what does blue moon means &when it occurs?

Answer 1

Blue moon refers to the second full moon in a calendar month, or to the third full moon in a season with four full moons when it would normally have only three. The month-based definition is more modern, while the seasonal definition is more historical. The term "blue moon" can also refer to a physically blue appearance of the moon, caused by atmospheric pollution.

Answer 2

When the Indonesian volcano Krakatoa exploded in 1883, its dust turned sunsets green and the Moon blue all around the world for the best part of two years. In 1927, the Indian monsoons were late arriving and the extra-long dry season blew up enough dust for a blue Moon. And Moons in northeastern North America turned blue in 1951 when huge forest fires in western Canada threw smoke particles up into the sky.

So, by the mid-19th century, it was clear that visibly blue Moons, though rare, did happen from time to time — whence the phrase "once in a blue Moon." It meant then exactly what it means today, a fairly infrequent event, not quite regular enough to pinpoint, and today it is still the main one.

Answer 3

It's actually a phenomenon caused by the presence of large quantities of suspended particles in the atmosphere which selectively remove the longer lunar to solar visible wavelengths more than the blue or green wavelengths. In addition, it's also the second full moon in a calendar month, or the third full moon in a season containing four.

Hope that helps!

Answer 4

If you have two full moons in a same month, the second full moon is called Blue Moon.
Because that phenomenon only happens once every 32 months.

Answer 5

A "blue moon" is when a second full moon occurs within one month ( ex. two full moons in July, etc.)

Answer 6

All it is is the second full moon in the same calendar month. It usually happens twice a year or so and means no more than that.