'Exceedingly rare' super blue moon to be seen this week

A supermoon occurs when a full moon is near its closest point to the Earth in its orbit. Picture: Arne Dedert/dpa via AP

Stargazers will be in for a treat this week as an extremely rare supermoon will be visible on Tuesday, Wednesday and Thursday nights in what will be a “historic event” across Ireland.

On Wednesday night, the full moon will come in the form of a blue moon and a supermoon, giving rise to a super blue moon, in an event that hasn’t occurred since 2009 and will not re-appear until 2037.

A blue moon is when there are two full moons in a month, with the second one given the name 'blue moon'. This occurs every two to three years. A supermoon occurs when a full moon is near its closest point to the Earth in its orbit.

When this happens, the moon appears slightly bigger in the sky, and is around 30% brighter. This sight occurs approximately three times every year.

According to Astronomy Ireland CEO David Moore, to have a blue moon coincide with a supermoon to give rise to a super blue moon is "exceedingly rare". He is urging the people to go outside and witness the phenomenon in its entirety this week.

"As there are 12 full moons every year that means there have been 168 full moons to give one super blue moon. This is how rare super blue moons are," he said.

"This is why we want all seven million people on this island to witness this unique event,” he added.

Wednesday night's super blue moon will prove to be an even more special sight, with the planet Saturn expected to be visible just above the moon. Mr Moore said this sighting of Saturn coupled with the super blue moon, is a "once in a lifetime, or rarer" event.

He said:

This is all the more reason that people should go out and watch the incredible sight of Saturn close to a blue supermoon.

The ideal time for those to catch sight of this event is just as the moon is rising. In Ireland, this will occur on Tuesday from 8.15pm, Wednesday from 8.35pm and Thursday from 8.50pm onwards.

Those situated further in the west may see the moon rise up to 20 minutes later than this, he explained.

“So we've had to wait 14 years for the last super blue moon and we'll have to wait another 14 years for the next super blue moon,” Mr Moore said.

Technically, the exact full moon can only be seen from Ireland on Wednesday night, Mr Moore said. However, to the naked eye, the moon looks' full the night before and after. 

"This is great for us as it helps combat the Irish weather so we are urging everyone to look east at sunset to watch the super blue moon rising directly opposite on the horizon where the sun sets. This should give the most impressive view due to an extra effect 'Moon Illusion'," he added.