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Awash in the Moon’s Glow

The Harvest Moon brightens more than one night

The night skies are alight with the glow of the Harvest Moon, which is technically full on the 12th but appears to shine from dusk to dawn over several nights. Every full moon rises around the time of sunset and sets the next morning around sunrise, but only for one day. However, the Harvest Moon, the full moon closest to autumnal equinox, which falls on September 21, is different.
    This time of year, the moon travels at its lowest along the ecliptic — the path of the sun, moon and planets — creating a shallow angle with the horizon. This narrow angle makes for a shorter path across our skies, which creates the effect of the Harvest Moon rising in near the same place and at near the same time night by night.
    Normally the moon rises at least 50 minutes later with each passing night. But with the narrow angle of the ecliptic in relation to our own horizon, the Harvest Moon hereabouts rises only 25 minutes later each night. The farther north you view the Harvest Moon, the tighter the angle and the shorter the gap between successive moon rises. In Northern Europe and Canada, the difference is only 10 or 15 minutes a night, while near the Arctic Circle, the moon rises at nearly the same time for days on end.
    Before electricity and mechanized agriculture, farmers relied on these moon-washed nights to offset the shrinking hours of daylight in order to complete the harvest.
    The sun sets around 7:20, revealing Saturn low in the west for an hour before it too sets. Jupiter rises a few hours after sunset and is high in the southwest with sunrise, after 6:40. Mars rises after 2am and is high in the east come dawn. Less than an hour before dawn, Mercury creeps into view. At magnitude –1, it’s currently brighter than anything but the sun and moon, more than twice as bright as Regulus just a few degrees higher