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.

The following are the claims in the Cosmos Magazine article and/or the Seondeok chapter of Unforgotten Sisters that I found dubious for not being found in recorded history:

• Votive jar dedicated to grandmother
• Claimed birth year of 610 CE
• Peony seed anecdote dated to seven years of age
• A Chinese ambassador named Lin Fang serving as her tutor
• Astronomer princess
• Solar eclipse prediction
• Begged her father to build an observatory
• Method of observation from Cheomseongdae

The problem with most of these claims are, at base, that they are not found in historical records of Seondeok and Cheomseongdae found mainly in the Samguk Sagi (三國史記, History of the Three Kingdoms) and Samguk Yusa (三國遺事, Stories from the Three Kingdoms). Some of the problems are elaborated in more detail below:

Seondeok's years of rule and death are recorded (r. 632-647, d. 647), but no birth year is found on record. Yet the Cosmos Magazine article states: “She was born in 610 CE,” while the Seondeok chapter of Unforgotten Sisters makes two conflicting claims in marking her birth year correctly in the title as unknown and then, just a few lines down near the beginning of the text, claiming her birth year as 610 AD.

The Cosmos Magazine article states:

At seven, for example, a box of peony seeds arrived at the Court, from China. ... Her observation about the peonies’ lack of smell proved correct – one illustration among many of her intelligence.

The anecdote itself is well-known and attested in both the Samguk Sagi and Samguk Yusa, but no record dates this specifically to when she was seven years of age as claimed by Bernardi. The Samguk Sagi states she made this prediction as a princess while her father was still king but does not pinpoint the age, while the Samguk Yusa states the episode took place during her own reign when she was likely much older than seven.

The Cosmos Magazine article 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:

別記云是王代鍊石築瞻星臺 (A separate record states that it was in this King[ 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

The Cosmos Magazine article states:

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. In fact there is dispute in the Korean historical and archaeological communities over whether the building was used for astronomical observation at all, though I do not expect most outside a very specific niche of expertise to know about this disagreement.

If Bernardi can present a historical record in support of this assertion, 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.

• 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 or the Cosmos Magazine article 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.

Interestingly, Bernardi's assertion that an astronomer using Cheomseongdae laid on their back and watched the heavens through four domes is one of the few claims 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.

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.

• Almost all the dubious 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.