Blue Moon

What is a Blue Moon?

  • blue moon is what people call the second of two full Moons that appear during the same month.
  • second full Moon can appears within the same month because full Moons occur about every 29.5 days.
  • so if a full Moon occurs in the first day or two of a month, except for February, a second full Moon can occur during one of the last days of that month as well.
  • for example; Tuesday 2nd January and Sunday 31st January = Blue Moon.
  • it doesn’t actually look blue.

Who says “Blue Moon”?

  • Well,….  a mistaken definition in the March 1946 edition of Sky and Telescope magazine claimed the blue moon fell on the second full moon of the calendar month  –  this mistake caused widespread misunderstanding until it was finally corrected in 1999.


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