2500 anniversary: battle of Marathon

Sat. August 20, 2011
Categories: anniversary, antiquities, astronomy, Greece, Herodotus, Sparta

According to Sky & Telescope magazine, the 2500 anniversary of the battle of Marathon was on August 12, 2011, and not, as many other sources had reported, in 2010.

Herodotus wrote that the Spartan army awaited the full moon before marching to Martahon to assist the Athenians in their effort to repel the Persian invasion.

Using these full-Moon clues, most modern books about the battle adopt the calculations of scholars who studied the Athenian calendar, identified this full Moon as falling on September 9, 490 BC, and placed the Battle of Marathon on September 12, 490 BC.

In a past article (“The Moon and the Marathon” in Sky & Telescope’s August 2004 issue), we pointed out that the calculation should be done in the Spartan calendar. Our suggested chronology favored the full Moon of August 10, 490 BC, and placed the Battle of Marathon on August 12, 490 BC.

Apparently, most websites then miscalculated the 2,500 anniversary date to 2010:

In the astronomical year numbering system, advocated by the French astronomer Jacques Cassini, the year preceding 1 AD is called the year 0, and years before that are assigned negative numbers.

The Battle of Marathon therefore occurred in the astronomical year –489 (the historical year 490 BC), and the correct arithmetic is –489 + 2500 = 2011.