An Example Of Hard And Soft SF

A planet with one side turned to its sun is imagined by both a hard and a soft sf writer. For Poul Anderson, see Beauty On Ikrananka II.

Before traveling to Venus, CS Lewis' Elwin Ransom speculates about the Venerian environment:

"'If Schiaparelli is right there'd be perpetual day on one side of her and perpetual night on the other?'
"He nodded, musing. 'It'd be a funny frontier,' he said presently. 'Just think of it. You'd come to a country of eternal twilight, getting colder and darker every mile you went. And then presently you wouldn't be able to go farther because there'd be no air. I wonder can you stand in the day, just on the right side of the frontier, and look into the night which you can never reach? And perhaps see a star or two - the only place you could see see them, for of course in the Day-Lands they would never be visible...Of course if they have a scientific civilization they may have diving-suits or things like submarines on wheels for going into the Night.'"
-CS Lewis, Perelandra IN Lewis, The Cosmic Trilogy (London, 1990), pp. 145-348 AT 2, p. 165.

Lewis and Ransom are forgetting that they have just said that the whole of Venus is enclosed in a thick atmosphere so the planet that they imagine with its Day-Lands and Night is not a possible version of Venus. But it is also not a possible planet with air on only one side! Lewis is an imaginative writer but in no way a scientist. Anderson carefully explains that the atmosphere does circulate around Ikrananka.