A "blue moon" is a term used to describe a phenomenon

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A "blue moon" is a term used to describe a phenomenon when there are two full moons occurring within the same month. This is a relatively rare occurrence, happening about once every 2.7 years. The term "blue moon" does not actually refer to the color of the moon, as the moon typically appears in its normal color. Instead, it's a colloquial expression used to define this particular lunar event. However, it's worth noting that the date you mentioned, "31 Aguste," seems to contain a typographical error, as there are only 30 days in August. a "blue moon" usually refers to the occurrence of an additional full moon within a calendar month. The term itself doesn't have an astronomical significance, but it's more of a cultural and folklore reference. If you're referring to the occurrence of a blue moon in the year 2023, I don't have access to specific dates beyond my knowledge cutoff in September 2021. I would recommend checking a reliable astronomical source or a calendar closer to that time to determine if a blue moon is expected in 2023.