hey are refugees. Bruce, from a planet that circled about the star that we know as Alpha Centauri, a star that is the nearest of all our stellar neighbors, being only four and a third light years distant. Their home planet was disrupted by a colossal engineering experiment of the Centaurians themselves, the only survivors being a group of fifty who escaped in a space ship just before the catastrophe.
"There were no other habitable planets in their own system, so in desperation these refugees sped out across the void to our solar system in the hope of finding a new home here. They reconnoitered our Earth secretly and found it ideal. But first they believed that they must conquer the life that already held this Earth. To do this, they struck with the Green Sickness.
"The rays that are turning the moon green emanate from the space ship hovering up there some fifty thousand miles from the moon itself. The Centaurian's rays, blending with the sunlight striking the disc of the full moon, are intensified in some unknown way, then reflected across the quarter of a million miles to the Earth, to flood this planet with virulent radiance.
"The green moonlight is radioactive in nature, and overcomes animal life within a matter of fifteen minutes or less. The rays are most powerful when the moon is in the sky, but their effect continues even after it has set, because as long as the green moonlight strikes any part of the Earth's atmosphere the entire atmospheric envelope of the planet remains charged with the paralyzing radioactive influence.
"Earth's inhabitants are not dead. They are merely stupefied. If the green rays were to cease now, most of the victims of the Green Sickness would quickly recover with little permanent injury. But, Bruce, if that evil green moon blazes on for twenty-four hours more, the brain powers of Earth's millions will be forever shattered. So weakened will they be by then that recovery will be impossible even with the rays shut off, and the entire planet will be populated only by mindless imbeciles, readily available material for the myriads of monstrous hybrids that the invaders will create to serve them.
o-night you saw the hybrid that the invaders sent to recapture Ruth and me. It was a fit specimen of the grisly magic which those devils from outer space work with their uncanny surgery and growth-stimulating radioactive rays. The basic element of that monster was an ordinary tarantula spider, with its growth incredibly increased in a few short hours of intensive ray treatment in the Centaurian's camp. The half-head grafted to it was that of a human being. They always graft the brain cavity of a mammal to a hybrid—half heads of burros, horses, or even dogs, but preferably those of human beings. I think that they prefer to use as great a brain power as possible.