The full moon will rise over Baltimore at 6:20 p.m. Sunday, the third full moon since the winter solstice and the last of the winter season. Our ancestors might have known it as the Lenten Moon, or the Sap Moon, suggesting the first movement of sap in the sugar maples. The first people here called it the Crow Moon. Others knew it as the Worm Moon, for the first appearance of "castings" - worm poop - in the soil. It signaled renewed fertility, the revival of plant life and the return of migrating birds.