Halley's Comet May Be Misnamed, 11th-Century Monk First to Spot It

New Research Challenges Centuries-Old Naming Convention

Groundbreaking research by a Dutch astronomer and a British historian suggests that Halley's Comet, one of the most famous celestial objects in human history, may have been misnamed for centuries. According to their findings, an 11th-century English monk named Eilmer of Malmesbury recognized the comet's 76-year return cycle long before Edmund Halley's 17th-century calculations.

The Five-Year Investigation

Astronomer Simon Portegies Zwart from Leiden University and historian Michael Lewis spent five years examining medieval manuscripts and historical records. Their research began when Portegies Zwart visited the Bayeux Tapestry in France, where Halley's Comet is prominently depicted above the scene of King Harold's coronation in 1066.

'You have to imagine that the sky looked completely different in the 11th century than it does now,' Portegies Zwart explained. 'Only the brightest stars are visible today with all the street lighting. But back then, there was no electric light and you could see the entire starry sky every night. When such a comet suddenly passed by, it had an enormous impact. And often they attached meaning to it.'

Eilmer's Remarkable Recognition

The researchers discovered that Eilmer of Malmesbury, also known as Aethelmaer, wrote in 1066 that he was seeing the comet for the second time. Historical analysis suggests he likely first saw it as a young boy in 989, making him about 76 years old when it returned.

'He must have been a little boy when he saw Halley's Comet for the first time, and 76 years later he recognized it and remembered that all kinds of calamities had occurred that first time: there was famine, a king died, Vikings invaded England,' Portegies Zwart noted. 'He therefore warned that something similar could happen again now.'

What remains mysterious is how Eilmer knew it was the same comet. 'That's a mystery,' the astronomer admitted. 'Some comets are very recognizable, they have two tails for example. What exactly it was in this case, we don't know. But I remember how I saw Halley myself from the schoolyard in 1986. It's an impressive experience every 76 years.'

Historical Context and Medieval 'Fake News'

The research reveals fascinating insights into medieval astronomy and record-keeping. Monks meticulously noted the passage of comets, often linking them to significant events. 'Often certain events were linked to them, such as the death of a king,' Portegies Zwart explained.

This practice even led to an early form of misinformation. 'Because sometimes a cardinal would die, and then they would also give him a comet in the chronicles. Even though no comet had been visible in that year at all.'

The researchers also examined the Bayeux Tapestry's depiction of the comet, noting that its placement above Harold's January 1066 coronation is historically inaccurate since the comet wasn't visible until April. This appears to be political propaganda, retrospectively linking the comet to Harold's doomed reign to support William the Conqueror's narrative.

The Naming Debate

Portegies Zwart and Lewis published their findings in the academic book Dorestad and Everything After. Ports, townscapes & travellers in Europe, 800-1100, which includes a plea to rename Halley's Comet. However, the astronomer acknowledges the practical challenges.

'That's not very serious,' he admitted. 'The name Halley is so ingrained that you can hardly change it, and besides: Halley was the first who not only connected the observations with each other, but also managed to predict them. So that was still an important step in astronomy. And he has of course done much more.'

Edmund Halley, who lived from 1656 to 1742, used Newton's laws of motion to predict the comet's return in 1758, though he didn't live to see it. His work demonstrated that comets orbit the sun and can return periodically.

Scientific Significance

While the naming debate may be somewhat academic, the research highlights important aspects of astronomical history. Halley's Comet, officially designated 1P/Halley, is the only known short-period comet consistently visible to the naked eye from Earth, appearing every 72-80 years. It last appeared in 1986 and is next predicted to return in mid-2061.

The comet has been observed since at least 240 BC, with Chinese, Babylonian, and medieval European records all documenting its appearances. The 1986 apparition marked the first time a comet was observed in detail by spacecraft, including ESA's Giotto mission, which confirmed the 'dirty snowball' model of comet composition.

Portegies Zwart, a professor of numerical star dynamics at Leiden University, specializes in computational astrophysics and high-performance computing simulations. His collaboration with historian Michael Lewis represents an interdisciplinary approach to understanding both the scientific and cultural significance of celestial phenomena throughout history.

For more information about Halley's Comet, visit Wikipedia. Details about Simon Portegies Zwart's research can be found on the Leiden University website.