Maria Storr had a feeling.
It was Monday and the Inuvik resident had spotted a sundog, a bright spot in the sky on one or both sides of the sun, caused by the refraction of sunlight by ice crystals in the atmosphere, during the day.
“And I thought, I bet you there’s going to be something happening with the moon tonight,” she said.
Sure enough, that night she saw something she had never seen before, a lunar halo.
She first spotted it while she was on her way to deliver some food to her grandchildren. On her way back home, she said the lunar halo got brighter.
Even though it was about -40 C that night, she looked for the best place to take a picture of it, and found it at the corner of Inuit Road and Firth Street.
“My breath was taken away, seeing that it was just so beautiful,” she said.
‘Incredibly bright’
Alan Clark, a retired professor of physics and astronomy at the University of Calgary who also calls himself a halo enthusiast, saw the photo.
“If it were around the sun, I would not be particularly excited by it,” he said.
“But the impressive thing about this is that it was in fact the moon, and yet the halo display is incredibly bright.”
He said there’s a famous picture taken in 1972 in Saskatoon of a sundog that lasted all day.
The picture is famous, said Clark, because the halo is much brighter than most other ones.
“This display that Maria photographed for the moon is the equivalent of that. It is a fairly common display, but it’s very bright for a moon display,” he said.
He added he thinks the halo probably lasted “for quite some time through the night.”
Light hitting crystals in the atmosphere
Clark is also a member of a group of people who connect on the internet to look at and discuss different halos.
He said they receive about one picture a month of a lunar halo, but they’re not as bright as this one.
Clark said that if you see a sundog during the day, it’s almost guaranteed there’ll be a moondog at night.
“There’s no difference,” he explained. “It’s just the same effect. The light moving up into the sky hits the crystals in the atmosphere, and that combined effect of millions and millions of these crystals is to refract the light like a prism back toward your eye.”
He added the light appears to come from 22 degrees on either one side or the other of the sun or moon.
The crystals, said Clark, are flat plates of six sides and they usually fall with their flat faces horizontally.
“However, if there’s some wiggling in that direction, then that light spreads out around a 22 degree halo, which Maria saw in her image,” said Clark.
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