Lunar coronas are haunting sky phenomena that create rings around the moon.
And as the Moon is waxing full, it’s a good time to look for them!
This beautiful specimen over Fort Frances, Ontario, was captured on October 2nd by Lauri Kangas:
How do these circles around the moon form?
Lunar coronas are made of moonlight diffracted by tiny droplets of water in the air. Sometimes the droplets are supplied by passing clouds. This time, however, they came in the form of fog. Rings around the Moon also form when ice crystals drift by, but those are ice halos, and they have a different appearance.
As described on Space Weather:
“Late in that evening the temperature dropped rapidly and a ground fog developed. I could see the tiny water droplets with my flashlight. These water droplets formed a beautiful corona around the Moon. To the naked eye the blue colored ring was awesome.”