The sudden appearance of a huge star and the astronomer who calmed the public opinion crisis

In December of the second year of the Jingde reign of the Northern Song Dynasty (January 1006 AD), the Northern Song Dynasty and the Liao Dynasty signed the famous Treaty of Chanyuan, which opened up a century of peaceful development. A few months later, the brightest star suddenly appeared in the night sky. Although it was located very south, people in many countries in the northern hemisphere still saw it. In China, this bright star confused and panicked the Northern Song Dynasty, which had just been freed from the war, but someone eventually eliminated this panic. Who was this person? How did he eliminate the panic? What was this bright star that suddenly appeared? Where did it come from and where did it go after it died?

Written by | Wang Shanqin

On the eighth day of the ninth month of the twenty-second year of the Tonghe reign of the Liao Dynasty (October 24, 1004 AD[1]), Empress Dowager Xiao Chuo and Emperor Shengzong of the Liao Dynasty, Yelü Longxu, personally led an army of 200,000 to attack the Northern Song Dynasty, on the pretext of recovering the ten counties south of the three passes of Waqiao, Yijin, and Yukou (located near the Baiyangdian Lake in Hebei Province). They were unstoppable and marched straight to the city of Chanzhou on the Yellow River (now Puyang, Henan Province). The nearby capital of the Northern Song Dynasty, Kaifeng, was greatly shaken.

That year was the first year of the Jingde reign of the Northern Song Dynasty. At the insistence of the famous prime minister Kou Zhun, Emperor Zhenzong of Song Zhao Heng[2], who had originally wanted to flee and move the capital, gritted his teeth and headed for the frontline city of Chanzhou. Not long after, the Liao general Xiao Tallin, who underestimated the enemy, was shot in the forehead by a crossbow arrow from the Song army on the city wall while scouting outside Chanzhou City, and was killed.

The morale of the Song army was greatly boosted, while the morale of the Liao army, which was already old and tired, was severely dampened. Empress Xiao decided to negotiate peace with the Northern Song Dynasty. In December of the second year of Jingde (January 1006 AD), the Northern Song Dynasty and Liao signed the famous Treaty of Chanyuan, which ended the intermittent war of 25 years at a relatively small material cost and brought about a hundred years of peace thereafter.

However, Empress Xiao's personal expedition still left a huge psychological shadow on Emperor Zhenzong of Song and some ministers in the court. In February of the third year of Jingde (March 1006 AD), Emperor Zhenzong of Song demoted Kou Zhun, who had forced him to take the risk of personal expedition, to Shanzhou.

A strange astronomical phenomenon that occurred shortly afterwards caused a sensation in the Northern Song Dynasty court and country, which further exposed the weak hearts of Emperor Zhenzong of Song and his ministers, so that they had to seek the explanation of an astronomer and astrologer to calm their inner fears.

A big star suddenly appeared

According to the Song Dynasty Huiyao Jigao, on the second day of the fourth month in the third year of the Jingde reign (Guiyou), which was May 1, 1006 AD, at nightfall, the observers at the Imperial Astronomical Observatory, who were in charge of astronomical observations, saw a large yellow star located to the east of Kulou and to the west of Qiguan in the Di constellation of the twenty-eight constellations. The star gradually became brighter over the next period of time.[3]

Dixiu covers parts of Libra, Serpens, Bootes, Virgo, Lupus, Hydra and Centaurus in the modern constellation system. It is divided into 11 "star officials", and "Riding Officer" is one of them, located in Lupus and Centaurus. Kulou is one of the 11 star officials of Spica, located in Centaurus.

Image: The white area in the middle is Lupus. Surrounding it are Scorpius, Libra, Centaur, and Hydra. 丨Image source: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)

The Qingli Guochao Huiyao also recorded this star, with basically the same details as above, but it recorded the time when this star appeared as the day of the 4th month of the lunar calendar.[4] Many people think that this day is the second day of the 4th month (May 1st in the Gregorian calendar). In fact, the 4th month of that year was the seventh day of the lunar calendar, which was May 6th in the Gregorian calendar. Even if we use the Gregorian calendar, which was not available at the time and was not promulgated until 1582, to calculate backwards, that day is May 12th.[5] No matter how we convert it, it cannot be May 1st. Therefore, the date given in the Qingli Guochao Huiyao is 5 days later than the date recorded in the Song Huiyao Jigao.

The History of Song, written during the Yuan Dynasty, also used the possibly incorrect date of April Wuyin, but gave a more detailed account of the star, saying that it was shaped like a "half moon" with "horns" and was dazzling, and could be used to distinguish objects at night. It also said that it disappeared due to the rotation of the celestial sphere - of course, it was actually due to the revolution of the earth - but reappeared in November of that year; after that, it disappeared in August and appeared in November[6] until it could no longer be seen.

According to current astronomical research, people know that the star that suddenly appeared is a "supernova". A supernova is a type of celestial explosion that can increase its brightness to about 10 billion times the brightness of the sun in a short period of time, but the brightest brightness of different supernovas is often different, and the difference can be very large. The dim ones are only tens of millions times brighter than the sun, and the brightest "superluminous supernovas" can reach hundreds of billions times the brightness of the sun.

Modern astronomers call the supernova seen in 1006 "Supernova 1006" (SN 1006).

Image: Modern astronomers simulated the sudden appearance of a supernova in 1006. The large white dot in the image is this star, and the upper left is Scorpio. Image source: Gilbert A. Esquerdo, Planetary Science Institute, Tucson, and SAO

Although this supernova alarmed the emperor, his ministers and common people of the Northern Song Dynasty, the people who saw it and recorded it were distributed in many countries.

The Japanese book “Era of Origin” (Chapter D) records the report of astronomy doctor Abe Yoshimasa (Abe no Yoshimasa, 955?-1019): On March 28, 1187 (April 28, Gregorian calendar), a “guest star” appeared in the “Qiguan”, and its color was white and blue.[7]

The word "guest star" comes from China. The ancient Chinese called those stars that suddenly appeared in the night sky and disappeared quickly "guest stars" because they were like guests. It can be seen that this record in Japan was 3 days earlier than that in China.

The Japanese book Mingyueki (Meigetsuki) Nomiyamoto23 also recorded this supernova: On April 2, the third year of Kankō (May 1, Gregorian calendar), after nightfall, a large guest star appeared in the “Cavalry Officer”, which looked like Mars, was very bright and shining. It could be seen in the south all night. Some people said that this might be the “Cavalry General Star” that had changed and started to brighten.[8]

The Persian (Iranian) astronomer Ibn Sina (ابن سینا, Ibn Sina, 980-1037) also observed the supernova in southern Uzbekistan.[9] According to his account, the star was motionless, had no tail, and became increasingly dimmer over a period of nearly three months until it disappeared; it was extremely bright, flickered constantly, and changed color over time.

The Egyptian astrologer and astronomer Ibn Ridwan (أبو الحسن علي بن رضوان المصري , Abu'l Hassan Ali ibn Ridwan Al-Misri, 988-1061) recorded the supernova as "a magnificent large round object, 2.5 to 3 times the size of Venus. Its light shines in the sky, more brilliant than the crescent moon." Ridwan noted that the star was low on the southern horizon.

Monks at the monastery of Saint Gall in Switzerland recorded: "It shrinks, expands, and disappears in a wonderful way... At the extreme edge of the southern sky, it appears unchanged for three months in a row, and its brightness exceeds that of all the constellations visible in the sky."

It is mentioned here that this supernova is located on the southern horizon. This is because the constellation Lupus is near 30 degrees south latitude, so it is very south.

In 2015, Iraqi and German scholars verified in a paper[10] that the Yemeni Arab scholar al-Yamani may have also recorded this supernova. Yamani's record is: On July 15, 396 AH (April 17 or 18, 1006 AD), one and a half hours after sunset, a star appeared in the east. It was four times the size of Venus (another version is: as big as Venus). It was not round, but more elliptical. The light it emitted was like fingers, showing turbulent characteristics, looking like disturbed water. The light it emitted was like sunlight. In the middle of September in the AH, its brightness began to decrease[10].

If Yamani's record is true, then the date recorded is about 10 days earlier than Japan's, making it the earliest observation of this supernova in the world. However, according to modern astronomical knowledge (see below), it is obviously unlikely that it will begin to dim after two months, and the reliability of the observer's visual observation of brightness and darkness will be affected by the atmosphere.

In addition to these written records, a rock painting on a stone in Arizona, North America may also depict this sudden supernova. This rock painting was drawn by the Hohokam indigenous people of North America at the time.

Image: Rock painting of the Hohokam Natives of North America. The solid star-shaped white dot in the middle right of the image may be the supernova that appeared in 1006 AD, and the scorpion-shaped celestial body on its left represents Scorpio. 丨Image source: John Barentine, Apache Point Observatory

https://www.space.com/2458-ancient-rock-art-depicts-exploding-star.html

A public opinion that caused panic in the Northern Song Dynasty

Zhou Keming (954/955-1017), the chief official of the Imperial Observatory, was not in Kaifeng when other officials observed the supernova on the second day of the fourth lunar month (May 1 in the Gregorian calendar). His colleagues in Kaifeng did not report the incident to the court for nearly a month. The court also remained officially silent.

Why was there such an embarrassing situation? Because many people at that time believed that this star was an ominous sign. The biography of Zhou Keming in the History of Song Dynasty records that after the star appeared, some people thought it was the "National Emperor" star, which indicated that war was about to break out.[11] According to the classification in ancient books, the characteristics of the National Emperor star are "large, yellow and white, with horns." The Yellow Emperor's Divination says that seeing the National Emperor star means that the country will be in turmoil, floods, famine and disease will occur, so the emperor hates it.[12]

Only a few months after the signing of the Treaty of Chanyuan, the Emperor Star suddenly appeared, foreshadowing a war. This caused Song Zhenzong, who believed in the connection between heaven and man, and his subjects to feel varying degrees of panic.

The main purpose of the ancient emperors to establish the Imperial Observatory was to formulate the calendar and predict good and bad luck based on astronomical phenomena. However, the officials in the Imperial Observatory who were still in the capital did not dare to explain the astronomical phenomenon "truthfully" and could only remain silent.

Image: Dengfeng Observatory in Henan Province, a world heritage site and a national first-class cultural relic protection site. It is the oldest existing observatory in China. It was first built in the Western Zhou Dynasty, and was greatly expanded by Yuan Dynasty astronomer Guo Shoujing and astronomer and mathematician Wang Xun in 1276. It was used for 364 years from 1281. Here, astronomers observe the shadow cast by the sun during the day and the stars at night. 丨Image source: tak.wing

Zhou Keming: Turning danger into fortune

After nearly a month of suffering, the officials of the Imperial Observatory in the capital finally waited for Zhou Keming to return to Kaifeng.

Zhou Keming's origins are not simple. According to the "History of the Song Dynasty", Zhou Keming's great-grandfather Zhou Defu was the Minister of Agriculture in the Tang Dynasty. His grandfather Zhou Jie was a Jinshi in the Kaicheng period. He was proficient in calendars and discovered errors in the "Dayan Calendar" and revised them. Later, due to the chaos of war, he took his family to Guangdong. After Liu Yan established the Southern Han regime in the south, he forced Zhou Jie to take up a position and be responsible for astrology and fortune-telling for the court. Zhou Jie's son and Zhou Keming's father Zhou Maoyuan inherited his father's career and served as the Junior Supervisor of the Sitian in the Southern Han. After the Southern Han surrendered to the Northern Song Dynasty, Zhou Maoyuan served as the Supervisor of the Northern Song Dynasty's Qintianjian[13].

Due to his family background, Zhou Keming was proficient in mathematics, calendar, astronomy, the five elements, and the prediction of good and bad luck. After examinations and interviews, he was awarded the title of Tong Jinshi and was appointed as the Director of the Imperial Observatory.

When the star was observed, Zhou Keming was either on official business in Guangdong or on his way back to Beijing from Guangdong. According to Zhou Keming’s later memorials, on his way back to Beijing, he had heard many people talking about the star and was aware of the uneasiness that permeated the government and the public.[14]

Relying on his profound knowledge of astrological literature, Zhou Keming quickly thought of explaining this star to the emperor and dispelling the panic-stricken public opinion.

On the first day of the fifth month (May 30, 1006 AD), Zhou Keming submitted a memorial on behalf of the Imperial Astronomical Observatory. In the memorial, he said: Based on the "Astronomical Records" and the "Jingzhou Divination", I have determined that this star is the "Zhou Bo" star. It is yellow and dazzling. The country that sees this star is a very prosperous country. It is a star that represents the morality of the country. [15]

Zhou Keming described the color of the supernova as yellow, not yellow-white, thus completing the transition from "King of the State" to "Zhou Bo". But this step was not enough, because according to the earlier astrology book "Huangdi Zhan", Zhou Bo star also indicated war, death, famine, and exile. Therefore, Zhou Keming did not quote "Huangdi Zhan", but quoted "Tianwenlu" and "Jingzhou Zhan", because the latter two books said that Zhou Bo star represented prosperity and auspiciousness.

Zhou Keming also suggested in his memorial that the emperor should let all civil and military officials celebrate the appearance of the star to calm the hearts of the people.[16] After hearing Zhou Keming's explanation, Emperor Zhenzong of Song was very happy, praised Zhou Keming, and approved his suggestion.[17] The confusion and panic that had been roiling the court for a month turned into a festive mood.

In this matter, Zhou Keming not only demonstrated his solid knowledge of astrology, but also his tactful ability to deal with public opinion. Through this series of operations and suggestions, he not only completely eliminated the negative public opinion caused by this star, but also made people believe that it was an auspicious sign.

In order to commend Zhou Keming's professional ability and his ability to interpret "turning misfortune into fortune", Emperor Zhenzong of Song gave him new official positions - "Prince Xima", who assisted the Crown Prince in government affairs and literature, and "Palace Secretary", which was equivalent to the Director of the Secretariat of the General Office of the Central Committee, and appointed him as an astronomer in the Institute of Astronomy in the Hanlin Academy.[18]

The Astronomical Institute of the Hanlin Academy and the Imperial Astronomical Observatory were independent organizations, and they verified each other's observation results. At that time, the Northern Song Dynasty built four observatories in the capital area. The most important ones were the "Yuetai" managed by the Imperial Astronomical Observatory and the "Houtai" in the Forbidden City managed by the Hanlin Astronomical Institute. The new position of astronomer of the Hanlin Academy Astronomical Institute made Zhou Keming the undisputed number one in the field of astronomy in the Northern Song Dynasty.

After Zhou Keming's explanation was officially adopted, this Zhou Boxing was also included in the list of auspicious "Jingxing", and was later described in the "Jingxing" of "History of Song Dynasty".

Some people think that this supernova is called "Zhou Boxing" because it was "certified" by Zhou Keming, and some people think that it is called "Jingxing" because it was discovered during the Jingde period. These are all wrong assumptions.

As early as the Tang Dynasty, the famous astrology book Kaiyuan Zhanjing cited the definition and description of Zhou Boxing in Huangdi Zhan. Besides, Zhou Keming would not have named this star after his surname in his memorial to the emperor, no matter how bold he was. As for Jingxing, this name already existed in the Bamboo Annals during the Spring and Autumn Period and the Warring States Period. Since then, Jingxing has been frequently used as an auspicious star in history books and astrology books.[19]

Color Mystery: Is Zhou Keming Lying?

The first step Zhou Keming took to resolve the public opinion crisis was to describe the color of supernova 1006 as yellow. However, other records give different colors. For example, the biography of Zhou Keming in the History of Song Dynasty said that people initially believed that it was a national emperor star, which shows that it should be yellow-white. The Japanese "Era Records" recorded its color as white-blue.

So, is Zhou Keming lying? We can say yes, or no. Because modern astronomical observations and theories tell us that after a supernova explodes, not only will the brightness change dramatically in a short period of time, but it will also expand dramatically. Therefore, the color of almost all supernovas will change significantly within a few dozen to more than a hundred days after their explosion, and supernova 1006 is no exception.

Soon after a supernova explodes, its surface temperature will exceed 10,000 degrees Celsius. As the supernova matter rapidly expands, the temperature of most supernovas will drop to 5,000 to 6,000 degrees Celsius within a few dozen days. As the temperature of supernovas drops from more than 10,000 degrees Celsius to 5,000 to 6,000 degrees Celsius, their color will evolve from blue-white (bluish-white) to yellow-white, and then to yellow. If the temperature continues to drop to 3,000 to 4,000 degrees Celsius, they will also turn orange-red.

Image: VLT's FORS image of a supernova SN 2005df that exploded "just above" NGC 1559. It is the same type of supernova as supernova 1006. Image source: ESO

https://www.eso.org/public/images/eso0527a/

With this modern knowledge, we can analyze the color evolution of this supernova. In addition to the records from Yemen, which have yet to be confirmed, the earliest record from Japan is that the temperature of supernova 1006 was still very high, so it may appear bluish white; three days later, when Chinese astronomical officials observed it, its color would not change significantly; but within a month, it would turn into yellowish white, and may even turn into yellow.

Zhou Keming submitted his memorial at least one month after the explosion of Supernova 1006, when it may have been yellowish. If Zhou Keming said it had always been yellow, then Zhou Keming was lying. However, if Zhou Keming said it was yellow "recently", then he was probably reporting truthfully, at most slightly exaggerating. Obviously, Zhou Keming acquiesced to the latter model, because in this model, the star is more easily interpreted as a lucky star.

In fact, the color of celestial bodies and all other luminous objects reflects the temperature of the celestial bodies. High-temperature celestial bodies tend to be bluish-white, low-temperature celestial bodies tend to be orange-red or even dark red, and celestial bodies with medium temperatures tend to be yellow.

It’s just that people can’t observe the color changes of most celestial bodies in their lifetime. Supernovas are different. Their brightness and radius change rapidly within a few dozen days after the explosion, causing their temperature to change significantly, and thus causing the color to change significantly.

Image: The Winter Triangle and Orion, taken by a ground-based telescope. The orange-red star is Betelgeuse, which has a temperature of about 3600 K, or about 3330 degrees Celsius, and is therefore orange-red. The huge blue-white star at the bottom is Sirius, which has a temperature of about 9940 K, or about 9670 degrees Celsius, and is therefore blue-white. 丨Image source: Akira Fujii

The "future" and "predecessor" of supernova 1006

In 1965, astronomers used radio telescopes to discover a shell-like object in the radio source near Beta Lupus, which was eventually confirmed to be the remnant of the explosion of supernova 1006. According to analysis and calculation, it is about 7,200 light years away from the Earth (1 light year is about 9.5 trillion kilometers). The figure below is a multi-band composite image of the remnant of supernova 1006 synthesized from data obtained by multiple telescopes. Continuous observations show that it is still expanding at a high speed.

Figure: A multi-band composite image of the remnant of the 1006 supernova taken by multiple telescopes. The diameter of the supernova remnant in the figure has reached about 60 light years. Among them, red represents radio images; yellow, orange and light blue represent optical images taken by different telescopes; cyan represents X-ray images. It represents visible light images taken by other optical telescopes. 丨Image source: NASA, ESA, and Z. Levay (STScI).

https://www.spacetelescope.org/images/opo0822b/

Astronomers have now determined that Supernova 1006 is a Type Ia supernova. Type Ia supernovae are produced in two ways: (1) in a binary system, a white dwarf devours the material of a companion star, reaching a mass of about 1.4 times that of the Sun, and then explodes; (2) in a binary system, two white dwarfs merge, resulting in an explosion.

If it is the former, the companion star will survive the explosion of the white dwarf. In 2012, astronomers tried to search for the companion star of this supernova, but did not find any.[20] This means that this supernova was most likely formed by the explosion of two white dwarfs merging.

Image: An artistic conception of two white dwarfs forming a binary white dwarf system. Source: ESO/L. Calçada

https://www.eso.org/public/images/eso1505a/

If these studies are reliable, we can describe this sequence of events as follows.

About tens to more than 10 billion years ago, two stars in the Milky Way that were larger than the sun formed a binary star system, revolving around a common center ("center of mass"). After hundreds of millions to billions of years, they expanded and ejected their outer layers, and the remaining inner cores evolved into white dwarfs, whose density is hundreds of thousands of times that of water or even higher. After that, the pair of white dwarfs continued to revolve around the center of mass and continued to approach each other due to the continuous loss of gravitational waves.

Image: The Dumbbell Nebula (M27) photographed by the Very Large Telescope (VLT) of the European Southern Observatory (ESO). It evolved from a medium-mass star. The outer gas ejected by this star formed this beautiful "planetary nebula", leaving behind a white dwarf with a mass of about 0.56 times that of the sun, but its radius is only 1/18 of that of the sun. Image source: ESO

After about hundreds of millions to billions of years, about 8,200 years ago, the pair of white dwarfs that kept approaching each other finally collided and exploded violently. About ten days later, its brightness increased sharply, reaching about 10 billion times the brightness of the sun at its brightest. Then, its brightness began to decrease. Ten days is the typical time for the brightness of a Type Ia supernova to rise, which is why it is said above that it is impossible for it to continue to brighten within two months.

The light it emitted traveled through the Milky Way at a speed of 300,000 kilometers per second for about 7,200 years. A small part of it finally arrived over the Earth in the spring of 1006 AD, was recorded, and was later named "Supernova 1006."

Despite its distance, Supernova 1006 became the brightest star in the night sky at the time, and was seen by astronomers from many countries, causing panic in the court and the people of the Northern Song Dynasty - the emperor was silent and the ministers wept (edited). Zhou Keming, the chief of the Imperial Astronomical Observatory of the Northern Song Dynasty, interpreted it as an auspicious star, defusing the public opinion crisis.

Of course, we are not telling this story to advocate learning Zhou Keming's smooth tactics, nor to support astrology. As mentioned in the text, different astrology books give completely opposite explanations for the golden Zhou Bo Star; as for the Guo Huang Star, they have not even determined its color uniquely: some astrology books say it is yellow-white, while others say it is red. It can be seen that astrology has no scientific basis.

We just use this story about people to tell the story of the stars.

Image: Ultraviolet, visible and near-infrared images of the core region of the globular cluster Omega Centauri taken by Hubble's Wide Field Camera 3 (WFC3). There are about 100,000 stars in this core region. Image source: NASA, ESA and the Hubble SM4 ERO Team

https://esahubble.org/images/heic0910g/

Notes

[1] The Gregorian calendar at that time was the Julian calendar. Unless otherwise specified, all references to the Julian calendar in this article are to the Julian calendar. The Julian calendar is different from the Gregorian calendar we use today. The average Julian year is 365.25 days, while the actual tropical year is 365.2422 days, which can lead to discrepancies over time. The Gregorian calendar was introduced in 1582 to correct the Julian calendar. If we use the Gregorian calendar to calculate backwards to 1006 AD, the date is 6 days longer than the Julian calendar. Now it is 13 days longer.

[2] Emperor Zhenzong himself was not a famous emperor, but four lines from one of his poems are extremely famous: “Books contain a thousand bushels of grain,” “Books contain a golden house,” “Books contain carriages and horses as numerous as a cluster,” and “Books contain a beautiful woman like jade.”

[3] Original text: "On May 1, the third year of the Jingde reign of Emperor Zhenzong of the Song Dynasty, the Imperial Astronomical Observatory reported: On the first watch of the second night of April, a large yellow star was seen, rising from the east of the storehouse and west of the riding official. It gradually became brighter and was measured at the third degree of the Shi." (According to Song Huiyao Jigao, Volume 52)

[4] Original text: “On the first day of the fifth month of the third year of the Jingde reign, the Astronomical Observatory’s Secretary reported: On the fourth month of the fourth month, a large yellow star was first seen, east of the storehouse and west of the cavalry official, and gradually became brighter.” (Qingli Guochao Huiyao)

[5] The conversion between the lunar calendar and the Gregorian calendar (including the Julian calendar and the Gregorian calendar) can be found at https://ctext.org/. The conversion of the fourth month of the lunar calendar in the third year of Jingde can be found at https://ctext.org/date.pl?if=gb&entityid=997417&year=3&month=4&day=15

[6] Original text: "On the 23rd day of the fourth month of the third year of the Jingde reign, Zhou Boxing appeared. It appeared one degree west of the southern Qiguan of Di. It was shaped like a half-moon with sharp horns. It was bright and could reflect things. It passed east of Kulou. In August, it followed the celestial wheel into the turbidity. In November, it appeared again in Di. Since then, it has been seen in the east in November and in the southwest in August." ("History of the Song Dynasty", Volume 56, "Records 9", "Jingxing")

[7] Original text: “On the 28th day of the third month of the third year of the Kankō era, a guest star entered the sky, its color was white and blue, and the astronomical doctor Abe Yoshimasa reported it.” Note that the 28th day of the third month of the third year of the Kankō era should be Gengwu, not Wuzi. The original text records this incorrectly.

[8] Original text: "On the second day of the fourth month of the third year of Kuanhong, at night, a large guest star appeared in the cavalry formation, like Mars, shining brightly. It was visible in the south all night. Some said that the star of the cavalry formation general had transformed into its original form and become brighter."

[9] Some reports and sources place the location as Iran. However, later research suggests that the location is in Uzbekistan.

[10] Rada, W. & Neuhäuser, R. Supernova SN 1006 in two historic Yemeni reports. Astronomische Nachrichten, 336, 3, 249 (https://ui.adsabs.harvard.edu/abs/2015AN....336..249R/abstract)

[11] Original text: “In the third year of Jingde, a large star appeared in the west of the Di people. No one could identify it. Some said it was an evil star of the emperor and a sign of war.” (History of the Song Dynasty, Volume 461, “Medical Techniques and Prescriptions”, “Zhou Keming”)

[12] Original text: “When a country is prone to change, if there is a flood or famine, the ruler will hate it and the people will suffer from many diseases.”

[13] Original text: "Zhou Keming, courtesy name Zhaowen, was the son of Defu, a minister of the Ministry of Agriculture in the Tang Dynasty. His grandfather Jie was a Jinshi in the Kaicheng period, and was awarded the title of Jiawei. He served as a proofreader in the Hongwen Academy. During the Zhonghe period, when Emperor Xizong was in Sichuan, Jie wrote a letter of more than 10,000 words on how to deal with the chaos. He was promoted to Deputy Director of the Ministry of Water Resources, and was later promoted to Junior Minister of the Ministry of Agriculture. Jie was proficient in calendar calculation. He once found that the numbers in the Dayan calendar were wrong, so he elaborated on the method and wrote the 24 chapters of the Extreme Derivatives to explore the numbers of heaven and earth. At that time, the world was in chaos, and Jie used astronomy to predict the situation. He thought that only Lingnan could be a safe place, so he sent his brother Ding to ask for help. He was a military officer in Fengzhou. When Jie passed the imperial examination, he also resigned from his post and took his family to the south to Lingbiao. Liu Yin had heard of his name and often asked him to predict astronomical disasters. Jie, who was old, had once been nominated for the imperial examination, and was ashamed to be presumptuous in astronomical affairs, so he excused himself from illness and did not go out. When Qian succeeded to the position, Jie was forced to take office and appointed as the Supervisor of the Astronomical Department, and asked about the shortness of the country's prosperity. ... Jie's son Maoyuan also inherited Qian's knowledge. He served Qian and became the Junior Supervisor of the Astronomical Department. He returned to Song and was appointed as the Supervisor and died there. He was Keming's father. "(Song History, Volume 461, "Fangji Shang", "Zhou Keming")

[14] Original text: “I have heard on the road that people both at home and abroad are quite confused about this matter.” (History of the Song Dynasty, Volume 461, “Medical Techniques and Treatments”, “Zhou Keming”)

[15] Original text: "According to the "Astronomical Records" and "Jingzhou Divination", the star is called 'Zhou Bo', its color is yellow, its light is brilliant, and the country where it is seen will prosper. This is a star of virtue." ("History of the Song Dynasty", Volume 461, "Medical Techniques", "Zhou Keming")

[16] Original text: “I wish to allow civil and military officials to celebrate and reassure the people of the world.” (History of the Song Dynasty, vol. 461, “Medical Techniques and Treatments”, “Zhou Keming”)

[17] Original text: “The emperor was pleased with his suggestion and immediately granted his request.” (History of the Song Dynasty, vol. 461, “Medical Techniques”, “Zhou Keming”)

[18] Original text: "He was appointed as the Prince's Groom and Palace Secretary, and was also in charge of the Imperial Academy of Astronomy, and also served as the Supervisor of the Imperial Academy." (History of the Song Dynasty, Volume 461, "Medical Techniques", "Zhou Keming")

[19] Sima Qian of the Han Dynasty wrote in the Records of the Grand Historian: Book of Celestial Officials: "Jingxing is the star of virtue. Its shape is unpredictable, and it often appears in countries with good moral principles." The Kaiyuan Divination Classic quoted Song Jun's statement: "Jingxing is large and hollow in the middle." Zheng Xuan of the Eastern Han Dynasty explained: "Jing means big and bright."

[20] González Hernández, JI, et al. No surviving evolved companions of the progenitor of SN 1006. 2012, Nature, Volume 489, Issue 7417, 533

Special Tips

1. Go to the "Featured Column" at the bottom of the menu of the "Fanpu" WeChat public account to read a series of popular science articles on different topics.

2. Fanpu provides a function to search articles by month. Follow the official account and reply with the four-digit year + month, such as "1903", to get the article index for March 2019, and so on.

Copyright statement: Personal forwarding is welcome. Any form of media or organization is not allowed to reprint or excerpt without authorization. For reprint authorization, please contact the backstage of the "Fanpu" WeChat public account.