Greengates Builders Merchants

Blue Moons

'Once in a blue moon' is not just a phrase we use for those occasional treats or chores.

It is also a rare statistical quirk which occurs when a full moon occurs twice in a calendar month.

And Friday was the day, when for the first time in two years we were treated to our second full moon in August, thanks to the moon last reaching its peak on August 2.

The moon was at its fullest - reflecting the maximum sunlight from our vantage point on Earth - at 2.59PM.

The reason why we call it a 'blue moon' is lost to history, although the Farmers' Almanac would always note an occurrence during the 18th century.

With a full moon occurring once every 29 days, and a month topping out with a maximum of 31 days, the combination is a rare one - occurring around once every two-and-a-half years.

Sadly, the moon did not take on a different hue. Barring volcanic eruption, it will remained as white as ever.

If a volcano had erupted, then ash in the sky has been known to play visual tricks with the sun and the moon.

When Krakatoa erupted in Indonesia in 1883 - where ash soared right into the upper echelons of the atmosphere, blue moons were reported around the world, for up to two years.

Krakatoa's ash is the reason. Some of the ash-clouds were filled with particles about 1 micron (one millionth of a meter) wide - the right size to strongly scatter red light, while allowing other colors to pass.

White moonbeams shining through the clouds emerged blue, and sometimes green.

Blue moons persisted for years after the eruption. People also saw lavender suns and, for the first time, noctilucent clouds.

“Well thankfully there were no erupting volcanno’s on Friday, but did you see a blue moon”.

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