MOONGAZERS will be dazzled by the delights of the rarest full moon of the year tonight, the Blue Moon. 

Blue moons only occur once every 2.7 years and give rise to the term 'once in a blue moon'. 

There are usually three full moons each season, with a new full moon every 29.53 days - meaning occasionally there will be an extra full moon. 

The incredible spectacle will not appear blue in the sky however, but will be fully illuminated by the sun.

Skies are predicted to be mostly clear across the UK so everyone should be in with a good chance of spotting the rare phenomenon. 

Why is it called the Blue Moon or Sturgeon Moon?

Because this is the third of four full moons this season, it is known as a blue moon due to its rarity. 

There are usually three moons each season and this event only happens once every few years hence the term, 'once in a blue moon'.  

This full moon was known by early Native American tribes as the Sturgeon Moon because the large sturgeon fish of the Great Lakes and other major lakes were more easily caught at this time of year. 

Some Native Americans alternatively named this the Green Corn Moon and the Grain Moon. 

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When is the best to see it?

The Sturgeon Moon will be visible before sunset on Sunday, August 22 and will naturally appear brighter as the night gets darker. 

All you need to see it is clear night skies, something that the Met Office is currently predicting for most of the UK. 

South Wales Argus:

Why do full moons occur?

A full moon is when the moon appears as a complete circle in the sky, thanks to the sun’s rays lighting up the whole side of the moon that is facing the Earth.

This makes the full side of the moon visible to the naked eye, since it produces no light of its own.

When is the next full Moon?

The next full moon is the Corn Moon, also known as the Harvest Moon which will fall on September 21 and gets its name from the Native Americans as it indicated the right time to harvest corn.