A historian from the University of Leicester believes that Eilmer of Malmesbury may have observed two distinct comets: one in 1018 and another in 1066.
In the early 11th century, a young Benedictine monk named Eilmer leaped from the 150-foot tower of his abbey in the small English town of Malmesbury, equipped with crude wings he had constructed from willow wood and fabric. Eilmer managed to glide approximately 600 feet, clearing the city wall before crashing in a small valley near the River Avon. The fall broke both his legs, leaving him crippled. Malmesbury Abbey still features a stained-glass window commemorating Brother Eilmer.
This famous medieval aviation experiment is known to us through the 12th-century historian William of Malmesbury, who wrote about it around 1125, though he did not provide future historians with a precise date for the event. However, William does recount another significant moment in Eilmer’s life when the monk was “advanced in years”: Eilmer witnessed Halley’s Comet in 1066, remarking, “It is long since I saw you.” Some historians have interpreted this to mean that Eilmer had seen Halley’s Comet during an earlier appearance in 989, when he would have been a young child.
Assuming Eilmer was at least 5 years old in 989, he would have been born no later than 984. This would make Eilmer in his 80s by 1066, with his flight attempt—which occurred when he was “in his first youth”—likely taking place between 1000 and 1010. However, this estimate relies on numerous assumptions, according to James Aitcheson of the University of Leicester. In a paper published in the journal *Notes and Queries*, he argues that Eilmer may have seen a different comet entirely during his youth—the comet of 1018. If this were the case, Eilmer would have been born much later, and his flight would have occurred between the 1020s and 1040s.
The comet of 1018 would have been visible in the British Isles for approximately two weeks in the autumn, per Aitcheson. Eilmer may have simply assumed it was the same comet he observed in 1066 with Halley’s Comet, which left him “crouching in terror at the gleaming star.” Aitcheson suggests that Eilmer could have been born in the early 1010s, making him over 50 in 1066, which is still technically consistent with William of Malmesbury’s description of Eilmer as advanced in years.
This would also challenge recent speculation that Eilmer understood the periodicity of Halley’s Comet centuries before the late 17th-century astronomer Edmond Halley. So should it really be called Eilmer’s Comet? Aitcheson thinks not. He acknowledges that Eilmer could have had access to historical records of comet sightings in Britain and Europe, and thus could have identified the pattern of its cycle among other records of comet appearances.
However, the only record we have of Eilmer comes from William of Malmesbury, who does not mention whether Eilmer was an amateur astronomer. “Indeed, it is not clear that sky-watchers in the Early Middle Ages were able to tell one comet apart from another,” Aitcheson writes in his paper. A later birth date for Eilmer also makes it just possible that the monk lived long enough (to age 90) to meet William in person and “directly passed on the story of his pioneering feats of aviation.”
*Notes and Queries*, 2026. DOI: 10.1093/notesj/gjag066 (About DOIs).