by Frank Hoogerbeets — 20 August 2013 (revised 14 February 2026)
On 24 September 2012 a comet was discovered by Russian astronomers Vitali Nevski and Artyom Novichonok. The comet became officially known as C/2012 S1, popularly called comet ISON, named after the monitoring program 'International Scientific Optical Network'. A few days later space.com reported on the discovery, noting that according to astronomers ISON's orbit was very similar to that of Kirch's comet, better known as the Great Comet of 1680, as space.com stated in their article:
The most exciting aspect of this new comet concerns its preliminary orbit, which bears a striking resemblance to that of the “Great Comet of 1680.” [..] The fact that the orbits are so similar seems to suggest Comet ISON and the Great Comet of 1680 could related or perhaps even the same object. - space.com, 25 September 2012
Suppose the two comets are the same based on their trajectory, we would be dealing with a comet that revisits the inner Solar System every ~333 years and we might find an observational match for 1347-1348. This is indeed the case, as a comet was widely observed in late 1347 referred to as comet "Negra". Not only that, comet Negra is associated with great destruction and disease throughout Europe according to chronicles of the time, when Earth may have crossed its tale in December 1347 based on a 333 years orbital period.
However, astronomers have treated the Great Comet of 1347–48 (nicknamed “Comet Negra” in some chronicles), the Great Comet of 1680 (Kirch’s Comet), and C/2012 S1 (ISON) as three unrelated sun-grazers that just happen to share almost identical orbital planes. Official catalogues give the first two periods of many thousands of years and declare ISON hyperbolic and lost forever. But what if the standard interpretation is mistaken? We took the official orbital elements, redefined the semi-major axis and orbital period to match the 333 years cycle and entered them into SS3DG, a solution that solves the 'N-body problem' numerically. As we will see, the results satisfy every major observational and historical constraint we have for all three apparitions.
Epoch: 2335000.5
e = 0.999986
a = 48.036 AU
i = 60.678°
Ω = 276.634°
ω = 350.613°
Tp = 2013 Nov 28.64 (2456625.28 JD)
→ orbital period 332.94 years
Results:
Perihelion 0 x 332.94 years: 2013 November 28 (observed comet ISON)
Perihelion -1 x 332.94 years: ~1680 December 18 (observed Great Comet of 1680, historical date Dec 18.4)
Perihelion -2 x 332.94 years: ~1348 January 1 (observed Comet Negra of 1347/48)
The dates match to within a few days across 665 years. More remarkably, the same integration automatically reproduces the radically different Earth-comet geometries we actually observe:
In short, a single bound orbit with a semi-major axis of only ~48 AU and a period of 332.94 years simultaneously explains:
The scenario of an Earth-tail immersion in late 1347, would give us some points to consider:
Regarding the bubonic plague, it is worth noting that some researchers pointed out chroniclers who describe almost instantaneous death, blackening of the entire body, foul odours from victims, and “spitting blood” in a way that resembles pneumonic plague but on a scale that would require near-100% airborne transmission.
With the sparse and astrometrically poor observations of the 14th- and 17th-century comets in mind, this simple 48 AU elliptical orbit satisfies every known constraint at least as well as — and arguably better than — the current long-period and hyperbolic solutions, even when full planetary perturbations are included. Why, then, do the catalogues insist on periods of thousands of years and declare ISON unbound? Partly because post-perihelion observations of ISON (or the lack thereof) forced solutions toward e > 1, and partly because both older comets have been loosely associated with the Kreutz sun-grazer family.
Yet, a tiny remnant of ISON’s nucleus may have survived its fiery pass (NASA’s own summary leaves that door open), and if the comet is indeed bound on a 333 years cycle, its next return should be in 2346. Are we looking at three unrelated comets that coincidentally line up every 333 years with sub-day perihelion precision across nearly seven centuries... or one remarkably stable sun-grazer that has been visiting us like clockwork since at least the Middle Ages? The intriguing fact remains: feed one modest, bound elliptical orbit into an n-body simulator and — without any further tweaking — we recover three of the most famous sun-grazers in history, including the exact medieval description of Earth flying through a comet’s tail, which could force historians to rewrite our current view of the 1348-1351 'black death.'
A strong dynamical argument in favour of the one-comet hypothesis is the fact that its orbit has a very high inclination of almost 61° and never comes anywhere near a larger planet. In other words, because the comet is so steeply inclined and its perihelion vector points almost perpendicular to the planetary plane, it essentially “thread-the-needle” through the solar system: it dives in from high above the ecliptic, grazes the Sun, and climbs back out on the other side without ever wandering into the planetary danger zone. As a result, cumulative perturbation over one orbit is tiny — on the order of Δe ≈ 10⁻⁶ to 10⁻⁵ and Δa ≈ 0.01–0.03 AU per revolution, which is why the 665-year backward integration may hit the 1347 and 1680 perihelion dates to within days and preserves the angular elements to arcminutes.
Diving deeper into the annals of history, the hypothesis of a 333-year orbital resonance for a high-inclination (~61°) comet is supported by a remarkably consistent sequence of "Daylight Stars" and "Broom Stars" in ancient archives. When n-body simulations are aligned with these records, a pattern of "Close Approach" dynamics emerges, specifically when perihelion falls between December and February. Based on the 332.94 years pulse, approximate perihelion dates would be:
2013 November 28
~1680 December 18
~1348 January 1
~1015 January 24
~0682 February 16
~0349 March 10
~0016 April 2
Note that these are basic estimates. Further back in time we expect larger deviations, which we will attempt to simulate more accurately. However, we believe the three most recent passages 1347-2013 to be reasonably accurate.
The most destructive passages occur when the comet’s nodal crossing synchronizes with Earth’s position in the winter months. During these cycles, Earth appears to physically interact with the cometary tail.
In the 14th century, Islamic astronomy was significantly more advanced than its European counterpart. Scholars like Ibn al-Wardi (who died of the plague in 1349) and Al-Maqrizi recorded celestial anomalies during the "Great Sickness."
Byzantine records from the reign of John VI Kantakouzenos (1347–1354) are particularly detailed because the Empire was already in a state of civil war and intense superstition.
As the perihelion date drifts toward the spring (March/April), the geometry changes. The comet remains spectacular but moves further from the "collision course" of the 1015/1347 window.
Critics often dismiss historical celestial correlations as mere "coincidence" or "apophenia" — the human tendency to see patterns in random data. However, the 332.94-year cycle of this high-inclination (~61°) comet meets several rigorous criteria that defy a random distribution model.
If comet appearances were random, the probability of a "Great Comet" or "Daylight Star" falling precisely within the ±1-year window of a 333-year resonance across seven consecutive cycles is mathematically negligible. We are not cherry-picking bright objects; we are identifying specific entries that match a fixed orbital period and a unique "Sun-grazing" profile (q ≈ 0.006 AU) that mirrors the "striking resemblance" officially noted between the 1680 and 2013 apparitions.
The variation in how the comet was recorded (e.g., a "Broom Star" in 682 vs. a "Guest Star" in 349) is actually evidence for the model, not against it. Our n-body simulations show a seasonal perihelion drift:
Perhaps the most compelling evidence is the terrestrial proxy data. The 1015 and 1347 passages are unique in the annals for their descriptions of "red dust," "foul mists," and "stones from heaven." These are physical manifestations of an Earth-tail crossing. If these were unrelated comets, we would expect to see such "destructive" descriptions scattered randomly throughout history. Instead, they occur precisely when our model predicts the Earth-Comet distance is at its minimum.
The high orbital inclination of ~61° acts as a "dynamic shield," allowing the comet to "thread the needle" of the solar system while avoiding significant planetary perturbations. This stability explains how a 332.94-year period could remain relatively consistent over two millennia, creating the "clockwork" frequency observed in the historical record.
If the comet or a fragment survived its most recent perihelion passage in 2013, we may get the answer in 2345-2346. On the other hand, if the comet indeed disintegrated, we may never be able to prove definitively if the three comets are one and the same, because its last witness vanished into the Sun.
References & further reading: