In the essay "Whirligig World" at the back of Hal Clement's Mission of Gravity (about how the planet Mesklin was invented for the book) he states that he thought of titling the book Pancake in the Sky, "but Isaac Asimov threatened violence".

What does this mean?

  • 7
    I guess it would be the similarity of the title to Asimov's novel "Pebble in the Sky" Commented Feb 19, 2021 at 11:16
  • 1
    Not to mention, combined with that, the pun on the shape of Mesklin. After all, Asimov isn't on record as having threatened Heinlein over Tunnel In the Sky.
    – Zeiss Ikon
    Commented Feb 19, 2021 at 12:26
  • 3
    These two answers: the shape of Mesklin (which was highly oblate) and the pun on Asimov's recent title (1950 for Pebble, 1953 for Mission of Gravity) explain it perfectly. One of you should make this an answer.
    – Mark Olson
    Commented Feb 19, 2021 at 14:20

1 Answer 1


The planet Mesklin, the setting for Mission of Gravity, is a highly oblate spheroid, with an equatorial diameter of 48,000 miles, and a pole-pole distance of about 20,000 miles. In the essay Clement mentions "The model I have of it is six inches in diameter and not quite two and a half thick", so calling it a pancake planet is certainly justified.

Clement was clearly on good terms with Asimov; later in the essay he described how they spent an evening together debating what the major liquid phase on the planet would be, eventually settling on methane. Between friends a bit of teasing is not unexpected, and the joke title "Pancake in the Sky" is clearly intended to echo the title of Asimov's novel "Pebble in the Sky", published four years earlier in 1950.

  • Yes, they knew each other well. They both lived in Boston and Asimov was just two years older than Clement.
    – Mark Olson
    Commented Feb 19, 2021 at 15:30
  • @MarkOlson interesting! Commented Feb 20, 2021 at 2:38

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