Sunspots refer to the dark areas that sometimes appear on the surface of the sun's photosphere, where magnetic fields gather.Sunspots are the most prominent phenomenon that can be seen on the surface of the sun.A medium-sized sunspot is about the same size as the earth.Sunspots exist on the surface of the solar photosphere, where magnetic fields gather.Its number and location will change periodically at regular intervals.According to statistics, the weather or climate anomalies on the earth are closely related to sunspot activities.[6-7]
The formation and disappearance of sunspots can take days to weeks.When strong magnetic field emergessunlightOn the surface, the background temperature of this area slowly drops from 6000 degrees Celsius to 4000 degrees Celsius, when this area appears as a dark spot on the sun's surface.The darkest part in the center of the sunspot is called the umbra, which is the region with the strongest magnetic field.The area around the umbra that is not too dark and is striped is called penumbra.The sunspot rotates along with the sun's surface and completes its rotation in about 27 days.[1]
Long term observations have found that when there are many sunspots, other solar activities will be more frequent.Light spots always appear in the photosphere near the sunspot, and spectral spots always appear in the chromosphere above the sunspotProminence(dark stripe).At the same time, most of the solar eruptions also occur in the atmosphere above sunspots.Therefore, from the lower level to the upper level of the solar atmosphere, sunspots form an activity center——Solar active region。The sunspot is not only the core of the active area, but also the most obvious symbol of the active area.
Chinese name
Sunspot
Foreign name
Sunspot
Composition
Umbra
Discovery
The earliest record is that Chinese Han Dynasty people in 28 BC
Genesis
Under strong magnetic field, the temperature is lower than that around, and dark spots appear
Sunspots are dark spots that often appear on the solar photosphere.It is the basic symbol of solar activity.According to statistics, the weather or climate anomalies on the earth are closely related to sunspot activities.[9]
Discovery records
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There are abundant visual records of sunspots in China's history books, more than 100 times in the official history alone.It is now recognized that the first clear sunspot record in the world was observed by Chinese Han Dynasty people in 28 BC.It is recorded in the Book of the Han Dynasty: "At the end of the third month of the first year of Emperor Cheng Heping's reign, the sun rose yellow, black, as big as money, and lived in the center of Japan".
Moving sunspots recorded by Italian astronomer Galileo
In the West, the first record of a sunspot was in 807, but for a long time there was no correct concept of it. It was regarded as a planet passing in front of the sun until 1610,[8]Italian astronomerGalileoIt is the first time to see sunspots with a telescope, and sunspots are a very common phenomenon on the surface of the sun.However, this observation results contradict the religious doctrines at that time.Since 1818, there have been relatively regular daily sunspot observations, so there are relatively reliable sunspot data.The sunspot records from 1610 to 1818 are inconsistent and uneven, and there are various systematic errors, especially the observation records before 1750 have great uncertainty.
The routine observation of sunspots not only makes us realize the change law of sunspots themselves, but also reveals other phenomena and laws on the sun.Such as solar magnetic field, solar rotation, white lightsolar flareAre found in sunspot observation.
Sunspot origin
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Careful observation of sunspots shows that a mature sunspot is composed of dark parts in the center color and dark parts around it.The former is the umbra of sunspots, and the latter is the penumbra of sunspots.The sunspot is the low temperature area on the solar photosphere, the absolute temperature of the umbra area is about 4000 ℃, and the penumbra is 5400 ℃.Therefore, the sunspot is not black in fact. It is only because its temperature is lower than the photosphere that it appears black against the bright photosphere background.
Magnetic field structure of solar surface
The direct reason for the low temperature of the sunspot is that it has a strong magnetic field. The magnetic field intensity is between 1000 gauss and 4000 gauss, 10000 times higher than the magnetic field intensity on the earth.The strong magnetic field can inhibit the outward transmission of energy in the sun through convection.Therefore, when a strong magnetic field emerges on the surface of the sun, the background temperature of the region slowly drops from 5700 ℃ to about 4000 ℃, making the region appear as dark spots, that is, sunspots.
Sunspots tend to appear in groups.A typical mature sunspot group consists of two parts. Due to the rotation of the sun, the western part is always in front, called the leading part;Correspondingly, the eastern part is called the following part.The magnetic fields of the leading and following sunspots are opposite in polarity. One shows the north magnetic pole (N), and the other shows the south magnetic pole (S). Therefore, such sunspot groups are also called bipolar sunspot groups.There are also unipolar groups with only one polarity and multipolar groups with complex polarity distribution in sunspot groups.In general, the larger the sunspot group, the more complex the magnetic field polarity and the greater the magnetic field intensity.
Observational characteristics
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Growth and evolution of sunspot groups
Sunspots and the Earth
Many sunspot groups are often formed on the solar surface.There are one, two to dozens of sunspots in each sunspot group, and the diameter of each sunspot is about hundreds to tens of thousands of kilometers.The size of the sunspot group is expressed by its area on the solar surface, and the unit is one millionth of the area of the solar hemisphere.One hundred area units are equivalent to the area of the earth, the area of ordinary sunspot groups is hundreds of area units, and the area of large sunspot groups can reach thousands of area units.
The evolution process of sunspot groups usually changes from simple to complex, and then to simple.At first, it was a small black spot, and gradually developed into a bipolar sunspot group consisting of two large sunspots with opposite polarity.There are many small sunspots between the two big sunspots. While the big sunspots gradually increase, the distance is larger and larger, and then gradually split, and finally disappear.The short life span of sunspot groups is only 1~2 days, and the long life span can reach several months. Most sunspot groups can last for 1~20 days.
In 1843,GermanyAstronomerSchwabThrough our daily sunspot observations from 1826 to 1843, we found for the first time that the number of sunspots on the solar surface has a cyclical change of about 11 years.
In 1848, Swiss astronomerWolff For the first timeSunspot phase logarithm(or called Wolff number), which is defined as R=K (10g+f), where g and f respectively represent the sunspot group and the number of sunspots on the solar surface,The K value will vary depending on the observatory's observation telescope (aperture and focal length), observation method (such as visual inspection or photography), weather conditions at the observation site (atmospheric transparency and visual acuity) and the situation of the observer (technology, experience and stability).For fixed instruments and mature observations, the K value is close to a constant.After Wolff's collection and collation, the basically uninterrupted daily record of the relative number of sunspots can be pushed forward to 1818, the monthly average of the relative number of sunspots can be pushed forward to 1749, and the annual average value can be pushed forward to 1610.[2]
From long-termSunspot phase logarithmIt can be seen from the record that the average value of the relative number of sunspots obviously shows a periodicity of about 11 years, with the shortest being 9.0 years and the longest being 13.6 years.This periodic change of solar activity can be easily seen from the number of sunspots and the change of 10.7cm solar radio flux.The maximum and minimum years of the annual average value of the relative number of sunspots are called the maximum year (peak year) and minimum year (valley year) of solar activity, respectively.Usually, the solar maximum year with relatively high sunspot annual mean value and its adjacent years are also called the solar maximum year;The solar activity minimum years with relatively few sunspots and the adjacent years are called low solar activity years.
There is a solar cycle between two adjacent minimum years.It is stipulated that the activity week starting from the minimum year of 1755 is the first week.
Butterfly dance steps of sunspot
Influenced by Schwab's discovery, British astronomerCarringtonThrough daily sunspot observations from 1853 to 1861, it was found for the first time that the latitude position of sunspots on the solar surface moved to the equator with time;German astronomer Gustav Schborrell further analyzed the observational data of Carrington and found that the sunspot migration on the solar surface showed a butterfly pattern distribution.
Butterfly dance steps of sunspot
At the beginning of the solar activity cycle, the average latitude of sunspot groups in the northern and southern hemispheres is around 30 °. As time goes on, the latitude of sunspot emergence gradually shifts to the solar equator, which is about 15 ° near the maximum year. At the end of the activity cycle, the average latitude of sunspot groups is about 8 °;At the same time, at the end of each activity week, new sunspot groups begin to appear in the high latitudes, forming the situation that the previous week's sunspots exist in the low latitudes and the new week's sunspots exist in the high latitudes at the same time, which will last about a year.If we take the latitude of the sun as the ordinate and time as the abscissa, and draw sunspots on the picture, we will get a string of beautiful butterfly patterns dancing.
Bright wall structure of sunspot
Bright wall structure of sunspot
National Astronomical Observatory, Chinese Academy of SciencesTogether with the researchers of Yunnan Observatory, we made comprehensive use of the data of the New One meter Vacuum Solar Telescope (NVST) in Fuxian Lake, Yunnan, the American Solar Dynamics Observatory (SDO) and the Solar Interfacial Layer Imaging Spectrometer (IRIS), and found the vertical oscillation bright structure on the sunspot bright bridge for the first time, and named it "light wall".
In late October 2014, the largest sunspot group in 24 years appeared on the visible solar surface, with the active region number of 12192.The TiO 705.8 nm image of NVST shows that the negative main sunspot in the active region 12192 has complete umbra and penumbra structures, and there is a strong bright bridge structure in the umbra region of the sunspot.The IRIS 133 nm image shows that there is a vertically oscillating light structure above the light bridge structure, like a wall rooted in the light bridge, so it is named as the light wall.The whole bright wall is brighter than the surrounding area, especially the top of the wall, which is visible in multiple extreme ultraviolet bands of SDO.The average height of the bright wall is 3.6 trillion meters.The top of the bright wall moves up and down, forming a continuous oscillation. The average amplitude and average oscillation speed are 0.9 trillion meters and 15.4 kilometers/second, respectively.Through the wavelet analysis of the height change of the bright wall, it is found that the main oscillation period of the bright wall is 3.9 minutes.The researchers proposed that the solar radial pulsation caused by the pressure wave excited the oscillation of the bright wall, and the continuous brightness enhancement of the bright wall indicates that there is a continuous small-scale magnetic reconnection or magnetoacoustic heating process.
Before that, according to people's traditional understanding, the basic structure of mature big sunspots was roughly composed of umbra, penumbra and bright bridge.The latest observation data show that the bright wall is a basic structure inside sunspots.The discovery of the bright wall structure makes people have a new understanding of the structure of sunspots.[3]
Introduction to sunspots
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The sun is the source of light and heat on the earth, and its every move will have a variety of impacts on the earth.
It is observed that the sun's father-in-law sometimes grows "small black moles" one by one on his face. Why?How will it affect the earth?
Sunspot
The "little black spot" on the face of Father Sun is actually called sunspot.
Sunspot is a kind of solar activity occurring on the photosphere of the sun, which is the most basic and obvious in the solar activity.It is generally believed that a sunspot is actually a huge vortex of hot gas on the surface of the sun, with a temperature of about 3000-4500 ℃.Because its temperature is 1000 to 2000 degrees Celsius lower than the surface temperature of the sun's photosphere, it looks like some dark spots.A fully developed sunspot consists of a darker core and the surrounding lighter parts, with a depression of about 500 kilometers in the middle.A small sunspot is about 1000 kilometers, while a large sunspot can reach 200000 kilometers.The formation of sunspots is closely related to the solar magnetic field.But astronomers have not yet found the exact answer to the question of how it came into being.However, scientists speculate that it is very likely that the strong magnetic field has changed the material structure of a certain area, so that the light and heat inside the sun can not reach the surface effectively, forming such a "low-temperature zone".That is, the "small black spots" on the sun.
Sunspots seldom move alone and usually appear in groups.The activity cycle of sunspots is 11 years, which will have an impact on the earth's magnetic field when active. When a large group of sunspots appear on the sun, there will be a magnetic storm, which will make the compass shake disorderly and cannot correctly indicate the direction;Pigeons who are good at identifying directions usually get lost;Radio communication will also be seriously hindered, or even suddenly interrupted for a period of time. These abnormal phenomena will pose a serious threat to the safe navigation of aircraft, ships and satellites, as well as television and fax.
It seems that these "small black spots" not only affect the beauty of the sun, but also have a certain impact on human production and life!
This is the cause and influence of sunspots.[4]
Research progress
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October 21, 2012, JapanNagoya University The research team announced that by analyzing the solar observation data, it was found that during the period when the number of sunspots in the northern hemisphere of the sun increased most significantly, the north and south poles of the magnetic field would reverse.The same thing happens in the south pole of the southern hemisphere of the sun.This reversal of the sun's magnetic poles is similar to the related solar changes during several Earth cooling periods in history, but whether this indicates that the Earth will become cold in the near future remains to be observed and studied.[5]
