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November 2002: Veterans Day First Quarter Moon

The first quarter moon this month falls on November 11th, or Veterans Day. At nightfall on this date, the Moon bedecks the southern sky, with the western half of the Moon fully basking in sunshine, while the eastern half is veiled by the darkness of night.

Why a Moon that's half illuminated should be called a "quarter moon" is a mystery, but there are a few explanations for it. Most commonly, it's said that the Moon in its monthly pilgrimage from new moon to new moon completes one quarter of its journey at the first quarter phase. Another explanation has it that the Moon is always half lit and half in darkness, and that at quarter moon one half of the lit side faces Earth wheras the other half of the lit portion lies on the back side of the Moon unseen. In other words, a half of a half lit Moon equals a quarter-lit moon.

That complication aside, the first quarter moon shines in the constellation Capricorn, the seagoat, and stands above the globular star cluster M 30. The cluster, however, eludes naked eye visibility, and you need a telescope (or good binoculars) to see it.

Though the lunar month usually refers to the duration of time between successive new moons, it can refer to successive returns of any choosen phase (such as first quarter moon to first quarter moon). The lunar month is somewhat variable in length but averages just over 29.5 days. Twelve lunar months make a lunar year of about 354 days (12 x 29.5 = 354), which is some eleven days shorter than the 365 day seasonal calendar that we use today.

Because of this difference between the lunar year and the seasonal year, the quarter moon one lunar year from now (2003) won't fall on Veterans Day, but on Halloween. It's inevitable, however, that the first quarter moon and Veterans Day will realign once again. Lunar and seasonal cycles reconcile every nineteen years, with 235 lunar months equaling nineteen seasonal years to the day. (See Metonic Cycle.) In the years 2021 and 2040, the first quarter moon not only falls on Veterans Day but also returns to virtually the same place among the stars - standing, once again, near M 30 in Capricorn.

Copyright autumn 2002
by Bruce McClure

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