Tonight at 6:45 p.m. PDT the moon will officially be full, according to an article on NBC News.
The full moon is called a blue moon based on the technical definition. It is the third full moon in a four-full-moon season.
According to the article, there is a second definition for the term Blue Moon -- the second full moon in a single month.
For more interesting facts about the Blue Moon, read the full article.