"You mean—the way the red stars go dim when we drain them of the red rays that power our ships and inter-planet communications?"
"Just that way," said Moore, blinking in excitement.
For a long moment their glances were locked. Then Ross heaved a stifled sigh. "This may mean a lot, Harry," he murmured. "I wonder if it might not even mean—"
"Whatever happened to Number Eight?" asked Moore quickly.
Slowly Ross nodded. "Let's see. Denabola's a blue star. Have you checked on any other blue stars?"
Moore took the seat at the star scope. "Only Vega. She's dim, too. Let me get Sirius." He twirled a knob at the side of the telescope barrel, then another, then straightened, with an explosive gasp. "Look at Sirius!"
Ross looked and caught his breath. Sirius, the brightest star in all the firmament, was a dull lackluster thing.
Flight-Commander Bruce Ross sat back at the star-scope and pushed his space helmet off his head. He ran a steady hand through his unruly blond hair, smoothing out the tight wrinkles in his broad forehead as if to silence the urgent question that hammered in his brain. Something was happening in the heavens, and all his lore of flying and fighting might be none too much to set against the celestial puzzle.
"Harry," he asked finally, "the Moon Men know all about our red-ray work. Do you suppose they've gone to work somehow on the blue stars?"
Moore screwed up his face, blinking behind his glasses. "Well," he said finally, "there's Horta."