Lunar Halo Cross.

Question

I noticed the moon right now has 4 rays of light from it in 4 directions 90° apart, like a cross +.

I guess it’s something about light refracting through ice crystals in the atmosphere, but how does it form such a perfect, distinct cross?

In: Planetary Science

Answer 1

This sounds like a phenomenon called Moon Dogs and they are located 22° away from the Moon in the horizontal. When combined with a 22° halo, it gives this cross effect.

The normal halo effect is caused by hexagonal columns of ice in cirrus clouds. This Moon Dog effect is rather caused by hexagonal plates of ice, rather than columns.

Moon Dogs are quite rare, even when compared so the extremely rare Sun Dogs