The Wonderful Flight to the Mushroom Planet books that I enjoyed as a kid, and am passing down to my kids. I remembered reading a lot of science fiction pitched at kids when I was growing up. This was before I discovered Ray Bradbury and the Martian Chronicles and moved into "grown up" sci fi. But anyway, I had only vague recollections of what that early science fiction was--lots about space cadets and such. Then I remembered that many were by Robert A. Heinlein, so that started a search for these. He wrote a whole series of books for Scribner's for what were then called juveniles and are now called "Young Adults." Orphans of the Sky, pictured above, actually is not one of them.
In reading through the detailed summaries of Heinlein's juvenile books (on wikipedia), none really rang a bell. But I remembered a book that took place on a ship on a long voyage--so long that the passengers forgot that they were on a voyage or even on a ship; the ship was the world. The gravity was near zero by the outer decks, but full gravity in the inner levels where farms were. I recalled the differences in gravity, and a scene where a character stares out at the stars for the first time. That's all I remembered. Turns out, it was Orphans of the Sky.
So I ordered a copy (first edition, ex library, pictured above) and am about halfway through--a breezy read, very much of its era (1940s and 1950s; the book is actually two novellas, previously published, that were published as one volume under this title in the early 1960s). I actually seem to recall very little of the story itself (how could I have forgotten the guy with two heads!).
And soon, on to collect the other early Heinleins. Rocket Ship Galileo, Podkayne of Mars...
[I should point out that I'm not recommending this book for children; at the very least because of how it treats women (terribly)]
3 days ago