Around the year 1005, an English Benedictine monk climbed the tallest tower of Malmesbury Abbey, strapped a pair of wooden-and-cloth wings to his hands and feet, took a deep breath, and jumped. His name was Eilmer, and against all odds, it actually worked: he glided for more than 200 metres before crashing to the ground. The strange part isn’t just that a medieval monk tried to fly six centuries before Leonardo da Vinci ever sketched a flying machine. The strange part is that, decades later, that same man was behind another discovery almost as remarkable: he was one of the first people in history to figure out that comets come back.
The jump that broke both his legs (and left him lame for life)
Everything we know about Eilmer comes from a single chronicler: William of Malmesbury, the medieval historian who wrote about him around 1125 in his work Gesta regum Anglorum, drawing on accounts from people who had known Eilmer in his old age. According to that record, the monk launched himself from the top of the abbey tower, caught the wind, and managed to glide “more than a furlong” — roughly 201 metres — before losing control and falling.
The landing was not gentle: he broke both legs and walked with a limp for the rest of his life. The best part of the story is his own explanation for the crash, also recorded by the chronicler. Eilmer was convinced he had failed for one very specific reason — he’d forgotten to fit himself with a tail, like a bird. Not the lift, not the technique of the jump itself: no tail. Two hundred metres gliding on homemade wings in the 11th century, and his big engineering takeaway was that.
The same monk, another discovery ahead of its time
That could have been the end of the story — a reckless friar with bad luck. But Eilmer resurfaces more than sixty years later, now an old man, watching the sky in 1066 as a bright comet swept across England just before the Battle of Hastings (the very same comet later immortalized in the Bayeux Tapestry). According to William of Malmesbury’s account, Eilmer didn’t just react with fear like everyone else — he recognized the comet. He’d seen it before, back in 989, when he was young, and realized it was the same object returning to the sky.
A 2026 study by astrophysicist Simon Portegies Zwart, of Leiden University, has taken a closer look at that claim. The gap between the two sightings described in the chronicle — 989 and 1066 — is 77 years, almost exactly matching Halley’s Comet’s real orbital period of about 76 years. In other words, Eilmer didn’t just spot the comet twice: he reached the correct conclusion that comets aren’t one-off apparitions but objects that return on a regular cycle. That’s the very same reasoning that would, nearly 700 years later, earn Edmond Halley his place in history when he predicted in 1705 that the comet now bearing his name would come back.
So why isn’t it called “Eilmer’s Comet”?
Simply because Halley did something Eilmer couldn’t: he calculated the comet’s orbit using Newtonian mathematics and published a testable prediction, one that came true in 1758, sixteen years after his death. Eilmer had the right intuition, armed only with the tools of a medieval monastery — observation, memory, and common sense — but he lacked the physics to prove it. Even so, the researchers behind the study argue that, historically speaking, it’s worth remembering that the idea of returning comets didn’t start with Halley.
In the end, Eilmer’s life sums up what it means to be ahead of your time pretty well: getting two enormous ideas right — that you can fly with the right wings, and that a comet can come back for a second visit — and being remembered mostly for the broken legs and the tail he forgot.
You can read more about this research at Universe Today.