Return of a Relic ~ Sungrazer Comet 2026 A1 (MAPS) Back After Sixteen Centuries

It had to happen. In our last post, The Dangerous Lives of Sungrazer Comets [1], we reported that from all the studies of sungrazers to date, “it’s plain that there are more astonishing sungrazing comets to come.” Now, images taken on January 13^th of this year from Atacama, Chile, have revealed the inbounding of another Kreutz sungrazer comet, C/2026 A1 (MAPS), the third discovered from the ground in the 21^st century. The first was C/2011 W3 (Lovejoy) – which lost its head a few days after its hair-raising trip round the Sun. The second, C/2024 S1 (ATLAS), was a dwarf sungrazer that JPL/Caltech Senior Research Scientist Zdenek Sekanina called a “flop.” But now we have MAPS, heading to perihelion on April 4^th of this year. This one could be a thriller. Dr. Sekanina went on to say, “it is hoped that the third try will be more successful.”

Dr. Sekanina forwarded me his new paper on this sungrazer, “New Kreutz Sungrazer C/2020 A1 (MAPS): Third Time’s The Charm?” [2], which I’ll talk about below. Two things immediately stand out from it. First, MAPS holds the hands-down record for long-distance, pre-perihelion detection: 81.4 days. For comparison, Ikeya-Seki (C/1965 S1) was captured 32.4 days before perihelion; ATLAS 30.9 days before perihelion. Matched against other sungrazers, MAPS has a much longer observed orbital arc, from which its orbital elements can be computed with ever higher precision. The higher the precision the better for discerning MAPS’s orbital history and properly placing it in the Kreutz sungrazer family tree. The longer pre-perihelion time also allows more opportunity to monitor MAPS’s magnitude variations and physical characteristics.

The second matter that jumps out from Dr. Sekanina’s study is of even greater interest: It has an immensely long orbital period. The comet’s ‘barycentric original period’ appears to be about 1,672 years. A body’s barycentric original period is one that’s been corrected for the effects of planetary perturbations and reduced to the mass center (the ‘barycentric center’) of the solar system [3].

Over 1,600 years! This is way longer than the typical seven or eight century orbital period of many Kreutz sungrazers. This is an old comet, in the sense of a relic, relative to its cousins. Dr. Sekanina notes: “If the outcome of the MAPS comet’s current, preliminary orbital computations is confirmed in the future, when a longer orbital arc is available, we are in for a big surprise because the object appears to have had a very interesting history.” If you’ve read my Dangerous Lives article, you’ve probably guessed what he means. He means that we can likely fit comet MAPS into an interesting place on the sungrazer family tree and determine when it broke apart as a fragment of Aristotle’s comet.

Sungrazer update

The science of these comets is captivating, cutting edge, and continues to evolve: a scientific and human-interest mystery that combines chronicles of comet apparitions with the challenge of decoding their nature and orbits. Comets tie us to our past. Any reader who saw Comet Lovejoy in 2011, or even last October’s C/2024 S1 (ATLAS), may be surprised to learn that they saw pieces of the very same comet that so startled Aristotle when he was a boy.

Recall that it had long been speculated that Aristotle’s great comet of 372 BC might be the supermassive progenitor of the whole Kreutz family of the most brilliant sungrazing comets seen over the last two millennia, including the four ‘great’ comets seen in the late 19th century, two of which remain the brightest comets on record; and more recently, Ikeya-Seki – perhaps the greatest comet of the 20th century – which lit up the sky in 1965; and the brilliant Comet Lovejoy in 2011, among others. The light of that original comet, according to Aristotle, “stretched across the third of the sky in a great band.” Dr. Sekanina’s work now convincingly fixes the Comet of 372 BC indeed as that ‘great progenitor.’ His paper of last July reveals even more reconstructed details of Aristotle’s remarkable comet and its now ‘unquestionable’ status as the founding member of the Kreutz family [4].

You’ll probably also remember two game changers that contributed to Dr. Sekanina’s solution of the Kreutz puzzle. One was the discovery of whole new populations of dwarf sungrazers detected by the Solar and Heliospheric Observatory (SOHO) coronagraphs. These little mini-kreutzers helped fill in the gaps in sungrazer population charts. A revelation in theory came from images sent back by space-borne fly-bys of ‘contact binary’ objects like comet 67P/Churyumov-Gerasimenko and trans-Neptunian object Arrokoth. The refreshing notion that Aristotle’s comet was likely a twin-lobed monster meshed well with other aspects of Dr. Sekanina’s cometary thinking.

His simulations have revealed that, if the forces acting upon a contact binary are within very reasonable ranges of expectation, then it can surprisingly separate and fragment anywhere in its orbit, not just at perihelion passage as was the existing paradigm. Even slight tweaks to the modest vector forces impelling separation can have profound impacts on the orbital elements of the resulting fragments. This insight has opened the door for all sorts of new simulations to test.

Add to this a curious historical fact and clue to pinning down the orbital period of some fragments from Aristotle’s comet. Roman historian Ammianus Marcellinus wrote that in AD 363 'in broad daylight comets were seen'. If these daylight wonders were indeed the returning fragments of the magnificent comet seen by Aristotle, it suggests a period of about seven centuries or so for one of the main fragments of the (likely two-lobed) comet, which Sekanina calls Fragment I. After a second orbit, as described in my Dangerous Lives post, it arrived as the spectacular Great Comet of 1106 (X/1106 C1) likely the largest mass of Fragment I. On its third orbit it showed up as the Great March Comet of 1843 (C/1843 D1). (Keep an eye out for it in 2580 AD.)

And there was the mystery of Fragment II of the comet, which Dr. Sekanina has identified as the Chinese Comet of 1138. It passed perihelion about three decades after X/1106 C1. Its offspring included the historically brilliant comets: C/1882 R1 and C/1965 S1. And later, C/1970 K1 and likely C/2011 W3. How will C/2026 A1 (MAPS) fit into this far-flung family of wild and reckless comets?

Mapping MAPS on the Sungrazer family tree

According to Dr. Sekanina: “A major advantage of the contact-binary model is its pyramidal structure that organically explains any progression of populations derived from either of the two lobes as the corollary of its recurring (cascading) fragmentation.” We can see this by charting the paths of the sungrazers through history, tracing their cometary phylogeny to see how they are related, some closely, some more distantly. Onto this we can plot where MAPS fits in.

The x axis on the chart below shows years from Aristotle’s era through our own and beyond [5]. The radial marks on the right indicate every 10º of nodal longitude, (Ω in the comet tables of our Dangerous Lives post), with the x axis aligned at 0º. The circular arcs after AD 363 cut though each sungrazer’s perihelion year. The small red x’s represent fragmentation events. Solid diamonds show the dates of the sungrazer apparitions we’ve discussed. The lines are solid for the largest surviving masses of Aristotle’s Comet and the all-stars of the Kreutz show: the Great March Comet of 1843 and the Great September Comet of 1882.

Especially with White-Ortiz-Bolelli and Lovejoy striking out on their own paths, it is easy to appreciate the inadequacy of Marsden’s original two-population scheme we described in our Dangerous Lives article. We see how C/1963 R1 (Pereyra), too, looks like a duck out of water, not really in Population I, but rather superimposed on it. Dr. Sekanina put it in group Pe, as the only major member. Although too early to tell, it is quite possible that comet MAPS may give some company to Pereyra on the family tree, and be part of group Pe. It is shown as the red square by the number 2026. You can study the chart for yourself and visualize who is related to who, and how closely.

The long 1,672 year orbital period of MAPS points to a nominal time of previous perihelion of around 354 AD. Do you see where this argument is going? This is an almost  perfect fit with the Marcellinus’s record of the daylight comets seen in 363 A.D. According to Dr. Sekanina, there is “hard evidence” of tidal fragmentation of MAPS taking place at perihelion in 363 AD. This finding would make MAPS only a second-generation descendant of Aristotle’s comet, “comparable, for example, to the Great Comet of 1106, albeit on a reduced size scale.”

We should shortly learn as comet C/2026 A1 (MAPS) progresses along its orbital arc and more data is obtained, whether does in fact fit the bill as a close member of the Pe group, or whether it has other surprises in store for us. Of course, even with refined calculations along its orbital arc, as MAPS approaches the Sun it will assuredly experience out-gassing forces that may affect its orbital period. Its ultimate fate will depend on if and how it survives the fast crazy hairpin turn around the Sun at a scorching distance of about .00546 au. Will it simply vanish into the heat after sixteen centuries of travelling for this moment? Will it survive the passage but only as another disappointing headless wonder? Or (we hope) will it emerge into the northern hemisphere as an exceedingly glorious celestial beauty, another for the record books, as so many of its illustrious cousins have? We’ll soon see; the solar cauldron is tricky business for even the heartiest sungrazer!

Whatever happens, with each new wonderful discovery it’s again plain there will be more astonishing sungrazing comets to come and still more great new puzzles!

References

Top image shows Comet C/1963 R1 (Pereyra), courtesy C. F. Capen.

[1] https://www.douglasmacdougal.com/post/fast-times-and-dangerous-lives-of-sungrazer-comets.

[2] arXiv: 2602.17626v1 [astro-ph.EP] 19 Feb 2026. Unless otherwise noted, references and quotations attributed to Dr. Sekanina in this article are from this paper. Other references to his and his colleagues’ findings may be found in https://www.douglasmacdougal.com/post/fast-times-and-dangerous-lives-of-sungrazer-comets and the papers cited therein.

[3] S. Nakano, who has provided orbital data to the Central Bureau of Astronomical Telegrams, computed this value used by Z. Sekanina. There have actually been three sets of orbital parameters so far obtained. Dr. Sekanina believes Nakano’s data is the best because it is based on orbital arc of 52 days, and has a standard deviation better than 2%. (The two other computations are based on orbital arcs of only 20 days, and although close to Nakano’s, there is greater uncertainty in their orbital periods.)

[4] ArXiv:2507.15228v1 [astro-ph.EP] 21 Jul 2025.

[5] Not included on the graph is the great population of dwarf sungrazers detected by spacecraft, most especially the SOHO spacecraft, revealing up to nine separate groups of sungrazers, many not seen from Earth. Dr. Sekanina believes that those dwarfs may have be part of a swarm of fragments from X/1106 C1.