Meton of Athens
Meton of Athens (Greek: Μέτων ὁ Ἀθηναῖος; gen.: Μέτωνος) was a Greek mathematician, astronomer, geometer, and engineer who lived in Athens in the 5th century BC. He is best known for calculations involving the eponymous 19-year Metonic cycle which he introduced in 432 BC into the lunisolar Attic calendar.
The metonic calendar incorporates knowledge that 19 solar years and 235 lunar months are very near equal, thus lunar periods repeat on the same day of the year as 19 years previous. This system was based on calculations made by Meton using his own observations of the summer solstice in 432 BC, and an observation made by Aristarchus 152 years later. Meton's observations were made in collaboration with Euctemon about whom nothing else is known. The Greek astronomer Callippus continued the work of Meton, proposing what is now termed the Callippic cycle. The Callippic cycle is 76 years long, four Metonic cycles. Callippus refined the Metonic cycle, deducting one day every four Metonic after 940 synodic lunar periods to synchronize the lunar calendar with the year.
The world's oldest known astronomical calculator, the Antikythera Mechanism (2nd century BC), performs calculations based on both the Metonic, and Callipic calendar cycles, with separate dials for each.
The foundations of Meton's observatory in Athens are still visible just behind the podium of the Pnyx, the ancient parliament. Meton found the dates of equinoxes and solstices by observing sunrise from his observatory. The bisectrice[clarification needed] of the observatory lies in an easterly direction, between the Acropolis and the Lycabetus hill.
What little is known of Meton come through ancient historians. According to Ptolemy, a stella or table erected in Athens contained a record of Meton's observations, and a description of the Metonic cycle. None of Meton's works survive.
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