“Doesn’t it get a trifle—boring—being cooped up for fourteen days?” asked Sadler. No sooner had he spoken the words than he realized that he had probably made a fool of himself. But Molton let him down lightly.

“You’ll see,” he answered. “Day or night, it’s much the same underground. Anyway, you can go out whenever you like. Some people prefer the nighttime; the Earthlight makes them feel romantic.”

The monorail had now reached the apex of its trajectory through the mountains. Both travelers fell silent as the peaks on either side reared to their climax, then began to sink astern. They had burst through the barrier, and were dropping down the much steeper slopes overlooking the Mare Imbrium. As they descended, so the sun which their speed had conjured back from night shrank from a bow to a thread, from a thread to a single point of fire, and winked out of existence. In the last instant of that false sunset, seconds before they sank again into the shadow of the Moon, there was a moment of magic that Sadler would never forget. They were moving along a ridge that the sun had already left, but the track of the monorail, scarcely a meter above it, still caught the last rays. It seemed as if they were rushing along an unsupported ribbon of light, a filament of flame built by sorcery rather than human engineering. Then final darkness fell, and the magic ended. The stars began to creep back into the sky as Sadler’s eyes readapted themselves to the night.

“You were lucky,” said Molton. “I’ve ridden this run a hundred times, but I’ve never seen that. Better come back into the car—they’ll be serving a snack in a minute. Nothing more to see now, anyway.”

That, thought Sadler, was hardly true. The blazing Earth-light, coming back into its own now that the sun was gone, flooded the great plain that the ancient astronomers had so inaccurately christened the Sea of Rains. Compared with the mountains that lay behind, it was not spectacular, yet it was still something to catch the breath.