Chapter 16 Section 2 sunspots

Another aspect of the study of the sun is the observation of changes in the sun itself.Ancient Chinese astronomers observed the changes of the sun very carefully. They observed sunspots, prominences (er ears), and corona on the surface of the sun before BC.Among them, the records of Heizi are the most valuable. According to modern research, prominence is a flame rising from the sun's chromosphere, which is a kind of gas.The ancients saw this phenomenon and named it prominence, which means the earrings of the sun, that is, the extra things like human earrings on the side of the sun's disc.The earliest records of solar prominences in China also appeared in oracle bone inscriptions, which are called "three eclipses".Three scorpions are the meaning of three fire scorpions.

Sunspots are black spots that appear on the surface of the sun, and it is a kind of storm that appears on the surface of the sun.Because the storm is cooler than its nearby sun, the light appears dimmer.The earliest record of sunspots recognized in the world today is the first year of Heping, Emperor Cheng of the Western Han Dynasty in China (28 BC). "Hanshu Wuxingzhi" said: "In the first year of Heping, Chengdi, in March Yiwei, the sun rose yellow and there was black air. , as big as money, and lives in the center of Japan.” About the name Heizi, it first appeared in a record in the early years of the Western Jin Dynasty (268 A.D.).

The ancients recorded sunspots in detail, including the date, location and shape of appearance.Since sunspots are formed by storms on the sun, they generally appear for a relatively short time.Most of the sunspots seen by the naked eye are relatively large sunspots. According to ancient records, it often takes several days or even 10 days for them to disappear.The ancients observed the shape of sunspots very carefully, and described them as peaches, plums, money, melons, eggs, jujubes, people, and flying swallows.Sunspots often appear in groups.According to modern research, the sun itself is also constantly rotating from west to east. Astronomers call the sunspots that first appear on the west side of the solar disk as leading sunspots, and those on the east side of the sun are called trailing sunspots.Leading sunspots are often round and darker.Then the sunspots are larger and lighter in color, not necessarily round.Modern astronomers often divide sunspots into three categories: circular, elliptical and irregular.The ancients compared peaches, plums, money, etc. to round shapes, melons, eggs, dates, etc. to oval shapes, and people, birds, etc. to irregular shapes.Sunspots often appear in pairs from north to south, which are called bipolar sunspots, and oval sunspots may be bipolar sunspots.Irregular sunspots are often sunspot groups.

According to statistical research, the average occurrence cycle of sunspots is 11.33 years, which is consistent with the ancient records.The records of sunspots in ancient my country are a very precious astronomical heritage, which has important reference value for the study of solar physics, the relationship between the sun and the earth, climate change and weather forecast.