What is the Origin of the Phrase ‘Once in a Blue Moon’?

Once in a blue moon means —

• very rarely;
• highly infrequently;
• after an exceptionally long time.

Some people believe that an actual blue moon is the appearance of the second full moon in the same calendar month. It happens every 32 months, i.e. a period of about two and a half years.

Some others believe that in 1928, a volcano erupted so explosively that it spewed lava, smoke, dust, and ash in such copious amounts that their residue could be seen in the sky for two and a half years, which made the moon appear bluish.

For example —

“I don’t like eating out, so I dine in restaurants once in a blue moon just for a change of taste.”

I hope you understood the example.

I hope you found this story interesting. If you did, buy my full course on Udemy, or watch it for free on Skillshare by signing up here. This course covers nearly 380 idioms with their origins and backstories.

Hi, I am Gauri Shanker, a Vocab teacher and enthusiast. I teach vocabulary in a fun and engaging way. You can check out my courses here.