They hardly caused the average citizen to lose a wink of sleep. Saturn looked like a working model preserved for school-room purposes. And the nebular hypothesis was a pleasant story to tell to children. But the contrary observations increased and multiplied--for the most part without getting into the newspapers--until now we have Vibert, with a host of competent astronomers ready to echo his words, saying, “A nebula giving rise to a solar system [is] an impossible hypothesis in the light of modern knowledge.” The hypothesis itself has not been altogether carried away to the bone-yard. Like an old and faithful horse, it has been taken from the shafts and turned out to grass so that it may enjoy its declining years in comparative peace. The latter pastures of the nebular hypothesis are sufficiently large, for it is being used now to help make stellar systems. As there is little in this far region save assumptions to drag around, the work is light. Fit ending for an honorable career. But astronomers have grown cautious. It is not likely that any of them will be rash enough ever again to impose the weight of a real star, let alone a system, upon the already broken back. They at least know the hypothesis for what it is--a hypothesis, and a dying one. Only laymen, half asleep over their Sunday supplements, now think it was ever anything else. And what has come to take its place? The “Big Star Theory.” An astronomer named Jeans brought forward this entry in 1919. He said that if a big star had ever come near enough to the sun, it might have caused a fearful tide of solar substance--a long arm of stuff more or less gaseous and very hot--to reach out millions of miles into space. And from this hypothetical arm (there were really two, but let us not complicate matters with details), broken into several pieces, the planets might have originated. This time there was plenty of force at hand, enough to satisfy all the equations which the mathematicians were likely to contrive. No need to try to think how the dust had been scattered. The force came from the big star, which Jeans made a very big star indeed, with a diameter of eight thousand million kilometers--say about twice the distance of the farthest planet from the sun. Anyway, there was a very big star concerned. Too big. The mathematicians could not use all the force thus put at their disposal. Dr. Harold Jeffers therefore reduced the mammoth to a diameter of a mere forty million kilometers.