alt=Refer to caption|thumb|Reproduction of diagrams by [[Hal Clement, originally published in his article "Whirligig World", Astounding Science Fiction, June 1953. It has a very high rate of rotation, one day on the planet lasting only eighteen minutes. The surface gravity is very high at 665 times Earth gravity at the poles, but at the equator the effective gravity is only three times Earth's as the rapid rotation produces a significant centrifugal force that counteracts most of the gravitational force.
alt=Refer to caption|thumb|Artist's rendering of Mesklin
Mesklin orbits its star in an elongated ellipse, completing a full revolution in 1,800 Earth-days. The planet is cold, with average temperatures ranging from −50 °C at the closest approach to its star to −180 °C at the furthest point in its orbit. Mesklin is itself orbited by two small moons and has a large ring system. They have four eyes and mandibles. The third of the four serial instalments, in the June 1953 issue, was accompanied by a 13-page article by Clement titled "Whirligig World" describing the planet and the process of creating it in detail. Clement later wrote an additional three fictional works using the planet or its denizens: the sequel novel Star Light (1971; originally serialized in Analog Science Fiction/Science Fact, June–September 1970) and the short stories "Lecture Demonstration" (1973)<!-- Westfahl gives the year as 1974; this is an error, as it was originally published in the anthology Astounding: John W. Campbell Memorial Anthology (1973), see https://archive.org/details/astoundingjohnwc00camp --> and "Under" (2000).