General knowledgeAsked by Anonymous from Mountain View, United States30 Sep 2026, 5:43 PM ISTUpdated
In one line
A Blue Moon is when there are two full moons in one calendar month.
Full moon — Lunar phase when the Moon is fully illuminated A full moon, which is what you see during a Blue Moon event. Image: Wikipedia
The rule
A Blue Moon is the second full moon in a single calendar month.
Let's understand it simply
Imagine you are looking at the full moon. Usually, you see only one full moon each month. But sometimes, because the moon cycle is about 29.5 days, you can get two full moons in one month. The second one is called a Blue Moon. The moon does not actually turn blue.
Remember it
A Blue Moon is just an extra full moon in a month, not a blue-colored moon.
