30/05/2026
Tonight (31st May 2026) is the second full moon in May, making it a Blue Moon.
It is not yet known exactly why the second full moon of the month is called a Blue Moon. Some sources even said that the phrase "once in a blue moon” came from this definition, but this is widely considered to be misinformed.
It is possible that the phrase refers to an actual visually blue moon, which is only possible in very rare atmospheric conditions, like during volcano eruptions or big wildfires.