Rama showed no such changes. Either it was not spinning at all or it was perfectly symmetrical. Both explanations seemed equally unlikely.

There the matter rested for several months, because none of the big orbiting telescopes could be spared from their regular job of peering into the remote depths of the universe. Space astronomy was an expensive hobby, and time on a large instrument could easily cost a thousand dollars a minute. Dr. William Stenton would never have been able to grab the Farside two-hundred-metre reflector for a full quarter of an hour, if a more important programme had not been temporarily derailed by the failure of a fifty cent capacitor. One astronomer’s bad luck was his good fortune.

Bill Stenton did not know what he had caught until the next day, when he was able to get computer time to process his results. Even when they were finally flashed on his display screen, it took him several minutes to understand what they meant.

The sunlight reflected from Rama was not, after all, absolutely constant in its intensity. There was a very small variation—hard to detect, but quite unmistakable, and extremely regular. Like all the other asteroids, Rama was indeed spinning. But whereas the normal “day” for an asteroid was several hours, Rama’s was only four minutes.

Dr. Stenton did some quick calculations, and found it hard to believe the results. At its equator, this tiny world must be spinning at more than a thousand kilometres an hour; it would be rather unhealthy to attempt a landing anywhere except at the poles. The centrifugal force at Rama’s equator must be powerful enough to flick any loose objects away from it at an acceleration of almost one gravity. Rama was a rolling stone that could never have gathered any cosmic moss; it was surprising that such a body had managed to hold itself together, and had not long ago shattered into a million fragments.