A blue moon happens when a season has four full moons instead of the regular three. The third moon of the four moons is then labelled a blue moon. In essence, nothing astronomical sets it apart from the full moon. This moon apparently has nothing to do with the actual colouration of the satellite.
The name Blue Moon is just one of the naming conventions from old American farmers. For example, January’s full moon is called the “Wolf Moon” because, apparently, wolves were often heard at winter moons back in the day.
According to astrophysicist and director of the Virtual Telescope Project in Rome, Gianluca Masi,
“The name ‘Blue Moon’ has nothing to do with the colour of the Moon. Every two to three years we have 13 full Moons within a year. This way, we can have four full Moons during a given season or two full Moons in a given month.”
More recently, we define Blue Moon as the second full moon that falls within the second calendar month. This means that if there is a full moon on the first day of any month, except February, then there will be a blue one four weeks after.
Blue Moon, according to experts, more recently is dependent on the regular calendar that we use. This also suggests that blood moons are not exactly moons that are bloody and supermoons are very neat moons.
Blue moons are just the same as every other full moon but this time with a fancy title. On Saturday, 18th May 2019, the whole world experienced the rare moon. It is going to be the last seasonal blue moon until August 2021.
On rare occasions, blue moons happen in one year. This extremely rare occurrence will happen in 2048 where there will be a monthly blue moon in January and another seasonal one in August. At certain times though, the moon can appear blue under some rare conditions.