A BLUE MOON is expected to appear in the sky this Saturday night, lining up with Halloween for the first time in decades.

The full moon in the sky on Saturday is the first time a full moon has occurred on Halloween in Ireland since 1974, and another one isn’t expected again on the spookiest night of the year until 2039.

It will be the second full moon of this calendar month, making it a “Blue Moon”.

Astronomy Ireland is encouraging people around Ireland to take photographs of the moon on Halloween night.

The Astronomy Ireland magazine hopes to publish photos and comments from Irish people marking the rare blue moon.

Chair of Astronomy Ireland David Moore said that “even cameraphones can take great photos of the Moon these days, either close up, or against a backdrop of buildings, statues or landscapes”.

Speaking to TheJournal.ie, Moore said that there “hasn’t been a full moon on Halloween in most people’s lifetimes”.

“It’s definitely unique. 2020 is turning out to be a very weird year altogether, and here’s an astronomy angle to that,” Moore said.

“The definition of a full moon is that it’s directly opposite the sun in the sky. So when the sun goes down on the west horizon, the moon is just rising on the east horizon, and then it stays up all night until the moon is going down on the west and the sun is rising in the east,” he said.

Moore said that there is a chance of seeing the full moon once the sky is dark until the next morning at dawn.

For anyone eager to take a photo, Moore advises being patient “even if the skies are a bit cloudy”, because all it takes is for the moon to “pop out during a break in the clouds, and you’ve got it”.

Astronomy Ireland has told its readers that that “Saturday is also the date that the distant dim planet Uranus is at opposition to the Sun (and effectively a Full Moon is when the Moon is at opposition with the Sun), so, Uranus is close to the Moon that night also”.

“Uranus is 3.8 degrees above the Moon that evening but at magnitude +5.7 and with a Full Moon so close you probably won’t even be able to see it with binoculars, and certainly not the naked eye. Still, it is nice to know Uranus is there to celebrate such a triple whammy!” 

This week, Mars has appeared in the sky close to the moon, and is visible over Ireland.