Moon halo lights up night sky but it could mean bad weather is on the way

The moon halo, spotted in Blackrock in Cork City. Picture: Dan Linehan

If you looked up at the sky on Tuesday night, you may have noticed a ring around the moon.

Many on social media have been commenting on the moon halo, with it being particularly prominent in Cork.

But what is it?

Speaking to the Irish Examiner, Astronomy Ireland said it is caused by ice crystals high in the atmosphere.

The ice crystals “bend the light from the Moon at exactly that distance from the Moon”.

Alan O'Reilly, from Carlow Weather, told the Examiner that the halo is often seen before a period of low pressure.

“Folklore would say they appear before a storm,” said Mr O’Reilly.

Just went out for a look myself and a really clear halo out there, check it out! pic.twitter.com/iL9ja3uVyt

— Carlow Weather (@CarlowWeather) March 23, 2021

And he might have a point.

According to Met Éireann rain is set to develop tomorrow in the west and it will spread eastward through the afternoon.

The forecaster says that the outlook for the rest of the week is “unsettled”.

Met Éireann is predicting that it will be “turning cold as the week progresses with some heavy blustery showers bringing the risk of some wintry precipitation at times”.

The @Space_Station passing the moon halo over #Cork a little while ago. @AstronomyIRL @CorkAstronomy @VirtualAstro @daraobriain pic.twitter.com/OkKcvDHgQw

— Darren Gale (@DarrenGale_1) March 23, 2021