Many of us may have heard of a "blue moon." It has been a part of our vocabulary for a long time. But what is a "blue moon?" It is a full moon, but it could not occur in February, although a blue moon could have a halo around it, though this does not in itself make it a blue moon.

A blue moon is the second full moon of the month. Now wait, you might say, you said earlier that a moonth is a month, and was based on the cycle of the moon, from full moon to full moon. How can it be then, that two full moons could occur in a month?

Well, the cycle of the moon is the culprit, it takes the moon 29.5 days to complete a cycle, that is slightly less than one month. There are more moon cycles in a year than there are months in a year. This eventually works out so that if there is a full moon on the first or second of the month, there will be another full moon 29.5 days later, and thus a blue moon.

This does not happen often, one occurs about every 30 months. And since it does not happen very often, the term "once in a blue moon" is sometimes used to convey the infrequency of events in our lives.

Q 5) Why does the Full Moon Appear Larger on the Horizon ?