Elliptical Moon Halos

Elliptical Moon Halos

Luminous halos around the Moon are not unusual. Ice crystals in the air catch moonbeams and bend them into circular rings. On Dec. 3rd, however, Sophie Melanson of Moncton, NB, Canada, witnessed a Moon halo that was not circular, but rather elliptical:

"I was driving to my Intro to Photography class when I noticed this beautiful bright halo around the Moon," says Melanson. "I've seen moon halos many times before, but never this shape. Glad I was able to capture it and share!"
Although physicists have been studying ice halos for decades, not all are understood. "Elliptical halos are one of the puzzles," says atmospheric optics expert Les Cowley. " We can simulate them by invoking hexagonal plate-like crystals topped by almost flat pyramid faces.  However, the simulations do not fit very well and such crystals are unphysical. Crystal facets like to form along planes where there are lots of atoms or molecules – almost flat pyramids do not fit the bill at all.    Perhaps some peculiar distorted snowflake types instead?"
Whatever causes these elliptical halos, they are beautiful, and more could be in the offing. The Moon is waxing full this week, reaching peak brightness on Dec. 6. Bright moonlight can reveal rare halos that often go unnoticed--elliptical and otherwise. Sky watchers are encouraged to look around the Moon in the nights ahead.

From SpaceWeather.com