Clouds may have obscured it, but last night's full moon was the nearest to Sunday's fall equinox, so that makes it the Harvest Moon. A nearly forgotten relic of our agricultural past, the Harvest Moon provided vital illumination all night long for farmers rushing to get their crops in before winter. To the Sioux, it was the Dying Grass Moon, Guy Ottewell's Astronomical Calendar tells us. In China, the autumn moon ties lovers with invisible thread. And I thought those were cobwebs.