The full moon in the sky tonight is the first time a full moon has occurred on Halloween in Ireland since 1955, and another one isn't expected again on the spookiest night of the year until 2039. This will also be a "blue moon", a term used not to describe the moon's color, but to indicate that it is the second full moon of the month.
"The Halloween full moon probably only happens a few times every century and it won't happen again in Ireland and the United Kingdom until 2039", he said to the BBC.
It was only in the eighth century that Pope Gregory III designated November 1 as All Saints Day, and the evening before - October 31 - was dubbed All Hallows Eve.
A rare and visually spectacular sight, the sight of the rare Blue Moon will provide at least some entertainment on a Halloween when trick or treating is prohibited. It's named not for its colour, but for its rarity. The leftover days of the year keep adding up until once every two -and-a-half years, 13 Full Moons appear in one calendar year. This means that tomorrow's full moon shall be visible from nearly every part of Earth, although some not-so-lucky areas will still miss out on it. Generally, this happens when there are 31 days in a month.
This issue published an an article called Once in a Blue Moon by James Hugh Pruett, who referred to the 1937 Maine Farmer's Almanac, but with a simpler definition.
At 2 a.m. Sunday, while Halloween observance may yet be in full swing, the hour magically becomes 1 a.m. The moon looks blue very rarely "due to particles thrown into the atmosphere by natural catastrophes", says the NASA.
A Blue Moon is rare but what would you say when it coincides with Halloween? However, the skywatcher says with the full moon so close to the planet in the sky it will be hard to see without binoculars.
Traditionally, hunters would be out hunting for food this time of year using the light of the moon to help them.
As the astronomer explained, a full moon is also when the moon is at opposition with the Sun, "so Uranus is close to the Moon that night also".