Mesklin

Mesklin is a fictional planet created by Hal Clement and used in a number of his hard science fiction stories, starting with Mission of Gravity (1954). Alongside the novel's original 1953 serialization in Astounding Science Fiction, Clement published an essay titled "Whirligig World" on how he designed the planet to have the properties he wanted. The idea came from an object that was at the time believed to exist in the 61 Cygni system, and which might represent an extrasolar planet.