A rare blue moon will illuminate the sky tonight, coinciding with Halloween for the first time in decades.
The full moon will rise tonight after sunset on the last day of October.
It is the second full moon this month, which means that it is officially a “blue moon”. The first full moon was October 1.
The presence of two full moons in one calendar month – or a blue moon – is a rare phenomenon that occurs roughly every two and a half years.
The last time a full moon was seen in all time zones around the world was on Halloween, as it will be tonight, it was 1944.
It is the first time since 1974 that star-watchers have been able to see a full moon across Ireland and the United Kingdom, according to Astr Irelandonomy.
Ireland’s astronomer David Moore said Londoners should try to see the moon tonight, because it won’t happen again for another 19 years.
He told the BBC: “It is possible that a full moon on Halloween will happen a few times every century and it will not happen again in Ireland and the United Kingdom until 2039.”
“You associate Halloween with ghosts and ghosts, but this year there will also be two werewolves due to a full moon.
“So it’s good fun for the general public and we hope everyone gets excited.”
The term Blue Moon is believed to have been used for the first time to mean a second full moon in a month after a misinterpretation by an amateur astronomer in 1946.
A blue moon was supposed to mean a third full moon in a calendar month as four moons were expected.
But James Hugh Pruitt is said to incorrectly refer to the second moon in one month as a blue moon in an article in Sky & Telescope magazine – and the name is stuck.