Calvin Keys, 3/12/01

Each phase of the night moon does about the same thing each lunar month. The new moon rises at dawn and sets at sunset. The first quarter rises at noon and sets at midnight. The full moon is always in the night sky and rises at sunset and sets at dawn. The last quarter rises at midnight and sets at noon. Like the sun, the moon travels east to west. It has a trajectory cycle of 18.61 years, ranging from just above the horizon to almost straight up in 9.305 years and traveling toward the horizon again, taking 9.305 years to complete the second half of the cycle. From new moon to new moon is called a Synodic month. I calculated the average Synodic month to be 29 days, 12 hours and 15 minutes, using the exact rotation of the earth that is 24 hours, 1 minute and 1.545205 seconds per day. This calculates to 2,551,485 seconds in the average Synodic month. 2,551,485 seconds divided into 6,942,677,200 seconds, (220 years at 31,558,464 seconds per year) equals 2721 lunar orbits with 86,515 seconds left over. An exact day is 86,461.545 seconds; therefore 86515 seconds is 1 day and 53 seconds. The moon was waning or just one day passed it's 2721st lunar orbit on August 15, 1780, counting backwards from the full moon on August 15, 2000.


In summary, the moon was full on August 14, 1780, at 9:48 PM. It was waning at 99% full and 100% illuminated as the armies left their camps at 10:00 PM on August 15th, 1780. Moonrise on the 15th was at 7:53 PM in the East at 107.4 degrees. At 10:00 PM the moon was at 127.6 degrees southeast and 22.1 degrees above the horizon. By 1:25 AM on August 16th, 1780 the moon was at its highest point in the sky of the evening, at 41.5 degrees above the horizon and south at 180 degrees. When the armies met at 2:30am on August 16th, the moon was 39.2 degrees above the horizon and southwest at 201.3 degrees. This places the moon behind the British Army that may have given them some advantage in the night battle.


Some of revolutionary war accounts state that it was a hot night and partly cloudy as the Armies met under a tall canopy of widely spaced pines. The road was wide with many parallel paths in the deep white sand and no doubt, the sand gleamed under the full moon as the armies met, eight tenths of a mile north of Gum Swamp Creek. The night battle covered three-tenths of mile farther north by the time both sides pulled back. The British Army lay on the ground at one mile north of Gum Swamp. The American Army was six hundred yards north of the British.

Moon research resources: Many Moons by Diana Brueton and The Astronomical Applications Dept., U.S. Naval Observatory, Washington, DC

Source: CBB cd