However, there are rare occasions when the moon can appear to turn blue. According to the Science@NASA blog, observers have reported the moon having a bluish tint following volcanic eruptions. These explosions send particulates (like ash and smoke) into the air that scatter red light, but let blue light through, creating a natural blue filter and giving the moon a sapphire complexion.
"Back in 1883, for example, people saw blue moons almost every night
after the Indonesian volcano Krakatoa exploded with the force of a 100-megaton nuclear bomb," according to the Science@NASA statement. "People also saw blue-colored moons in 1983 after the eruption of the El Chichón volcano in Mexico. And there are reports of blue moons caused by Mount St. Helens in 1980 and Mount Pinatubo in 1991."
Particulates created by forest fires can also create a blue filter in the sky, according to NASA.
"A famous example is the giant muskeg fire of Sept. 1953 in Alberta, Canada," NASA officials explained in the statement. "Clouds of smoke containing micron-sized oil droplets produced lavender suns and blue moons all the way from North American to England. At this time of year, summer wildfires often produce smoke with an abundance of micron-sized particles — just the right size to turn the moon truly blue."