Meton of Athens
Meton of Athens was a
Greek mathematician,
astronomer, and
engineer who lived in
Athens in the 5th century
BCE. He is best known for the 19-year
Metonic cycle which he introduced into the
lunisolar Attic calendar as a method of calculating dates.
A year of 12
synodic or
lunar months is 354 days on average, 11 days short of the 365.25 day
solar year. The Athenians appear not to have had a regular means of
intercalating a 13th month; instead, the question of when to add a month was decided by an official. Meton introduced a formula for intercalation. It was his observation that a period of 19
solar years (6,940 days) is almost exactly 235 lunar months, with an error of only 2 hours between 19 years and 235 months. 7 of the 19 years would have an intercalated month. This cycle can be used to predict
eclipses, forms the basis of the Greek and
Jewish calendars, and is used to determine the date for
Easter each year. In Antiquity the Metonic cycle was sometimes called the
Great year. Among astronomers, it was superseded in the following century when
Callippus developed the
Callippic cycle.
It is surprising that
Homer knew about the cycle some centuries before Meton, and used it in the
Odyssey. Homer makes
Odysseus leave
Ithaca, and then return and secretly meet
Penelope at just the exact moment one cycle occurs
[ Gilbert Murray. The Rise of the Greek Epic. Oxford, (1907)] [ Joseph Campbell. The Masks of God: Occidental Mythology, vol III, (1964)].
[ J.F. del Giorgio. The Oldest Europeans. A.J. Place (2006)].
Meton was one of the first
Greek astronomers to make accurate astronomical observations. Working with
Euctemon, he observed the
summer solstice on June 27, 432 BCE.
About 430 BCE, he determined the length of the
tropical year to be about 365 days, 6 hrs and 19 mins, which is 31 minutes longer than the modern value. It gives exactly 6,940 days to one 19-year cycle.
Meton appears briefly as a character in
Aristophanes' play
The Birds. He comes onstage carrying
surveying instruments and is described as a
geometer.
None of his works survive.
* Toomer, G. J. "Meton."
Dictionary of Scientific Biography 9:337-40.
*
Meton of Athens*
Greek Astronomy
