When Conrad Wheeler had finished comparing the tapes, he got up from his chair and walked three times round the room. From the way he moved, an old hand could have told that Wheeler was a relative newcomer to the Moon. He had been with the Observatory staff for just six months, and still overcompensated for the fractional gravity in which he now lived. There was a jerkiness about his movements that contrasted with the smooth, almost slow-motion gait of his colleagues. Some of this abruptness was due to his own temperament, his lack of discipline, and quickness at jumping to conclusions. It was that temperament he was now trying to guard against.

He had made mistakes before—but this time, surely, there could be no doubt. The facts were undisputed, the calculation trivial—the answer awe-inspiring. Far out in the depths of space, a star had exploded with unimaginable violence. Wheeler looked at the figures he had jotted down, checked them for the tenth time, and reached for the phone.

Sid Jamieson was not pleased at the interruption. “Is it really important?” he queried. “I’m in the darkroom, doing some stuff for Old Mole. I’ll have to wait until these plates are washing, anyway.”

“How long will that take?”

“Oh, maybe five minutes. Then I’ve got some more to do.”

“I think this is important. It’ll only take a moment. I’m up in Instrumentation 5.”

Jamieson was still wiping developer from his hands when he arrived. After more than three hundred years, certain aspects of photography were quite unchanged. Wheeler, who thought that everything could be done by electronics, regarded many of his older friend’s activities as survivals from the age of alchemy.

“Well?” said Jamieson, as usual wasting no words.

Wheeler pointed to the punched tape lying on the desk.

“I was doing the routine check of the magnitude integrator. It’s found something.”

“It’s always doing that,” snorted Jamieson. “Every time anyone sneezes in the Observatory, it thinks it’s discovered a new planet.”