Calling All Meteorologists & Astronomers

What was that big ring around the moon early this morning? It was still drak dark. The ring’s radius was, oh, maybe 20 degrees. I pointed my forefinger at the moon and my thumb at the ring and the distance between them was about four inches.

4 Responses to “Calling All Meteorologists & Astronomers”

  1. Pooh Says:

    I think it’s a phenomenom related to the sun-doggies picture that Sam posted a while back. I think you are seeing the moonlight reflected/refracted through a high thin layer of ice crystals. I can’t remember why it forms a ring. Perhaps Val will chime in.

  2. Valdemort Says:

    Pooh’s got it right! It’s usually caused by some form of moisture (or sometimes dust) in the air that refracts light, thus forming the halo. : )

  3. Mark Says:

    Halos are caused by sunlight being refracted by cirro-stratus clouds. In the case of this lunar halo, the sunlight was first reflected off the gibbous moon, which was three days past full. Cirro-stratus clouds are thin clouds, very high in the atmosphere, and are composed of ice crystals. They bend light at a 22 degree angle, which creates a lunar halo that is 44 degrees in diameter. I have a prurient interest in astronomy.

  4. Frooggy Says:

    Thanks everyone. To The Marquis:

    holy mackerel! I was not even that far off on the diameter (20 degrees radius times two…)