Today we can see the second full moon in July and a second one in a month is commonly referred to as a blue moon. The US Naval Observatory in Washington describes it as, " ... the third full moon in an astronomical season in which four full moons fall." It takes place at the same instant everywhere in the world, whether the moon is above or below the horizon.
The phenomenon appears about every 33 months, according to the
National Oceanic and Atmospheric Administration.
The most literal meaning of blue moon is when the moon (not
necessarily a full moon) appears to a casual observer to be
unusually bluish, usually caused by smoke or dust particles, which
is a rare event. Hence the saying of, "once in a blue moon."
Of course, today's blue moon is not actually blue, but this song
from the Marcells definitely is LINK,
and this one is all light, but not blue from Judith Durham and the