[Paper Review] New sunspots and aurorae in the historical Chinese text corpus? Comments on uncritical digital search applications

D.L. Neuhaeuser, R. Neuhäeuser+1 more|arXiv (Cornell University)|Nov 14, 2017

Historical Astronomy and Related Studies4 references4 citations

TL;DR

This paper critically evaluates digital search methods used to identify historical Chinese sunspot and auroral records, revealing widespread misidentifications due to uncritical keyword matching. The authors demonstrate that most alleged new records are not true aurorae or sunspots, but rather halos, comets, or other phenomena, and caution against using such flawed datasets for solar activity reconstructions.

ABSTRACT

We review some applications of the method of electronic searching for historical observations of sunspots and aurorae in the Chinese text corpus by Hayakawa et al. etc. However, we show strong shortcomings in the digital search technique as applied by them: almost all likely true sunspot and aurora records were presented before (e.g. Xu et al. 2000), which is not mentioned in those papers; the remaining records are dubious and often refer to other phenomena, neither spots nor aurorae (this also applies to Hayakawa et al. 2017c). Most of the above publications include very few Chinese texts and translations, and their tables with abbreviated keywords do not allow the reader to consider alternative interpretations (the tables also do not specify which records mention night-time). We have compared some of their event tables with previously published catalogs and found various discrepancies. There are also intrinsic inconsistencies, misleading information (lunar phase for day-time events), and dating errors. We present Chinese texts and translations for some of their presumable new aurorae: only one can be considered a likely true aurora (AD 604 Jan); some others were selected on the sole basis of the use of the word "light" or "rainbow". Several alleged new aurorae present observations beside the Sun during day-time. There are well-known comets among their presumable aurorae. We also discuss, (i) whether "heiqi ri pang" can stand for black spot(s) "on one side of" or "beside" the sun, (ii) aurora color confusion in Hayakawa et al. (2015, 2016), and (iii) whether "white" and "unusual rainbows" can be aurorae.

Motivation & Objective

• To evaluate the reliability of automated digital searches for historical Chinese sunspot and auroral records in recent studies.
• To identify systematic flaws in keyword-based electronic searches that lead to false positives and misinterpretations.
• To highlight that many purported new records are actually non-auroral phenomena such as halos, comets, or weather events.
• To emphasize the necessity of contextual, terminological, and chronological analysis in interpreting historical astronomical reports.
• To caution researchers against using uncritically derived datasets for solar activity reconstructions, advocating for integration with established scholarship.

Proposed method

• Comparing newly claimed auroral and sunspot records from Hayakawa et al. (2015–2017), Kawamura et al. (2016), and Tamazawa et al. (2017) with previously published catalogues.
• Analyzing original Chinese texts and their English translations to assess whether alleged records meet established criteria for aurorae or sunspots.
• Evaluating lunar phase correlations in reported events, particularly the spurious peak in auroral sightings around full moon, which contradicts known auroral behavior.
• Assessing terminology such as 'heiqi ri pang', 'bai ni', and 'hong' for potential misinterpretation as aurorae or sunspots.
• Applying critical historical exegesis to contextualize reports, including time of day, weather conditions, and celestial positioning.
• Cross-referencing claims with known astronomical phenomena like halos, comets, and airglow to rule out non-auroral explanations.

Experimental results

Research questions

• RQ1 To what extent do digital keyword searches in historical Chinese texts reliably identify authentic auroral and sunspot observations?
• RQ2 Why do certain studies report a peak in auroral sightings around full moon, contrary to known auroral behavior?
• RQ3 How do terminological ambiguities (e.g., 'bai ni', 'hong', 'heiqi ri pang') lead to misclassification of non-auroral phenomena as aurorae?
• RQ4 What proportion of allegedly new auroral records can be verified as genuine based on historical, astronomical, and meteorological criteria?
• RQ5 To what extent do automated searches compromise the credibility of solar activity reconstructions when applied without contextual analysis?

Key findings

• Most of the alleged new auroral records from Hayakawa et al. (2015–2017) and Kawamura et al. (2016) are not genuine aurorae but misidentified halos, comets, or other atmospheric phenomena.
• The reported auroral sightings in Hayakawa et al. (2015) and Kawamura et al. (2016) show a statistically significant peak around full moon, which is inconsistent with the known diurnal and geomagnetic cycle dependence of aurorae.
• Only one of the eleven presumable new auroral events from Tamazawa et al. (2017) can be considered a likely true aurora (AD 604 Jan), while others are halos or misclassified phenomena.
• The use of terms like 'light' or 'rainbow' as proxies for aurorae leads to false positives, as these terms refer to various non-auroral atmospheric optics.
• Several records labeled as aurorae are actually comets, including one cited in the context of AD 993/4, which is not an aurora but a known comet.
• The study confirms that previous catalogues, such as those by Silverman (1998) and Usoskin et al. (2013), also contain misidentified events, underscoring the need for critical re-evaluation of digital search results.