, causing magnetic storms.
In addition, flares also have varying degrees of direct or indirect impact on meteorology and hydrology. Because of this, people are increasingly concerned about the detection and prediction of flare outbreaks, and efforts are being made to uncover the mysteries of the flare maze.
Legend has it that during the Second World War, one day, the German frontline was in a tense situation, and Brooke, the operator of the German headquarters in the rear, was busy operating the radio station to convey orders. Suddenly, the sound in the headphones disappeared. He checked the machine and found that the radio was intact; he turned the knobs and changed the frequency, but to no avail. As a result, the front line pushed for contact and fell into chaos like a leaderless group, and the campaign ended in failure. Brooke was sentenced to death by a military court. He looked up to the sky and shouted, "You're wronged! You're wronged!" It was later found out that the "culprit" for this radio outage was a flare. Brooke's death was truly unjust. His death was because people didn't understand flares at the time.
Spectral spot (spectral spot)
A patchy tissue on the solar photosphere that is brighter than its surroundings. When observing it with an astronomical telescope, you can often find that some parts of the photosphere's surface are bright and some are dark. This kind of light and dark spots are formed due to the different temperatures here. The darker spots are called "sunspots" and the brighter spots are called "light spots". Spots often "perform" at the edges of the sun's surface, but rarely appear in the center of the sun's surface. Because the radiation in the central area of the sun's surface belongs to the deeper gas layer of the photosphere, and the light at the edge mainly comes from the higher parts of the photosphere, therefore, the light spot is higher than the surface of the sun and can be regarded as a "plateau" on the photosphere. ".
The light spot is also a strong storm on the sun, which astronomers jokingly call a "plateau storm." However, compared with the ground storm where dark clouds roll, heavy rain pours, and strong winds blow the grass and grass, the "plateau storm" is much milder in character. The brightness of the light spot is only slightly stronger than the quiet photosphere, generally only 10% larger; the temperature is 300°C higher than the quiet photosphere. Many light spots are closely related to sunspots and often "perform" around sunspots. A small number of spots have nothing to do with sunspots. They are active in the high latitude area of 70° and have a relatively small area. The average lifespan of the spots is about 15 days, and the lifespan of larger spots can be up to three months.
Light spots not only appear on the photosphere, but also on the chromosphere. When it "performs" on the chromosphere, the location of the activity roughly coincides with when it appears on the photosphere. However, what appears on the chromosphere is not called a "light spot" but a "spectral spot". In fact, the light spot and the spectrum spot are the same whole, just because their "residences" are at different heights. It is like a building, the light spot lives downstairs, and the spectrum spot lives upstairs.
Granular tissue
Granular tissue is a solar surface structure on the solar photosphere. It is in the shape of small polygonal particles and can only be observed with an astronomical telescope. The temperature of the rice grain structure is about 300°C higher than the temperature of the area between the rice grains, so it appears brighter and easier to see. Although they are small particles, their actual diameter is 1,000 kilometers to 2,000 kilometers.
The bright rice grains are likely to be hot air masses rising from the troposphere to the photosphere. They do not change with time, are evenly distributed, and show intense undulating motion.
When the rice grain tissue rises to a certain height, it will quickly cool down and immediately fall along the gaps between the rising hot air flows; its life span is also very short, coming and going in a hurry, from creation to disappearance, it is almost longer than that in the earth's atmosphere. Clouds dissipate even faster, with an average lifespan of only a few minutes. In addition, the super-granular structures discovered in recent years have a scale of about 30,000 kilometers and a lifespan of about 20 hours.
What’s interesting is that while the old rice grain tissue disappears, new rice grain tissue quickly appears in its original position. This continuous phenomenon is like what we see every day on boiling rice porridge. Hot bubbles that are constantly bubbling up and down.
Solar activity - prominence
Solar prominence is a solar activity phenomenon that protrudes outside the edge of the sun. When a solar prominence appears, the chromatic sphere in the atmosphere resembles a burning grassland, and the rose-red tongue-shaped gas rises like a fire. It has various shapes, some are like floating clouds, some are like arch bridges, some are like fountains, and some are like clumps of grass. , some are as beautiful as holiday fireworks, and overall their shape is just like earrings attached to the edge of the sun, hence the name "solar prominences".
The rising height of a solar prominence is about tens of thousands of kilometers. Large prominences can be hundreds of thousands of kilometers above the sun. They are generally about 200,000 kilometers long, and some can reach 1.5 million kilometers. The brightness of the solar prominence is much dimmer than the solar photosphere, so it cannot be observed with the naked eye at ordinary times. It can only be seen directly during a total solar eclipse.
Solar prominence is a very peculiar solar activity phenomenon. Its temperature is between 5000 and 8000K. Most of the solar prominence materials slowly fall to the sun's surface after rising to a certain height, but some solar prominence materials also float. In the lower layers of the corona, where the temperature is as high as 2 million K, it does not attach or disintegrate. It is as strange as there is a piece of ice that does not melt in a blazing steel-making furnace. Moreover, the density of the prominence material is 1000 times higher than that of the corona. ~10,000 times, it is really puzzling that the two can survive for several months.
Surfing
Surfing is also called "sun wave". An ejection phenomenon of material in the solar photosphere. It usually occurs over sunspots and has a strong ability to reappear. When a surf falls along the rising path, it will trigger a new surf to rise into the sky. This repeats, but its scale and height are smaller each time. , until it disappears.
The surf at the edge of the sun appears as a small, bright hummock with a sharp spike-shaped top that grows outward. The height of ascent varies from person to person. A small wave can only reach a few hundred kilometers, a large wave can reach 5,000 kilometers, and the largest one can reach 10,000 to 20,000 kilometers. The maximum ejection speed can reach 100-200 kilometers per second, which is more than 100 times faster than the fastest reconnaissance aircraft. When they reach their highest point, they begin to fall under the influence of the sun's gravity until they return to the sun's surface. People have found from high-resolution observational data that surfing is composed of a very small bundle of fibers, with a small distance between each fiber, which shines and moves together as a whole.
Needles
What is more common on the chromosphere are numerous needle-shaped small prominences of high-temperature plasma called "needles". Observe the edge of the sun's disk. Many small and bright "tongues of fire" can be seen, like clusters of burning grass on the sun. The width of the needle is about 800 kilometers, the height is 4400 to 9800 kilometers, and the average life span is about 5 minutes.
In the middle of the chromosphere, the number of needles is about 250,000; at 3,000 kilometers from the sun, the number is reduced to 93,000; at 15,000 kilometers from the sun, only about 200 are left indivual. Needles are ejected from the chromosphere at a speed of about 25 kilometers per second. Some rise at a constant speed, and some rise by jumping. When they rise to a certain height, they begin to fall under the influence of the sun's gravity.
In the mid-1970s, the "Skylab" launched by the United States discovered the phenomenon of super needles, with a width of 18,000 kilometers and a height of 43,000 kilometers, which are more than 10 times larger than ordinary needles.
Super needles can rise to an altitude of 35,000 kilometers, wander into the corona for a while, and then fall back to the chromosphere, where they can exist for up to 40 minutes