He read on and on, only half absorbing what he read. But a man who has reached the status of a Med Ship man in the Interstellar Medical Service hasn't finished learning. He's still away down the ladder of rank. He has plenty of studying ahead of him before he gets very far.

The tape-speaker said, "When the gong sounds, breakout will be five seconds off." It began to ticktock, slowly and deliberately. Calhoun got into the control seat and strapped in. Murgatroyd said peevishly, "Chee!" and went to position underneath the chair. The voice said, "Five—four—three—two—one—"

The little Med Ship came out of overdrive, and instantly its emergency rockets kicked violently and Murgatroyd held desperately fast. Then the rockets went off. There'd been something unguessable nearby—perhaps cometary debris at the extremest outer limit of a highly eccentric orbit. Now there was a starfield and a sun within two light-hours. But if Calhoun had stared, earlier, when there was no sun in sight at all, now he gazed blankly at the spectacle before him.

There was a sun off to starboard. It was a yellow sun—a sol-type star with a barely perceptible disk. There were planets. Calhoun saw immediately one gas-giant near enough to be more than a point, and a sliver of light which was the crescent of another more nearly in line toward the sun. But he gazed at a belt, a band, a ribbon of shining stuff which was starkly out of all reason.

It was a thin curtain of luminosity circling this yellow star. It was not a ring from the breakup of a satellite within Roche's Limit. There were two quite solid planets inside it and nearer to the star. It was a thin, wide, luminous golden ribbon which looked like something that needed a flatiron to smooth it out. It looked something like an incandescent smoke ring. It was not smooth. It had lumps in it. There were corrugations in it. An unimaginable rocket with a flat exhaust could have made it while chasing its tail around the sun. But that couldn't have happened, either.

Calhoun stared for seconds.

"Now," he said, "I've seen everything!" Then he grunted as realization came. "And we're all right, Murgatroyd! It's not our computers that went wrong. Somebody fed them wrong data. We arrived where we aimed for, and there'll be a colonized planet somewhere around."

He unlimbered the electron telescope and began a search. But he couldn't resist a closer look at the ribbon in space. It had exactly the structure of a slightly wabbly wrinkled ribbon without beginning or end. It had to be a complex of solid particles, of course, and an organization of solid particles cannot exist in space without orbital motion. But orbits would smooth out in the course of thousands of revolutions around a primary. This was not smoothed out. It was relatively new.

"It's sodium dust," said Calhoun appreciatively. "Or maybe potassium. Hung out there on purpose. Particles small enough to have terrific surface and reflective power, and big enough not to be pushed out of orbit by light-pressure. Clever, Murgatroyd! At a guess it'll have been put out to take care of the climate on a planet just inside it. Which would be—there! Let's go look!"

He was so absorbed in his admiration that the almost momentary overdrive-hop needed for approach went nearly unnoticed. He even realized—his appreciation increasing—that this cloud of tiny particles accounted for the red-dwarf appearance on one of the plates he'd taken. Light passing through widely dispersed and very small particles turns red. From one position, he'd photographed through this dust cloud.