Sunspots are composed of umbra and penumbra, and umbra is a particularly dark part. Penumbra is not too dark, but it is composed of many fiber textures and has a spiral structure. When the large sunspot group appears vortex structure, it indicates that the sun will change dramatically. People have discovered sunspot activity for thousands of years.

The average period of sunspot activity is 1 1 year. In the first four years or so, sunspots were constantly produced and increased, and their activities intensified. The year when the number of sunspots reaches the maximum is called the peak of solar activity. In the next seven years, sunspot activity gradually weakened and the number of sunspots became less and less. A year with very few sunspots is called solar activity valley year. According to international regulations, the sunspot cycle starts from 1755 and is the first week, and then it is arranged in turn. 1999 is the 23rd week.

Solar flare: 1 September, 8591day, two British astronomers observed the sun with a high-powered telescope. At the same time, near a large group of sunspots with complex shapes, they saw a large bright flash with dazzling light. This piece of light passed over the sunspot group, and its brightness gradually weakened until it disappeared. This is the most intense activity phenomenon on solar flares. Because this kind of flare is particularly powerful, it can also be seen under white light, so it is also called "white light flare". White light flare is extremely rare, and it is only possible to appear at the peak of solar activity. Flares generally only exist for a few minutes, and individual flares can last for several hours. Flares release a lot of energy when they appear. The total energy released by a large flare is as high as 1026 Joule, which is equivalent to the total energy of 1000 trillion megaton hydrogen bomb. Flares first broke out in the lower corona and then descended to chromosphere. What was observed with chromosphere telescope was the subsequent flare, or secondary flare.

Flares are divided into four grades according to the area, which gradually increase from 1 to 4, and those less than 1 are called sub-flares. The remarkable feature of flare is that there are many kinds of radiation, not only visible light, but also radio waves, ultraviolet rays, infrared rays, X rays, gamma rays and so on. A large number of ultraviolet rays and X-rays radiated by flares will seriously interfere with the absorption and reflection of radio waves by the ionosphere, so that short-wave radio waves are partially or completely absorbed, and the short-wave is weak or even completely interrupted.

The surface of the sun that people usually see is called the photosphere, which is the bottom layer of the solar atmosphere. Some rotating airflow, like a shallow dish, sinks into the middle for hundreds of kilometers. These rotating air currents are very similar to holes of different sizes and irregular shapes. They're dark. This is what astronomers call sunspots. The sunspot itself is not black, and the temperature is generally four or five thousand degrees Celsius. However, compared with the photosphere, its temperature is one or two thousand degrees lower. Against the brighter photosphere, it becomes a sunspot that looks like a dark sunspot without any light. Assuming that the photosphere 100% is covered by sunspots, the sun will still be quite bright, just a little darker than it is now. Sunspots are composed of umbra and penumbra, and umbra is a particularly dark part. Penumbra is not too dark, but it is composed of many fiber textures and has a spiral structure. When the large sunspot group appears vortex structure, it indicates that the sun will change dramatically. People have discovered sunspot activity for thousands of years. The average period of sunspot activity is 1 1 year. In the first four years or so, sunspots were constantly produced and increased, and their activities intensified. The year when the number of sunspots reaches the maximum is called the peak of solar activity. In the next seven years, sunspot activity gradually weakened and the number of sunspots became less and less. A year with very few sunspots is called solar activity valley year. According to international regulations, the sunspot cycle starts from 1755 and is the first week, and then it is arranged in turn. 1999 is the 23rd week. Solar flare 1 September, 8591day, two British astronomers observed the sun with a high-powered telescope. At the same time, near a large group of sunspots with complex shapes, they saw a large bright flash with dazzling light. This piece of light passed over the sunspot group, and its brightness gradually weakened until it disappeared. This is the most intense activity phenomenon on solar flares. Because this kind of flare is particularly powerful, it can also be seen under white light, so it is also called white light flare. "White flare is extremely rare, and it is only possible at the peak of solar activity. Flares generally only exist for a few minutes, and individual flares can last for several hours. Flares release a lot of energy when they appear. The total energy released by a large flare is as high as 1026 Joule, which is equivalent to the total energy of 1000 trillion megaton hydrogen bomb. Flares first broke out in the lower corona and then descended to chromosphere. What was observed with chromosphere telescope was the subsequent flare, or secondary flare. Flares are divided into four grades according to the area, which gradually increase from 1 to 4, and those less than 1 are called sub-flares. The remarkable feature of flare is that there are many kinds of radiation, not only visible light, but also radio waves, ultraviolet rays, infrared rays, X rays, gamma rays and so on. A large number of ultraviolet rays and X-rays radiated by flares will seriously interfere with the absorption and reflection of radio waves by the ionosphere, so that short-wave radio waves are partially or completely absorbed, and the short-wave is weak or even completely interrupted.