Key Highlights
- The Blue Moon of May 2026 will occur on 31 May this year.
- This phenomenon happens when there are four full Moons in a season instead of the usual three.
- The term “Blue Moon” is often used to describe something rare, but its origin and definition have changed over time.
- Weather conditions can affect visibility of celestial events like this Blue Moon.
Astronomical Rarity in Your Backyard: The May 31st Blue Moon
You might think this is new, but… the term “Blue Moon” has been around for centuries. It used to refer to an extra full Moon occurring twice in one calendar month. But that’s not what it means now. According to astronomers at the Royal Observatory Greenwich, the modern definition – where a Blue Moon is simply the second full Moon of any given month – dates back only 80 years.
What Exactly Is This ‘Blue Moon’?
The May 2026 Blue Moon will be on Sunday, 31st. The lunar cycle is about 29.5 days long whereas most months are 30 or 31 days long. So, every now and then, we get two full Moons in a month. This definition – also known as the “monthly Blue Moon” – is actually a fairly modern interpretation, first printed in a 1946 edition of Sky & Telescope magazine and perpetuated by the game Trivial Pursuit.
The Term ‘Blue Moon’ Explained
It’s all about cycles. But don’t expect it to turn blue. The term “Blue Moon” has nothing to do with its actual color. However, there have been a few recorded times when the Moon did appear slightly blue due to ash particles in the atmosphere after large volcanic eruptions like Krakatoa.
Viewing Conditions and Weather
The Blue Moon will be officially “full” at 09:45 BST on Sunday morning. In the UK, it’ll be below the horizon then, so your best chances are Saturday night or the night of Sunday 31st. But check the forecast.
Cloudy weather patterns can spoil even the clearest of celestial shows.
So, grab a pair of binoculars and get ready to witness this rare spectacle. Just remember, it’s not really blue – but it sure is something worth looking out for.
