I became aware of the Cosmos Magazine article The unforgotten sisters: Sonduk, the astronomer queen by Gabriella Bernardi (hereinafter “Cosmos Magazine article,” archived version https://archive.is/j7d1n ) from somewhat implausible claims about the ancient Korean monarch Seondeok (善德王, styled 聖祖皇姑) being discussed as fact on social media. These include the claims that the female king was an astronomer herself as a princess, had a Tang ambassador named Lin Fang as a tutor, and predicted a solar eclipse as a teenager.

I found out from reading the article that it was adapted from an earlier book by the same author, Gabriella Bernardi's The Unforgotten Sisters: Astronomers and Scientists before Caroline Herschel (2016 Springer Praxis, hereinafter “Unforgotten Sisters”) and read the relevant chapter on Seondeok in the book. The chapter made similar implausible claims that I had not seen in any historical record or non-fictional discussions of historical records.

To prevent the further spread of possible misinformation and to correct the record if necessary, I set out to discover the source of these assertions about Seondeok starting with the bibliography of Unforgotten Sisters. Suspicions about these claims and subsequent research were recorded contemporaneously on a Mastodon thread. This page and linked pages are a more formal documentation and expansion of the findings.

• Yung-Chung Kim, Women of Korea: A History from Ancient Times to 1945 (2nd ed. 1977)

This book (hereinafter “Women of Korea”) was cited in the bibliography of Unforgotten Sisters and I read the parts relevant to Seondeok as a possible source for the unusual claims made by Bernardi. However, Women of Korea does not go beyond the known historical information on Seondeok and I could not find any mention of details unique to Unforgotten Sisters such as her passion for astronomy or having a Tang ambassador as a tutor. See Passages on Seondeok from Women of Korea (1977) for the transcribed contents of these pages.

• Sheri Holman, Sŏndŏk: Princess of the Moon and Stars (2002)

Not directly cited in Unforgotten Sisters and found by independent search, this middle-grade novel (hereinafter “Princess of the Moon and Stars”) has many striking similarities with the assertions about Seondeok that I could not trace to any historical source. There are even passages with very similar wording. See Comparison with Princess of the Moon and Stars.

I have looked through four other sources in the Unforgotten Sisters bibliography that might be relevant to Seondeok and that I had library access to, mostly biographical dictionaries of astronomers and scientists. I could not find any mention of her, however.

The fictional details about Seondeok claimed as fact are the most egregious errors, but there are issues with the discussions on Cheomseongdae as well. There is an ongoing dispute in the Korean historical and archaeology communities over whether the building was an observatory at all, but I do not expect most non-specialists in this specific field of Korean archaeology to be familiar with such specific disagreements.

More problematic are Bernardi's claims on the story behind the construction of Cheomseongdae and the method of observation from the tower, with the first evidently being another uncited invention of Holman's and the second not having any known basis in the historical record.

In the Cosmos Magazine article Bernardi claims the following about the background for the construction of Cheomseongdae:

Sonduk had begged her father for several years to set out on its building, but eventually accomplished the challenge on her own.

As far as I know, however, no historical record on Cheomseongdae goes into this level of detail about the background of its construction. The first record on Cheomseongdae is the following line in the Samguk Yusa (三國遺事):

別記云是王代鍊石築瞻星臺 (A separate record states that it was in the King's [Seondeok's] time that stone was shaped to build Cheomseongdae.)

- 三國遺事 記異卷第一 善德王知幾三事 (Stories from the Three Kingdoms, Extraordinary Events Book 1, Three Episodes of King Seondeok's Foreknowledge) Hangul translation / Scan of original record

Yet again, the only “basis” for the assertion that this was something Seondeok begged of her father seems to be Holman's Princess of the Moon and Stars in passages like the following:

It is my greatest desire to one day build an observatory here dedicated only to mapping the sky. I have hinted to Father that is what I want for my New Year's gift. (p. 9)

My heart leaped at his words, Grandmother. Finally, he would grant my desire.
"It is not an observatory," he said, as I unwrapped a small red package. Inside was a lovely golden bracelet ... I smiled weakly, trying to hide my disappointment ... (p. 43)

Bernardi states the following in the Cosmos Magazine article:

According to the historical accounts, when astronomers were observing in Sonduk’s tower, they laid on their back and watched the celestial objects through four domes on the top, arranged in a square and oriented towards the four cardinal points.

This would be remarkable if true because there is no such historical account to my knowledge, and to the knowledge of many scholars over the centuries who have speculated on how the Cheomseongdae was used for observation of the heavens—if it was at all, which some are skeptical about as mentioned above.

Ironically, this is one assertion that cannot be traced to Holman's Princess of the Moon and Stars because Holman states in the epilogue:

It is almost certain that a wooden platform made the tower even higher, but modern scientists are not absolutely sure as to how the tower was used. It is shrouded in mystery. (p. 161)

I am unsure about the strength of the wooden platform hypothesis, but at any rate this directly contradicts Bernardi's account. Furthermore, the acknowledgement of uncertainty over the specific mode of Cheomseongdae's usage is a much better-supported statement than a claim of historical records documenting a specific method, because no such record exists to the best of my knowledge.

If Bernardi can present such a historical record, of course, it would be a remarkable find. However, I personally could find no such record myself and could not trace it to any of her cited sources I could access.

• The claims about Seondeok not found in the recorded history appear to be drawn uncited and uncredited from the novel Princess of the Moon and Stars.
• The chapter in Unforgotten Sisters and the Cosmos Magazine article should be retracted or corrected to remove the fictional material.
• If the chapter and article are left as they are, they should be marked or otherwise notified as largely fictional, and Ms. Holman's permission should be sought for the use of details she originated, with appropriate credit. She may also be due some form of apology, acknowledgement, and recompense.
• There are other assertions with dubious support, such as the purported method of using the Cheomseongdae for observation, that need better sourcing.