I am looking at the full moon right now from North Devon in UK. It appears to have a white then orange and a fainter blue aura around it. I’ve not seen this before (perhaps I havn’t been looking). What causes this and why?
I used to notice when I was a kid swimming at night the moon appeared to have an aura around it, that was because of having water in my eyes though.
I’ve heard an old wise tale about seeing an aura around the moon meant it was going to snow.
It’s called a lunar halo. It is caused by refraction of light by water droplets in the atmosphere, in much the same way that a rainbow is caused, and there is a solar halo, as well, at times. if you see it again, place your closed fist at arm’s length at one side of the halo and see how many fists it takes to get across to the other side. It should be two, plus about two fingers worth, 22.5 degrees diameter (same for the solar halo). At times the solar halo is broken into two very bright spots 11 degrees or so either side of the sun: these are popularly called “sun dogs”. If thin ice crystal clouds are the cause there is usually no coloration associated with the halo.
The orange is probably due to various particles in the atmosphere, dust and the like. The halo is caused by moonlight being reflected and refracted by ice crystals or water droplets in high-level clouds.
Looking at the full moon tonight near Spokane Washington. I noted a rather impressive blue aura — that fluctuates in size and intensity. My wife can’t see it at all. Frankly, I have never seen this phenomenon before. Not likely to snow as it is early July.