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October 2006 Feature: Shine On Harvest Moon!

Customarily, the Full Moon coming closest to the time of the autumnal equinox inherits the mantle of Harvest Moon. In 2006, the honor is bestowed upon the Oct. 7 Full Moon, which comes to pass at 3:13 a.m. Universal Time (11:13 p.m. Oct. 6 Eastern Daylight Time). However, this is some two weeks after the Sept. 23 equinox, about the latest date possible for a Harvest Moon. With the equinox falling virtually halfway between the Sept. 7 and Oct. 7 Full Moons, we could almost say we have co-stars: two Harvest Moons in the same year. Any Full Moon taking place within a few weeks of the autumnal equinox displays characteristics associated with a Harvest Moon.

The Full Harvest Moon -- like any Full Moon -- rises around sunset, shines from dusk till dawn, and sets around sunrise. Before the advent of artificial lighting, our ancestors no doubt appreciated the fact that the Full Moon shines all night long! Our ancestors noted, moveover, that near the autumnal equinox the Moon continues to shine from dusk till dawn for several days after the Full Moon -- something that does not happen at other times of the year. With the daylight hours in autumn quickly waning day by day, such a boon in moonlight must have been viewed as a gift of providence!

On the average, the Moon rises about 50 minutes later every night. This lag time between successive moonrises, however, is reduced to a bare minimum at the time of the Full Harvest Moon. And the farther north you live from the equator, the greater the Harvest Moon effect. For example, at 45 degrees N. latitude, the Moon rises some 21 to 22 minutes later on the night after the Full Harvest Moon; whereas at 60 degrees N. latitude, moonrise happens at virtually the same time for several days in a row.

The 24 hour and 50 minute lag period between successive moonrises presumes the Moon rises at or near the same place on the horizon. But for several days after the Full Harvest Moon, the moon continues to rise farther north along the horizon. In our Northern Hemsiphere, a Moon that rises north of where it rose the night before rises sooner than the average 50 minutes later per day.

This year, in fact, the Moon is at a peak in its 18.6 year-cycle, whereby each month the Moon swings from about 28.5 degrees north to 28.5 degrees south of the Earth's equator. This peak accentuates the Harvest Moon effect. But in 2015, the Moon's monthly north-to-south wanderings are tied to its shortest tether in this 18.6-year cycle, only swinging from about 18.5 degrees north to 18.5 degrees south of the equator. This minimal variation in the Moon's monthly north-to-south peregrinations also minimizes the impact of the Harvest Moon.

Harvest Moon of October 2006

CityMoon's Rising TimeMoon's Rising Position
Seattle, Washington6:24 p.m. Oct. 6 9 degrees north of due east
6:43 p.m. Oct. 720 degrees north of due east
7:06 p.m. Oct. 829 degrees north of due east
Anchorage, Alaska6:55 p.m. Oct. 614 degrees north of due east
6:52 p.m. Oct. 729 degrees north of due east
6:48 p.m. Oct. 844 degrees north of due east

Harvest Moon of September 2015

CityMoon's Rising TimeMoon's Rising Position
Seattle, Washington6:54 p.m. Sept. 27 2 degrees north of due east
7:28 p.m. Sept. 28 9 degrees north of due east
8:04 p.m. Sept. 2915 degrees north of due east
Anchorage, Alaska7:42 p.m. Sept. 27 3 degrees north of due east
8:02 p.m. Sept. 2813 degrees north of due east
8:25 p.m. Sept. 2922 degrees north of due east

copyright 2006 by Bruce McClure

September 2006 Feature * November 2006 Feature

Custom Printable Monthly Calendar: Sunrise/Sunset & Moonrise/Moonset

Past Harvest Moon Features:
Sept. 2005 Harvest Moon
Sept. 2003 Harvest Moon
Sept. 2002 Harvest Moon