"In that case, why not go whole hog?" said Gonzalo. "If it's going to go science-fictional… Look, let me tell you how I see it. Murderer and Victim are eclipse buffs and Murderer is the better man-so make it Murderer who's on that plane, and taking the best eclipse photograph ever seen, using some new photographic gimmick he's invented. Then have Victim, against all expectation, beat him out. Victim goes to the Moon and takes the eclipse photograph there. Murderer is furious at being beaten, goes blind with rage and there you are."

Rubin said energetically, "An eclipse photo on the Moon?"

"Why not?" said Gonzalo, offended. "We can get to the Moon right now so we can certainly do it in a science fiction story. And there's a vacuum on the Moon, right? There's no air. You don't have to be a scientist to know that. And you get a better picture without air. You get a sharper picture. Isn't that right, Milton?"

Peterborough said, "Yes, but-"

Rubin overrode him. "Mario," he said, "listen carefully. An eclipse of the Sun takes place when the Moon gets exactly between the Sun and the Earth. Observers on Earth then see the Sun blacked out because the opaque body of the Moon is squarely in front of it. We on Earth are in the Moon's shadow. Now if you're on the Moon," his voice grew harsh, "how the Hell can you be in the Moon's shadow?"

Avalon said, "Not so fast, Manny; an eclipse is an eclipse is an eclipse. There is such a thing as a Lunar eclipse, when the Earth gets between the Sun and the Moon. The Moon is in the Earth's shadow in that case and the whole Moon gets dark.

"The way I see it, then, is that Murderer takes a beautiful photograph of an eclipse on Earth, with the Moon moving in front of the Sun. He has advanced equipment that he has invented himself so that no one can possibly take a better photo of the moon in front of the Sun. Victim, however, goes him one better by taking an even more impressive photograph of an eclipse on the Moon, where, as Mario says, there is no air, with the Earth moving in front of the Sun."