The second full Moon in the month has commonly become named a ‘Blue Moon’. However, this term is not used correctly and was originally published as a mistake by an amateur astronomer. It has become populary adopted but is totally different to the astronomical Blue Moon.
ASTRONOMICAL BLUE MOON
Describes the third of four full Moons which fall within one of the Earth’s seasons:
In early almanacs, the sequence of full Moons through the year were assigned names according to the seasons in which they fall. For example, the first full Moon of summer was called the Early Summer Moon, the second was the Midsummer Moon, and the last the Late Summer Moon. Usually only three names are needed for the full Moons in each season. If a fourth full Moon fell within the same season, one of them was left without a name. This additional full Moon was named the Blue Moon - this would be the third of the four full Moons.
Astronomical Blue Moon
The first and the last Full Moon of the season will be near the solstice or equinox.
Popular Blue Moon
Two Full Moons in one month which will be at the beginning and the end of the month.
Sometimes, we have a Blue Moon Eclipse or a Super Blue Moon. At these times the media and press get very excited about something that was originally a mistake! Just reminding us the question the validity of the information we are given via the media!
The Next Astronomical Blue Moon is on 18th May 2019.