The fourth full moon in any farming season has been called a blue moon – but we were only interested in real blue moons.
We found out that when particles in the air are the right size to scatter red light waves, the others will get through and make the moon appear blue.
This happened when Krakatoa erupted in Indonesia in 1883. Some of the ash particles in the clouds were one-millionth of a metre in diameter – the right size to scatter the red light.
If you like investigating these strange things, have a look at this website for some stories and pictures. It really does happen!
But we needed a blue moon in the UK in 1950 when the events in Scordril were unfolding to a climax. So we investigated further and turned up a gem.
Patrick Moore, in his book Guide to the Moon (published in 1953), described several sightings of blue moons in 1944 in America, in 1949 in Queensland, and in England on September 26, 1950. According to Moore who witnessed the 1950 event:
“The moon was in a slightly misty sky and had a kind of lovely blue colour comparable to the electric glow discharge. I never saw something similar before.”
Another witness said:
“It was BLUE, not bluish or powder blue, but BLUE.”
There had been a heavy season of forest fires in Canada and the smoke from these was assumed to have caused the effect, even as far afield as the UK.
And so another element of the Scordril plot was set up. We moved the blue moon forward a few weeks to suit our timeline, and then used it to bring in an event that frightened the life out of Morris when he he was outside his tent staring in amazement at a very blue moon over Traprain Law.