According to ancient writers, a large meteorite smacked into northern Greece between 466BC and 467BC.
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.
Comet Halley would have been visible for about 80 days in 466BC, researchers write in the Journal of Cosmology.
New Scientist magazine reports 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.