This Sunday, March 16, the Northern Hemisphere will experience its last full moon of a very hard winter. Traditional names for this moon include Lenten Moon, Crow Moon, Sugar Moon, Sap Moon, Worm Moon, and Death Moon, reminding us how closely humans have linked the lunar cycles with the cycles of life here on Earth.
Of course, the moon itself has nothing to do with the growing season; it's the steeper angular tilt of the Sun that warms our upper half of the Earth. And the longer days.
4 days after the full moon, on March 20, the Sun will touch our celestial equator – appearing directly overhead at the equator at local noon – an event that heralds the first day of Spring.
But the moon's 28-day cycle has always been a easy way to measure time's progression, especially in the centuries before standardized calendars became wide-spread. To cultures dependent on the land, the fact that sap was rising in the maples or the ground had warmed enough for worms to emerge would have been as important as the Moon's phase. This sort interdependence between the human and natural world is echoed in the common names for many plants. In America, we still call our species of Amalanchier "serviceberry," since its early spring blossoming signaled that the ground had thawed enough to perform funerals delayed by winter.
The actual time the moon reaches its full phase on Sunday is 1:06 pm EDT. This is when it is precisely opposite the Sun. When it rises almost due east Sunday evening, about 15 minutes after sunset, the moon will actually be waning, although to the viewer's eye it will look full, just as it will seem to appear Saturday evening, when it rises before the Sun sets. As the moon wanes next week, its rising time will slip further into the evening. Watching it rise around 10:00 pm EDT on Tuesday, March 18, you'll find it gathered with the planet Mars and Spica, alpha star of Virgo, the 15th brightest star in our sky.