For those living in Europe, Africa, Asia and Australia, viewing the "Blue Moon" will be possible after midnight of June 1.
Some almanacs and calendars assert that when two full Moons occur within a calendar month, that the second full Moon is called the "Blue Moon."
For example, if you live London, you will officially have to wait until June 30 to declare that the moon is blue.
According to astronomers and cosmologists, May 31 will brings us the second of two full Moons. The full Moon that night will likely look no different than any other full Moon. But the Moon can change color in certain conditions.
After forest fires or volcanic eruptions, the Moon can appear to take on a bluish or even lavender hue. Soot and ash particles, deposited high in the Earth's atmosphere can sometimes make the Moon appear bluish.
Smoke from widespread forest fire activity in western Canada created a blue Moon across eastern North America in late September 1950.
In the aftermath of the massive eruption of Mount Pinatubo in the Philippines in June 1991 there were reports of blue moons (and even blue Suns) worldwide.
The phrase "Once in a blue Moon" was first noted in 1824 and refers to occurrences that are uncommon, though not truly rare. Yet, to have two full Moons in the same month is not as uncommon as one might think. In fact, it occurs, on average, about every 32 months. And in the year 1999, it occurred twice in a span of just three months, reveals a report in Live Science.
It was not until the year 1999 that the origin of the calendrical term "Blue Moon" was at long last discovered. It was during the time frame from 1932 through 1957 that the Maine Farmers' Almanac suggested that if one of the four seasons (winter, spring, summer or fall) contained four full Moons instead of the usual three, that the third full Moon should be called a "Blue Moon."
But thanks to a couple of misinterpretations of this arcane rule, first by a writer in a 1946 issue of Sky and Telescope magazine, and much later, in 1980 in a syndicated radio program, it now appears that the second full Moon in a month is the one that's now popularly accepted as the definition of a "Blue Moon."