"Because of the smoke, the sun was not very bright. I didn't need to use a filter," says Calubaquib. A day later, another lavender sun appeared over Arcata, California:
"The colors were not retouched; that is how it really looked," says photographer Mike Kelly.
What makes the sun lavender? It happens when the air is filled with particles measuring about 1 micron (10-6 m) across, a little larger than the wavelength of red light. Micron-sized particles scatter red light strongly, while letting shades of blue pass through. The mix of ash over El Sobrante produced a lavender hue, reminiscent of the great Alberta muskeg fires of September 1950. Believe it or not, the same physics can turn the Moon blue, but that is another story.