What Aristotle Thought About Halley’s Comet

Hailey-Comet Halley's comet we have discovered recently was spotted by the ancient Greeks, based on accounts by ancient authors.

In his work Meteorology, Aristotle wrote about the event about a century after it occurred. He said that around the same time the meteorite fell, "a comet was visible in the west."  Aristotle, a student of Plato and teacher of Alexander the Great, concluded that comets were some kind of emission from Earth that rose into the sky. The heavens, he maintained, were perfect and orderly; a phenomenon as unexpected and erratic as a comet surely could not be part of the celestial vault.

According to ancient writers, a large meteorite smacked into northern Greece between 466 BC and 467 BC. The writers also described a comet in the sky at the time the meteorite fell to Earth, but this detail has received little attention, say the researchers. Halley's Comet  would have been visible for about 80 days in 466 BC, researchers write in the Journal of Cosmology. New Scientist magazine writes that, until now, the earliest probable sighting of the comet was an orbit in 240BC, an event recorded by Chinese astronomers.If the new findings are confirmed, the researchers will have pushed back the date of the first observation of Comet Halley by 226 years.

The space rock fell during daylight hours and was about the size of "a wagon load", according to ancient sources. The object, described as having a "burnt colour", became a tourist attraction for more than 500 years.

Astronomer Eric Hintz and philosopher Daniel Graham, both of Brigham Young University in Provo, Utah, reconstructed the likely path of Halley's comet and calculated that Halley's comet could have been visible for about 80 days between early June and late August in 466BC – depending on atmospheric conditions and the darkness of the sky.

"It's tough going back that far in time. It's not like an eclipse, which is really predictable," co-author Eric Hintz, from Brigham Young University in Provo, Utah, told BBC News.

In the 11th Century, Halley's Comet was depicted on the Bayeux Tapestry. The reconstruction of the comet's path agrees with the ancient reports, which say the comet was visible for about 75 days.

The researchers point out that while the Chinese and Babylonians kept meticulous records of heavenly phenomena for centuries, the ancient Greeks did not. The Greek accounts, howevee, do provide important information, say Graham and Hintz, such as the comet's period of visibility from Earth.

Asked whether it was possible that the meteorite fall and the pass by Halley's Comet could be linked, Dr Hintz was doubtful. "Tt would be really neat if they were connected – if it was a piece of Halley's that fell. My feeling is that it was just a really cool coincidence," said Dr Hintz.

The researchers say that there remains the possibility that other ancient sightings of comets could be uncovered from Chinese and Babylonian records.

Perhaps, someday, we discover a cave painting depicting a starling cosmic events. What an amazing discovery that would be!

Casey Kazan via BBC News.

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