'What's this?': Strange ring around the moon leaves stargazers perplexed

Brooke Rolfe
News Reporter

A peculiar ring around the moon has left people perplexed over what could have caused such a spectacle, with several sharing their own theories behind the mystical sight.

Wednesday night’s full moon provided more than a beautiful light show over Canberra, also displaying a mysterious glow in a perfectly shaped ring around the bright moon.

One resident shared images of their view to a Facebook group, asking if anyone knew what caused it.

While some chimed in to label it the work of things like ET or stadium lights, others suggested it was an earthquake warning or an indication there was rain to come.

One even said the number of stars inside the ring indicated how many days it would be until there was rain, saying the “tighter the ring, the closer to rain”.

This photo was taken in Canberra on Wednesday night and shows a distinct halo around the moon. Source: Facebook

The true reason however was not as complex as some suggested, and actually had nothing to do with aliens, earthquakes or electrical light.

Meteorologist Helen Reid from the Bureau of Meteorology said the halo appearance around the moon was due to prominent cloud coverage over the ACT in recent days.

“It’s just very fine cloud that would be scattering the light as it came through,” Ms Reid told Yahoo News Australia.

“With the moon light coming through quite well, there was probably an even covering for it to scatter the light, just like a rainbow sort of effect through the cloud droplet particles,” she said.

The occurrence of the natural event itself wasn’t particularly rare, but people looking up and taking notice of it was, according to Ms Reid.

She said in this instance it was likely spotted easier because of the full moon, giving the halo a more striking appearance than if it were a different shape.

A resident of Bungendore near the NSW ACT border also captured the moon halo Wednesday evening. Source: Facebook

“The combination of it (the full moon and halo) is not unheard of, but you could say it is a bit rare,” she said.

Others shared photos of the moon with the glowing ring around it from places in NSW in comments to the post - one from Bexley in Sydney, and another from Bungendore, close to the ACT border.

Rings also form around the sun

Bureau of Meteorology Senior Meteorologist Ian Shepherd said the effect could sometimes be seen around the sun as well as the moon, and when it was, it could be seen at an angle of 22 degrees.

“The ring is caused by scattering of light from the sun or moon by ice crystals high in the atmosphere. If these crystals are hexagonal in shape, the halo effect can be seen at an angle of 22 degrees around the sun or moon,” he told Yahoo News Australia.

“Sometimes there is also an iridescent rainbow effect as well.”

He added that rain was not necessarily indicated by this particular ring around the moon, but in southern parts of Australia it was often produced by high clouds ahead of an approaching cold front.

“In the tropics, the high cloud could be produced by thunderstorm clouds either nearby or at a long distance from the location of the halo, so the halo is not necessarily associated with rain at that (Canberra) location.”

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