Blood Moons in astronomy. In astronomical lore, all the full moons have names. The names typically coincide with months of the year, or seasons.
One of the most famous moon names is the Hunter’s Moon. It is the the full moon immediately following the Harvest Moon, which is the full moon occurring most closely to the autumnal equinox.
The Hunter’s Moon, in skylore, is also sometimes called the Blood Moon. Why? Probably because it’s a characteristic of these autumn full moons that they appear nearly full – and rise soon after sunset – for several evenings in a row. Many people see them when they are low in the sky, shortly after they’ve risen, at which time there’s more atmosphere between you and the moon than when the moon is overhead. When you see the moon low in the sky, the extra air between you and the moon makes the moon look reddish. Voila. Blood moon.