Smoky Moon

The Moon seen through smoke from a nearby forest fire. CREDIT: Stuart

About two years ago I posted a picture of a rather orange looking Moon with an explanation of why this happens. I pointed out that the Moon would look more orange if there was more dust or pollution in the air. Now, I've finally got chance to see my comments in action.

Today, a month-old fire in the Los Padres National Forest flared up and caused rather a lot of smoke to head out towards the coast. That has coincided with an almost full Moon.

If you see the Moon through a big black rain cloud, the Moon doesn't tend to be reddened. However, a black cloud of smoke does redden the Moon. That is because the particles in the smoke cloud are the right sort of size to scatter out the blue light much more than the red light. The result is rather pretty and a nice demonstration of Rayleigh scattering.