How Often Do Blue Moons Happen? The Truth Makes The Phrase “Once In A Blue Moon” Take On An Entirely Different Meaning

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In case you were worried 2018 was going to be anything but the magical reprieve we all need from 2017, I have good news for you: The year is starting off with an event that feels quite magical. While we got to witness a full moon on New Year's Day, Jan. 31 is offering another full moon that is totally next level — because, not only will it be a full moon, but it'll also include a trifecta of lunar events. On the final day of the month, a blue moon, super moon, and total lunar eclipse will occur, all at the same time. Happening for the first time in over 150 years, the Super Blue Blood Moon is a can't miss, once in a lifetime occurrence. But, it's worth asking — how often does a blue moon happen?

The term blue moon was originally coined as a reference to a third full moon happening within the same season. However, in the past 20 years, the definition of blue moon has changed, and the term is now commonly used to describe the second full moon in a calendar month. In this case a full moon occurred on New Year's Day, and now another is happening on January 31. So, the upcoming full moon will be referred to as a blue moon.

So, what causes full moons anyways? Approximately every 28 days a full moon happens when the moon reaches the point in it's rotation where the Earth is directly in between it and the sun. As the timing is slightly shorter than a calendar month, the rotation is not tied to our calendar, meaning the day a full moon is visible changes.

How Often Does A Blue Moon Happen?

The last blue moon was visible two and a half years ago, on July 31, 2015. This period of time between blue moons is quite typical, however, this year we will only have to wait two months as another blue moon is falling on March 31. This occurrence is far more rare, as two blue moons occurring in the same year will not happen again until 2037.

The next exciting lunar event taking place on January 31 is closely related. Coined in 1979 by astrologer Richard Nolle, the moon is referred to as a supermoon when a full moon occurs no farther than 226,000 miles away from Earth. This is one of the closest points the moon gets to Earth while on it's rotation. So, while the term supermoon may sound a bit intimidating, all it means is that you will be able to see the moon a bit better.

While seeing a super moon isn't so uncommon, really great ones are. In 2017 a super moon lit up the sky at the closest distance since 1948. It won't be until 2034 that a supermoon comes that close again. Luckily, the last lunar event making up Jan. 31's moon so special is guaranteed to make it look just as cool: A total lunar eclipse is set to occur, which means the Earth, moon, and sun will be perfectly lined up. Any derivation from a perfect line and it's only a partial eclipse. Unlike a solar eclipse you don't need any sort of glasses to watch it — you can just look up at the moon and view its slightly reddish tinge, proof that the sun is reflecting against the moon and giving it a "blood"-like color. (Hence, Super Blue Blood Moon.)

Considering a blue moon, super moon, and a blood moon are all happening at once on Jan. 31, the Super Blue Blood Moon isn't a lunar event to miss. Bundle up, and head outside on the night of Jan. 31 to check it out in all its glory.