"He was. Ertene left the parent sun with only the light-shield. The light-shield, Guy, is a screen of energy that permits radiation to pass inwardly but not outwardly. Thus we collect the radiation of all the stars and lose but a minute quantity of the input from losses. That kept Ertene warm during those first years of our wandering. "It also presented Ertene with a serious problem. The entire sky was faintly luminous. It was neither night nor day at any place on Ertene, but a half-light all the time. Disconcerting and entirely alien to the human animal. Evolutionary strains might have appeared to accept this strange condition, but Timalas decided that Intis, the lesser moon, would serve as a sun. He converted the screen slightly, distorting it so that the focal point for incoming radiation was at Intis. The lesser moon became incandescent, eventually, and serves as Ertene's sun. It is synthetic. The other radiations that prove useful to growing things and to man but which are not visible are emitted right from the inner surface of the light-shield itself. Intis serves as the source of light and most of the heat. It is a natural effect, giving us beautiful sunrises and peaceful sunsets. The radiation that causes growth and healthful effects is ever-present, because of the screen. Some heat, too, for that is included in the beneficial radiation. But the visible spectrum is directed at Intis along with a great quantity of the heat rays. Intis is small, Guy, and it is also beneficial that the re-radiation from Intis that misses Ertene and falls on the screen is converted also. Much of Ertene's power is derived from the screen itself--a back-energy collected from the screen generator." "So the effective sun is the result of an energy shield? And this same shield prevents any radiation from leaving this region. I can see why we haven't seen Ertene. You can't see something that doesn't radiate. But what about occultation?" "Quite possible. But the size of the screen is such that it is of stellar size as seen from stellar distances. It is but a true point in space." Charalas smiled. "I was about to say a point-source of light similar to a star but the shield is a point-source of no-light, really. Occultation is possible but the probabilities are remote, plus the probability of a repeat, so that the observer would consider the brief occultation of the star anything but an accident to his photographic plate." "Don't get you on that." "It's easy, Guy. Take a star-photograph and lay a thin line across it and see how many stars are really covered by this line--which is of the thickness of the stars themselves. Too few for a non-suspecting observer to tie together into a theory. No, we are safe from detection." "Detection?"