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Texas State astronomers unravel Marathon mystery

Date released: 07/19/04

SAN MARCOS— On Aug. 29, a field of runners at the 2004 Summer Olympic Games in Athens, Greece, will retrace one of the most famous runs in history. But it is a team of researchers half a world away in Texas that shed new light on the origins of the legendary race. In "The Moon and the Marathon," published in the September 2004 issue of Sky & Telescope magazine, Donald W. Olson, a physics and astronomy professor at Texas State University, and his San Marcos colleagues Russell L. Doescher and Marilynn S. Olson present astronomical evidence to show the commonly accepted date of the famous battle and ensuing run may need to be reconsidered.

The legend was born in 490 B.C., when a lone runner raced some 26 miles from the battlefield to Athens to bring word of the Greeks' victory over the Persians at Marathon, and to warn the city of an impending invasion from the sea by the Persian fleet. His mission accomplished, the runner collapsed and died. This melodramatic death has proved problematic for historians over the centuries: Why would an experienced, long-distance runner collapse when thousands of amateur runners successfully compete in marathons worldwide? The answer lies in the phases of the moon.

"The Greek historian Herodotus provides precise descriptions of the phase of the moon near the time of the Battle of Marathon," said Donald Olson. "These are the key to dating the battle and the Marathon run using astronomy." When the Athenians first learned of the Persian army's landing at Marathon, city leaders dispatched a messenger to Sparta, 150 miles away, to plead for military aid. The Spartans promised to help, but explained that because of a religious festival their army could not march before the next full moon--six days away. Judging that the festival was the Karneia, the 19th-century German scholar August Buekh carried out a series of astronomical calculations to determine the date of the Karneian full moon, and determined that the Battle of Marathon took place on Sept. 12. Buekh relied on a reference from Greek scholar Plutarch that equated the Spartan month of Karneios with Metageitnion, the second month of the Athenian year.

"We realized that the previous method of dating, using the Athenian calendar, had a serious flaw," Olson said. "The Karneia was a Spartan festival, so the analysis should be done in the Spartan calendar." Although the Spartan and Athenian calendars were similar in that they were both lunisolar--following the lunar cycle, but making adjustments to stay in step with the solar year--they were not identical. The Athenian year began with the first new moon following the summer solstice, but the Spartan year apparently began with the first new moon after the fall equinox. Further, in 491-490 B.C., 10 new moons occurred between the fall equinox and summer solstice instead of the normal nine, resulting in the Spartan calendar's running a month ahead of the Athenian. If the Texas State researchers are correct, the Battle of Marathon actually took place on Aug. 12, 490 B.C.

Previous writers have noted that Athens' average maximum temperature during September is approximately 83 degrees Fahrenheit, but moving the Marathon date back just one month has a dramatic effect. The average August afternoon temperatures along the marathon route range from 88 to 91 degrees, with temperatures as high as 102 possible near Athens. The astronomical calculation therefore suggests an explanation for the death of the runner: such conditions could lead to heat exhaustion and heat stroke in even a trained athlete.