Pith. sign in

REVIEW 3 major objections 5 minor 18 references

New Insights into the Nature and Orbital Motion of Aristotle's Comet in 372 BC

T0 review · 3 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read Aristotle's 372 BC comet is identified as the Kreutz progenitor with a January 20 perihelion.

desk verdict A careful historical test of a model-derived Kreutz orbit that lands on Jan 20, but the date is only as solid as the adopted elements, which the paper does not vary. read the letter →

arxiv 2507.15228 v1 pith:GEFWGVQ2 submitted 2025-07-21 astro-ph.EP

Zdenek Sekanina This is my paper · ORCID
classification astro-ph.EP
keywords Aristotle'scometKreutzsungrazersperiheliondate372BCMeteorologicaorbitdeterminationplasmatailancientastronomy
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper tries to fix the perihelion date of Aristotle's 'great comet' of 372 BC and to show that the comet was the ancestor of the Kreutz sungrazer family. The author treats five orbital elements from an earlier model of the Kreutz system as fixed and treats the perihelion time as the one free parameter. Aristotle's three remarks—the comet set just before the Sun one evening and immediately after it the next, it receded to Orion's belt and dissolved, and its tail spanned a third of the sky—are turned into quantitative constraints. Those constraints single out January 20, 372 BC as the most probable perihelion date, making January 21 the likely first naked-eye sighting and giving a visibility span of more than ten weeks. If the identification is right, a specific ancient eyewitness event becomes the direct progenitor of a comet family still active today.

What carries the argument

The load-bearing object is the orbit in Table 1: five osculating elements (argument of perihelion 68°.35, ascending node 345°.43, inclination 141°.32, perihelion distance 0.0068 AU, eccentricity 0.99992) produced by the contact-binary model of the Kreutz system—a model in which the family descends from a nucleus made of two contacting lobes—and treated as firmly established. The perihelion time is the only element left free, sampled at five dates from January 1 to March 22. The mechanism that carries the argument is spherical-triangle sunset geometry at Athens, combined with a dust-comet phase function, a naked-eye limiting-magnitude algorithm, and a projection formula that converts an observed tail angle into a spatial length along the radius vector.

What would settle it

Recompute the 372 BC comet's path with an independent Kreutz-family model that does not rely on the contact-binary assumption, and check whether the orbit still puts the comet within a few tenths of a degree of the setting Sun on a mid-to-late January evening and at Orion's belt in early April; if not, the January 20 solution fails. A single independent ancient record, such as a Chinese observation showing the comet in a different sky position on the same dates, would likewise falsify the fit.

Watch

Extended reading notes

Core claim

The paper's central claim is that Aristotle's narrative is tight enough to determine the perihelion passage to a specific day: January 20, 372 BC, with two solutions (perihelion at 20.75 or 20.63 UT) less than three hours apart. Under this solution the 'first day' is the day the comet's head was either hidden behind the Sun's disk or practically in contact with it, and the 'next day' is the first day after perihelion, when the comet set only 15 to 45 seconds after the Sun. The same orbit carries the comet across Orion's belt on April 3–4, matching Aristotle's statement that it receded to the belt and disappeared there, and a 60-degree tail seen in the last days of January corresponds to a plasma tail roughly 0.8 AU long. The author takes this convergence as support for identifying the 372 BC comet as the giant progenitor of the Kreutz sungrazers.

Load-bearing premise

The orbit used for the comet is assumed to be exactly right, even though it comes from an earlier model; if it is wrong, the match to Aristotle's words is coincidental and the January 20 perihelion date is unsupported.

Editorial extensions

If this is right

  • If the January 20 perihelion is correct, Aristotle's 'first day' has a physical explanation: the comet's head was behind or grazing the Sun's disk, and the 'next day' was the first day after perihelion.
  • The same orbit crosses Orion's belt on April 3 or 4, so the constellation statement can be checked independently of the setting-time argument.
  • A 60-degree tail seen in late January implies a plasma tail about 0.8 AU long, comparable to later great Kreutz sungrazers such as C/1843 D1, C/1882 R1, and C/1965 S1.
  • The comet would have stayed visible to the naked eye for more than 70 days, longer than C/1843 D1 or X/1106 C1, suggesting it did not fragment as heavily at perihelion as C/1882 R1.
  • These results support placing the 372 BC comet at the root of the Kreutz family, connecting a documented ancient event to a modern sungrazer population.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • A consequence the paper leaves implicit is that the January 20 date provides a target for independent dynamical checks: a Kreutz-system integration that does not assume the contact-binary pairing should still place the comet within a few days of January 20.
  • The paper's outcome depends on one contested translation ('receded' vs 'rose'), which suggests that re-examining other ambiguous ancient comet records with the same sunset-setting and constellation-crossing tests could yield similarly sharp dates.
  • If the identification holds, the 372 BC event would anchor the long-term orbital evolution and fragmentation history of the Kreutz family, including predicted return windows for possible first-generation fragments.
  • A testable extension is to apply the same fixed-orbit method to other historical sungrazers and see whether their reported setting behavior and sky paths select unique perihelion dates as they do here.
Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. The paper confronts a previously computed set of orbital elements for Aristotle's comet (from the author's Kreutz contact-binary model, Sekanina & Kracht 2022) with three statements in Aristotle's Meteorologica: (i) the comet was not seen on the first day because it set before the Sun but was seen the next day, being a very small distance behind the Sun and setting immediately; (ii) it receded as far as Orion's belt and there dissolved; and (iii) its tail extended over a third of the sky. Through geometric calculations for an Athenian observer, the paper derives a most-probable perihelion date of January 20, 372 BC (cases "15" and "45" giving perihelion times Jan 20.75 and Jan 20.63 UT), argues that the comet's head was occulted by or in near contact with the Sun on the first day, finds that a January 20 to February 10 perihelion window is consistent with the Orion's-belt crossing, interprets the 60° tail as a plasma tail of roughly 0.8 AU, and concludes that Aristotle's comet was the progenitor of the Kreutz sungrazers.

Significance. If the central inference is robust, this would provide a historically important anchor for the Kreutz sungrazer system and demonstrate a clever use of relative-setting geometry to date an ancient comet observation to within a day. The paper's strengths are its transparent geometric tests, the explicit exploration of an alternative hypothesis in Section 5.4, and its frank acknowledgments of translation ambiguity and the unknown observing site in Sections 4 and 9. It also makes falsifiable predictions, including a full ephemeris (Table 13) and a predicted tail length of roughly 0.8 AU. The significance is conditional, however, because the entire edifice rests on an imported set of orbital elements whose uncertainty is not quantified and on several interpretive conventions that are adopted rather than tested.

major comments (3)
  1. [Section 4, Table 1] The five orbital elements (ω, Ω, i, q, e) are imported from the author's contact-binary model (Sekanina & Kracht 2022) and declared "firmly established," but no sensitivity analysis over these elements is presented. The near-Sun setting geometry that yields the January 20 perihelion date (Tables 2–5 and Eqs. (1)) depends sensitively on the orientation elements and on q; a change of even about a degree in ω or Ω would shift the comet's projected path relative to the Sun at sunset and could eliminate the 15–45 s solution. The Cooper–Pingré intervals quoted in Table 1 are too broad (ω = 60°–180°, Ω = 302°–3°, i < 150°, q "very small") to constitute an independent validation. Please provide a sensitivity analysis over the Table 1 elements, or an independent determination, before presenting the January 20 date as the paper's central result.
  2. [Section 5.3 and Section 9] The inference that the "first day" and the "next day" are exactly 24 hours apart is an interpretive assumption that the paper itself questions in Section 4 ("One also could question whether the next day was indeed meant 24 hours later"), yet all subsequent tables assume it. If bad weather intervened, the "next day" could be two or more days after the "first day," and the simultaneous-setting solution would shift accordingly. Similarly, the adopted conventions that "setting immediately" means 15–45 s after last contact and that the observer is in Athens (Section 9 admits the site is unknown and could be Stagira or Atarneus) are arbitrary at the level of the claimed precision. Please quantify the sensitivity of the January 20 date to a 1–2 day gap and to a shift of the observing site by the distances mentioned.
  3. [Appendix A and Section 5.4] The light-curve model (Eqs. (A-1)–(A-5)) is built from the assumption that Aristotle's comet is the Kreutz progenitor, with absolute magnitudes extrapolated from the 1843 and 1882 comets and Nfrg = 3 motivated by the author's predicted fragment periods. The visibility arguments in Tables 5–7, and especially the rejection of the alternative hypothesis in Section 5.4, thus depend on the very hypothesis being tested. This is not circular for the geometric perihelion-time inference, but it is circular for the claim that the brightness behavior independently supports the model. Please state this limitation explicitly and test whether the "first day invisible" condition is satisfied for a substantially fainter or brighter comet, for example with H0− in the range 2–5.
minor comments (5)
  1. [Section 5.3, Table 4] The table mixes formats for time entries (e.g., "15:28.09" for the last contact on January 16), which appears to be a typographical error; please use consistent sexagesimal notation.
  2. [Section 7.1, Section 7.2, Appendix A, Section 9] There are several typographical errors that should be corrected in proof: "swiching" (Section 5.3), "below be performed" (Section 7.1), "beem" (Section 7.1), "pariod" (Section 7.2), "plamets" (Appendix A), and "constraning" (Section 9).
  3. [Section 2] The discussion of the two English translations is informative, but the paper does not provide the original Greek text or a discussion of the key word's semantics; adding the Greek term would strengthen the choice of "receded" over "rose."
  4. [Figures 1–3] The star maps are extremely dense and the position-number labels are difficult to read; consider enlarging the relevant regions near Orion's belt in separate insets.
  5. [Section 5.2] The statement that "for the Sun's disk to set it takes about three minutes between the first and last contacts with the horizon" is not precisely consistent with the Table 4 contact times, which span about three minutes for some dates but only about two minutes for others; please reconcile the estimate with the computed values.

Circularity Check

1 steps flagged · score 2.0 of 10

The perihelion-date inference is not circular; the adopted orbit is tested against Aristotle's independent text. A minor self-referential element appears in the light-curve calibration used for visibility checks.

  1. other [Appendix A, Eq. (A-3) and surrounding text; applied in Tables 3, 5, 7; final conclusion in Section 9.]
    "In the absence of a better estimate, I adopt Nfrg = 3, which includes the progenitor of the Kreutz system in AD 363 plus two non-Kreutz fragments of the Great Comet of 372 BC."

    The brightness model used to 'predict' apparent magnitudes (e.g., Table 5 gives about -11.4 for the Jan 20/21 case) is calibrated by assuming Nfrg = 3, which already presupposes that the 372 BC comet fragmented into the Kreutz-system progenitor plus two non-Kreutz fragments. The absolute magnitude H0^- = 1.5 is similarly extrapolated from the 1843 and 1882 Kreutz sungrazers under the same progenitor hypothesis. Thus the visibility consistency check is conditioned on the very Kreutz-progenitor conclusion the paper says its results 'strengthen.' This is self-referential, but it is not the basis of the January 20 perihelion date, which follows from geometric setting/sunset timing using the adopted orbit.

full rationale

The paper's central derivation—perihelion on January 20, 372 BC—is not circular. The five orbital elements in Table 1 are imported from Sekanina & Kracht (2022), but they are not fitted to Aristotle's text; the paper confronts them with the independent historical statements in the Meteorologica. The restrictive condition that the comet set before the Sun on one evening and just after the Sun on the next is converted, via Tables 2-5, into a geometric constraint on the perihelion time, yielding January 20. The Orion's-belt crossing and the 60-degree tail are likewise computed from the adopted orbit and compared with Aristotle's remarks. This is a genuine test: if the adopted elements were wrong, the agreement would disappear. The paper's self-citations are numerous, but the load-bearing use of Sekanina & Kracht (2022) is not circular because that prior work derived the elements from the contact-binary model and Kreutz-system integrations, not from the historical account being tested. The only self-referential element is the light-curve calibration in Appendix A, where Nfrg = 3 and the magnitude scale assume the Kreutz-progenitor link; this affects the visibility check but not the geometric perihelion-time determination. The Cooper-Pingre intervals, while broad, provide an external historical bracket rather than a fitted constraint. On balance, the paper shows no significant circularity in its main inference, only a minor self-referential calibration in an auxiliary visibility model.

Assumptions & free parameters 6 free parameters · 8 assumptions · 0 invented entities

The central claim depends on the model-derived orbit and on a chain of interpretive assumptions about a 2,400-year-old text. The light curve adds several parameters adopted from the author's prior work. No new physical entities are introduced.

free parameters (6)
  • H0- = 1.5
    Pre-perihelion absolute magnitude adopted by extrapolation from descendants; used in visibility predictions (Appendix A).
  • n- = 4.0
    Pre-perihelion brightness power law index assumed equal to Ikeya-Seki; used in light curve (Appendix A).
  • Nfrg = 3
    Adopted number of major fragments at perihelion; determines post-perihelion fading rate n+ via Equation (A-3).
  • n+ = 3.8
    Post-perihelion fading power law index computed from Nfrg=3 via Equation (A-3); affects visibility after perihelion.
  • H0+ = 0.4
    Post-perihelion absolute magnitude from continuity at perihelion; used in post-perihelion visibility calculations.
  • case delay = 15 s and 45 s
    Interpretation of 'setting immediately' as 15 or 45 seconds after the Sun's last contact; the two cases bracket the inferred perihelion time on January 20.
assumptions (8)
  • domain assumption The orbital elements in Table 1 (Sekanina and Kracht 2022) are firmly established for Aristotle's comet
    The entire test against Aristotle's text assumes these model-derived elements are correct; Section 4 calls them firmly established.
  • domain assumption Webster's English translation of Aristotle's Meteorologica is the correct rendering, including 'this comet receded as far as Orion's belt'
    The Orion's belt constraint depends on this translation; the alternative translation says 'it rose', which would refer to the tail, not the comet's motion (Section 2).
  • ad hoc to paper The 'next day' in Aristotle's account means exactly 24 hours after the 'first day'
    Section 4 and 9 assume a 24-hour gap; if cloudy nights intervened the constraints change.
  • domain assumption The observer was at Athens (latitude 38.00 N)
    Section 9 admits the observing site is indeterminate and Athens is used as a representative Greek location; setting times depend on latitude.
  • standard math Atmospheric refraction is ignored
    Footnote 4 states refraction affects all objects equally and is ignored; this is a standard approximation for these altitude differences.
  • domain assumption The comet's tail extends along the antisolar radius vector
    Used to convert the 60-degree observed length to a physical length via Equation (4); the paper notes plasma tails generally follow this direction.
  • domain assumption The Marcus (2007) phase function and the r^-n brightness law apply to Aristotle's comet
    The adopted light curve in Appendix A rests on this empirical model for dusty comets.
  • domain assumption The Schaefer limiting magnitude algorithm applies to comet heads
    Appendix B applies a stellar visibility algorithm to the comet's head, justified by the compact appearance of sungrazers.

how reviews work

0 comments
Cite this review

Pith. "Pith review of New Insights into the Nature and Orbital Motion of Aristotle's Comet in 372 BC." pith.science (2026). https://pith.science/paper/GEFWGVQ2

@misc{pith2026250715228,
  author       = {Pith},
  title        = {Pith review of: New Insights into the Nature and Orbital Motion of Aristotle's Comet in 372 BC},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/GEFWGVQ2}},
  note         = {Machine review of arXiv:2507.15228}
}
read the original abstract

Extending the investigation of the presumed primordial comet as part of continuing work on a new model of the Kreutz sungrazer system, I confront a previously derived set of orbital elements with Aristotle's remarks in his Meteorologica to test their compatibility and determine the comet's perihelion time. The two translations of the treatise into English that I am familiar with differ at one point substantially from each other. Unambiguously, the year and season of the comet's appearance was early 372 BC (or -371). From Aristotle's constraint on the comet's setting relative to sunset, I infer that the probable date of perihelion passage was January 20, a date also consistent with the vague remark on frosty weather. On the day that Aristotle claims the comet was not seen, its head may have been hidden behind the Sun's disk or in contact with it. The observation that the `comet receded as far as Orion's belt, where it dissolved' is being satisfied by the tested orbit if the perihelion was reached between January 20 and February 10. Aristotle's third statement, which describes the tail as a streak 60 degrees in length, suggests a plasma feature stretching in space over 0.8 AU. The dust tail was developing more gradually and it was all that could be seen from the comet when it was approaching Orion's belt in early April. The comet was seen over a period of more than 10 weeks. The results of this study strengthen the notion that Aristotle's comet indeed was the gigantic progenitor of Kreutz sungrazers.

Figures

Figures reproduced from arXiv: 2507.15228 by the authors.

Figure 1
Figure 1. Predicted path of Aristotle’s comet near perihelion relative to the Sun’s disk, with the perihelion time assumed between January 1 and March 22, 372 BC at a 20-day step. The solid dots are the comet’s offset positions at times, measured in hours from perihelion (negative = before, positive = after), in the equatorial coordinate system (equinox J2000) and predicted for Athens, Greece (longitude 23◦.63 E, latitude +38… view at source ↗
Figure 2
Figure 2. Predicted post-perihelion path of Aristotle’s comet as seen from Athens in 372 BC (equinox J2000). The star maps refer to an assumed perihelion time at 0 UT on January 1 (top), January 21 (middle), and February 10 (bottom). The comet’s positions on standard dates are marked by large open circles and position numbers that are explained in [PITH_FULL_IMAGE:figures/full_fig_p010_2.png] view at source ↗
Figure 3
Figure 3. Predicted post-perihelion path of Aristotle’s comet as seen from Athens in 372 BC (equinox J2000). The star maps refer to an assumed perihelion time at 0 UT on March 2 (left) and March 22 (right). As in [PITH_FULL_IMAGE:figures/full_fig_p011_3.png] view at source ↗
Figures from the paper (4 more)
Figure 4
Figure 4. Figure 4: The Great March Comet of 1843 in the constellation of Cetus seen from Cape Town in the evening of March 4, 1843 shortly before it was setting at 18:36 UT. The comet was 4.86 days after perihelion at a solar elongation of about 17◦ . According to his di￾ary, C. Piazzi S…
Figure 5
Figure 5. Figure 5: Length of the plasma tail of Aristotle’s comet in space, predicted on the assumption that the tail extends along the radius vector, vs an (unknown) time at which its observed length was 60◦ (or “a third part of the sky”) according to Aristotle. The dates of January 21 …
Figure 6
Figure 6. Figure 6: The modeled schematic appearance of the dust tail of Aristotle’s comet on January 23.65 and 25.65 UT, shortly after sun￾set, in case “15” (equinox J2000). The tail contours are depicted by three syndynames, showing particle trajectories affected by the radiation-pressu…
Figure 7
Figure 7. Figure 7: Aristotle’s comet about the time of its final sighting at Orion’s belt, as it may have appeared on April 3.76 UT, 372 BC, at the end of astronomical twilight at Athens. Its elevation was then 12◦.5. Its head (large open circle), whose predicted location was less than 2…

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

18 extracted references · 12 canonical work pages

  1. [1]

    Barrett, A. A. 1978, J. Roy. Astron. Soc. Canada, 72, 81

    work page 1978

  2. [2]

    1980, Vistas Astron., 24, 59

    Hasegawa, I. 1980, Vistas Astron., 24, 59

    1980

  3. [3]

    2001, Publ

    Hasegawa, I., & Nakano, S. 2001, Publ. Astron. Soc. Japan, 53 , 931

    2001

  4. [4]

    1962, Vistas Astron., 5, 127

    Ho, P.-Y. 1962, Vistas Astron., 5, 127

    1962

  5. [5]

    2022, Seism

    Katsonopoulou, D., & Koukouvelas, I. 2022, Seism. Res. Lett ., 93, 2401

    work page 2022

  6. [6]

    2011, Annu

    Kolia, E. 2011, Annu. Brit. School Athens, 106, 201

    work page 2011

  7. [7]

    Kronk, G. W. 1999, Cometography, Volume 1: Ancient–1799

    work page 1999

  8. [8]

    Marcus, J. N. 2007, Int. Comet Quart., 29, 39 Mart ´ ınez, M. J., Marco, F. J., Sicoli, P., & Gorelli, R. 2022, Icarus, 384, 115112 Pingr´ e, A. G. 1783, Com´ etographie ou Trait´ e historique et th´ eorique des com` etes. Tome Premier. Paris: L’Imprimerie Royale

    work page 2007

Show all 18 references
  1. [9]

    Schaefer, B. E. 1993, Vistas Astron., 36, 311

    1993

  2. [10]

    Schaefer, B. E. 1998, Sky Tel., 95, 57; Java Script code by L. B ogan at https://www.bogan.ca/astro/optics/vislimit.html

    1998

  3. [11]

    2009, The Greatest Comets in History: Broom Sta rs and Celestial Scimitars

    Seargent, D. 2009, The Greatest Comets in History: Broom Sta rs and Celestial Scimitars. New York: Springer Science+Busin ess

    2009

  4. [12]

    2002, Astrophys

    Sekanina, Z. 2002, Astrophys. J., 566, 577

    2002

  5. [13]

    2021, eprint arXiv:2109.01297

    Sekanina, Z. 2021, eprint arXiv:2109.01297

    2021 arXiv

  6. [14]

    2022a, eprint arXiv:2211.03271

    Sekanina, Z. 2022a, eprint arXiv:2211.03271

    arXiv

  7. [15]

    2022b, eprint arXiv:2202.01164

    Sekanina, Z. 2022b, eprint arXiv:2202.01164

    arXiv

  8. [16]

    2023, eprint arXiv:2310.05320

    Sekanina, Z. 2023, eprint arXiv:2310.05320

    2023 arXiv

  9. [17]

    2025, eprint arXiv:2505.14662

    Sekanina, Z. 2025, eprint arXiv:2505.14662

    2025 arXiv

  10. [18]

    2022, eprint arXiv:2206.10827 W arner, B

    Sekanina, Z., & Kracht, R. 2022, eprint arXiv:2206.10827 W arner, B. 1980, Mon. Not. Astron. Soc. South Africa, 39, 69 W ebster, E. W. 2004, Meteorology. Translation of Aristotle ’s Mete- orologica, Book 1.6. Adelaide: University of Adelaide eBoo ks

    2022 arXiv

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.