Rare moonbow photographed over Tweed Valley

A TWEED Valley resident has captured a rare moonbow near Uki after spotting the unusual nighttime phenomenon while driving home through light rain.

Gus Kidman said he was travelling along Smiths Creek Road when he noticed the lunar rainbow forming across the valley.

“It was kind of rainy and such, and cloudy, as you’d expect, in the valley,” he said.

“I was on Smiths Creek Road pretty much looking at the mountain as I was turning into my driveway.”

Kidman said the moonbow appeared unlike a traditional daytime rainbow and stood out against the dark sky.

“It was kind of like a cloud, but it had more of a colour to it, and it was in a rainbow shape,” he said.

“It had some kind of a glow off the rainbow through the cloud.”

“It was more just like you could see colour in the sky because it was nighttime.”

“It wasn’t like distinct red and blues like you see in the day.”

Kidman said he initially doubted his phone camera would capture the sight.

“I was like ‘What’s that?! It’s a rainbow!’,” he said.

“And then I’m like, ‘Oh I’ll take a photo of it.’.”

“I doubted it would come up on camera, but it did.”

Senior meteorologist Angus Hines from the Bureau of Meteorology said moonbows formed in much the same way as rainbows, but relied on moonlight rather than sunlight.

“It’s very much the nocturnal cousin of the rainbow and much of the same principles that cause a rainbow still apply,” Hines said.

He said moonbows required moisture in the atmosphere, a visible moon and precise alignment between the moonlight, droplets and observer.

“It has to come in from a certain angle – so the moon has to be fairly low in the sky, it can’t be right up overhead, that’s too steep of an angle,” he said.

“And then aside from that, really, it’s all about the alignment of the moonlight, the droplets, and where the observer is viewing from.”

Hines said moonbows often appeared white or grey because moonlight was much dimmer than sunlight.

“When it comes to moonbows, specifically, as opposed to rainbows, a lot of times the light is much dimmer,” he said.

“So the resulting bow is much dimmer as well.”

But Hines said cameras could reveal colours that were difficult to make out with the naked eye.

“People have found if you do kind of long exposure images and you get a lot of light, then it does still divide up into the colours in the same way that a rainbow does, just with the naked eye, it’s often, it’s too dim to really make out those colours,” he said.

Hines said moonbows were uncommon and often went unnoticed because conditions needed to align almost perfectly.

“My gut instinct is that a lot of times when the conditions are right for a moonbow, if it is quite dim, you really have to be looking pretty intently at the right place to even see it,” he said.

“In order to get one where the moon’s bright enough and everything else sort of lines up, conditions have to pretty much be bang on perfect, because its rare.”