Then he ran. The desert was like molten iron under his bare feet, and the savage radiation on his back was worse than any overseer's whip. His mind threatened to blank out with each step, but he forced himself on. And slowly, as the distance increased, the sun's pyre sank further and further over the horizon. The heat should still have been enough to kill any normal body in fifteen minutes, but he could endure it. He stumbled on in a trot, guiding himself by the stars that shone in the broken sky toward a section of this world where there had been life and some measure of civilization before. After a few hours, the tongues of flame no longer flared above the horizon, though the brilliant radiance continued. And Hanson found that his strong and nearly indestructible body still had limits. It could not go on without rest forever. He was sobbing with fatigue at every step. He managed to dig a small hollow in the sand before dropping off to sleep. It was a sleep of total exhaustion, lacking even a sense of time. It might have been minutes or hours that he slept, and he had no way of knowing which. With the sun gone and the stars rocking into dizzy new configurations, there was no night or day, nor any way to guess the passage of time. He woke to a roaring wind that sent cutting blasts of sand driving against him. He staggered up and forced himself against it, away from the place where the sun had fallen. Even through the lashing sandstorm, he could see the glow near the horizon. Now a pillar of something that looked like steam but was probably vapor from molten and evaporated rocks was rising upwards, like the mushroom clouds of his own days. It was spreading, apparently just under the phlogiston layer, reflecting back the glare. And the wind was caused by the great rising column of superheated gases over the sun. He staggered on, while the sand gave way slowly to patches of green. With the sun gone and the sky falling into complete shreds, this world was certainly doomed. He'd assumed that the sun of this world must be above the sky, but he'd been wrong; like the other heavenly bodies, it had been embedded inside the shell. He had discovered that the sky material resisted any sudden stroke, but that other matter could be interpenetrated into it, as the stars were. He had even been able to pass his hand and arm completely through the sample. Apparently the sun had passed through the sky in a similar manner. Then why hadn't the shell melted? He had no real answer. The sun must have been moving fast enough so that no single spot became too hot, or else the phlogiston layer somehow dissipated the heat. The cloud of glowing stuff from the rising air column was spreading out now, reflecting the light and heat back to the earth. There was a chance that most of one hemisphere might retain some measure of warmth, then. At least there was still light enough for him to travel safely.