This month's full moon, which rises on Tuesday (Aug. 20), is not just a Blue Moon — it's also the Full Sturgeon Moon, the Full Red Moon, the Green Corn Moon and the Grain Moon.

Today's full moon qualifies as a Blue Moon because it's the third full moon in a season with four (most seasons have only three). Historically, there have been two different definitions of a Blue Moon.

Technically, a Blue Moon is the third full moon in a four-full-moon season. However, a 1946 article in 'Sky & Telescope' magazine mistakenly defined it as the second full moon in a single month (since most months have only one full moon), and the definition stuck. Because August will have just this one full moon, it wouldn't meet the mistaken, though commonly used, definition, though it does qualify as a technical Blue Moon. [10 Surprising Moon Facts]

The moon's extra names come from traditional monikers for the full moon of a given month. A few hundred years ago, Native American tribes in what's now the northeastern United States kept track of seasons by ascribing particular names to each full moon. Later, European settlers added their own names for the full moons to the lexicon.

The annual August full moon has come to be known as the Full Sturgeon Moon, because the large fish called sturgeon can most easily be caught at this time of year. The name came from tribes who caught this fish in bodies .