In 1066, an elderly Benedictine monk stood in the grounds of Malmesbury Abbey in southwestern England and watched a bright, tailed star climb across the spring sky. According to the medieval chronicler William of Malmesbury, the monk, known as Eilmer, was not frightened. He had seen this object before. Decades earlier, as a young man in 989, he had watched the same blazing visitor arc overhead. Now, in the final years of his life, he reportedly declared that the comet had returned and that it brought ruin with it.
That recognition, if accurate, would mean Eilmer grasped the periodic nature of the object we now call 1P/Halley more than six centuries before Edmond Halley published the mathematical proof that earned the comet his name. A preprint posted in 2025 by researchers Michael Lewis and Simon Portegies Zwart revisits the evidence and argues that the monk deserves far more credit than history has given him.
The monk who also tried to fly
Eilmer of Malmesbury is not an obscure figure to medievalists. He is perhaps best known for strapping wings to his arms and leaping from the abbey tower around 1010, gliding roughly 200 meters before crash-landing and breaking both legs. William of Malmesbury recorded that episode, too, in his 12th-century chronicle Gesta Regum Anglorum (“Deeds of the English Kings”), portraying Eilmer as a man willing to test ideas with his own body. The glider story has been cited in histories of early aviation for over a century.
The comet story appears in the same chronicle. William wrote that when the comet blazed over England in the spring of 1066, Eilmer addressed it directly, saying he had seen it long ago and that it foretold the destruction of his country. Within months, Harold Godwinson was dead at the Battle of Hastings and Norman rule had begun. A NASA historical note ties the comet’s 1066 appearance to the political upheaval of that year, and the Bayeux Tapestry, the famous embroidered chronicle of the Norman Conquest, depicts the comet in its panels as courtiers point skyward beneath the Latin inscription ISTI MIRANT STELLA (“These men wonder at the star”).
The gap between Eilmer’s two sightings, 989 and 1066, spans 77 years. The comet’s known orbital period is approximately 75 to 76 years, with slight variation caused by gravitational perturbations from the giant planets. The match is close enough to have intrigued historians of science for decades.
What Halley actually did
Edmond Halley’s claim to the comet rests on a specific intellectual achievement. In his 1705 treatise A Synopsis of the Astronomy of Comets, he used Isaac Newton’s gravitational theory to compute the orbits of 24 comets observed between 1337 and 1698. He noticed that the comets of 1531, 1607, and 1682 shared strikingly similar orbital elements and concluded they were a single object on a roughly 76-year loop. He then predicted it would return around 1758. A digital facsimile of the treatise held by the Smithsonian Libraries preserves his original reasoning.
Halley died in 1742, but the comet reappeared on schedule in late 1758, spotted first by the German farmer and amateur astronomer Johann Georg Palitzsch on Christmas night. The successful prediction transformed comets from unpredictable omens into calculable members of the solar system and secured Halley’s name in perpetuity.
By the conventions that govern comet naming today, Halley’s designation is unassailable. The International Astronomical Union credits the astronomer who first determines an orbit or predicts a return, not the earliest person to notice a pattern. Eilmer made no calculation, left no written model, and offered no forecast of a future apparition.
The case the preprint makes
Lewis and Portegies Zwart, whose preprint is titled “The significance of Halley’s Comet in the Bayeux Tapestry,” do not argue that Eilmer should replace Halley in official catalogues. Their point is historical and philosophical: they contend that medieval observers were more attuned to cometary recurrence than standard histories of science typically acknowledge.
The researchers cross-reference the Bayeux Tapestry’s comet panels with written accounts from English, Chinese, and Middle Eastern chronicles around 1066, treating the Tapestry not merely as political propaganda but as a visual document encoding real astronomical observation. They then place Eilmer’s reported recognition alongside the broader record of the comet’s earlier apparitions, arguing that his remark, as transmitted by William of Malmesbury, represents the earliest known instance of a named individual claiming to have witnessed the same comet twice and identifying it as the same object.
That framing raises a pointed question: if recognizing a comet’s return is the intellectual breakthrough, does the credit belong to the person who first experienced that recognition, or to the person who first proved it with mathematics?
Why the evidence is still contested
The most significant limitation is that no text written by Eilmer himself has survived. Everything known about his observations comes through William of Malmesbury, who composed Gesta Regum Anglorum roughly 60 to 70 years after the 1066 apparition. William was a meticulous historian by medieval standards, with access to the Malmesbury Abbey library and its oral traditions, but his account is still a secondary source separated from the events by decades. No monastic manuscripts from the abbey containing Eilmer’s own observations have been found or digitized.
There is also the question of what Eilmer’s recognition actually meant within his own intellectual framework. Medieval cosmology, shaped by Aristotelian physics and Christian theology, classified comets as atmospheric phenomena or divine signs, not as icy bodies tracing elongated solar orbits. Even if Eilmer genuinely recognized the same luminous object from his youth, he would not have understood its return in terms of gravitational mechanics or orbital periods. His insight, if real, was experiential rather than theoretical.
The reliability of memory across a 77-year span adds another layer of uncertainty. If Eilmer was a young man in 989, he would have been in his 90s by 1066, an extraordinary age for the period. William does not specify how he learned Eilmer’s story, whether through the monk’s own writings, oral tradition within the abbey, or a chain of retellings. Each link in that chain introduces the possibility of embellishment, especially given the retrospective temptation to frame the comet as a portent of the Norman invasion.
The preprint itself, as of June 2026, has not yet passed formal peer review. It is hosted on arXiv, a preprint server operated through Cornell University where papers are posted before journal publication. The arguments it advances are analytical, drawing on existing primary sources rather than newly discovered artifacts. Historians may offer counterarguments, and the scholarly conversation is still in its early stages.
A longer history than either man
It is worth noting that neither Eilmer nor Halley was the first human to record the comet. Chinese astronomers documented an apparition in 240 BCE, and systematic Chinese records track many of its subsequent returns. The comet’s 164 BCE and 87 BCE appearances are preserved in Babylonian clay tablets. By the time Eilmer watched it from Malmesbury in 989, the object had been observed and recorded across multiple civilizations for over a millennium.
What makes Eilmer’s case distinctive is not priority of observation but the personal continuity of his experience. He is, if William’s account is accurate, the earliest named individual known to have seen the comet on two separate passes and to have said so. That is a different kind of claim than Halley’s, and a different kind than the anonymous Chinese court astronomers who logged each apparition without linking them across centuries.
Whether that personal recognition rises to the level of scientific discovery depends on where one draws the line between intuition and proof. Halley drew it with a quill, a set of orbital calculations, and a prediction that outlived him. Eilmer, if the chronicle is faithful, drew it with his memory and a single, startled declaration to his fellow monks. Nearly a thousand years later, the question of who truly understood the comet first remains open, and the answer may say as much about how we define understanding as it does about the comet itself.
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*This article was researched with the help of AI, with human editors creating the final content.
