Since the previous scan twenty years earlier, two stars, a K-type and an M-type three years apart, had changed their emission spectrum completely to nonvisible infrared. For a few brief months the discovery had caused some excited debate among the remnants of the astronomy fraternity about how they could decay into red giants so quickly, and the extraordinary coincidence of two stellar neighbors doing so simultaneously. Then a newly settled planet fifty light-years farther out from Earth reported that the pair were still visible in their original spectrum. Working back across the distance, checking the spectrum at various distances from Earth, allowed astronomers to work out that the change to both stars had occurred over a period of approximately seven or eight years.

Given that amount of time, the nature of the change ceased to become a question of astronomy; stars of that category took a great deal longer to transform into red giants. Their emission hadn’t changed due to any natural stellar process; it was the direct result of technological intervention on the grandest possible scale.

Somebody had built a solid shell around each star. It was a feat whose scale was rivaled only by its time frame. Eight years was astonishingly swift to fabricate such a gigantic structure, and this advanced civilization had apparently built two at the same time. Even so, the concept wasn’t entirely new to the human race.

In the twenty-first century, a physicist named Freeman Dyson had postulated that the artifacts of a technologically advanced civilization would ultimately surround their star in order to utilize all of its energy. Now someone had turned his ancient hypothesis into reality. It was inevitable that the two stars would be formally christened the Dyson Pair.