Reminds me...
Hal Clement's classic 1954 book: A Mission of Gravity".
Set on a large planet spinning so fast it flattens out to look like an old style spinning top (days take minutes), such that the surface gravity varies hugely with latitude, which itself has all sorts of interesting consequences (eg, the sky+horizon looking inverted, bowl-shaped).
Recommended! A great hard-sf classic.
Biting the hand that feeds IT
