Mesklin

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Mesklin is the name of a fictional supergiant planet created by Hal Clement and used in a number of his hard science fiction stories.

It is distinctive for the interaction of its strong gravity with the centrifugal force due to its fast rotation, originating, according to Clement's original calculations, a gee force gradient, starting at 3 g on the equator, and ending at 665 g on the planet's poles.

1 Overview
2 See also
3 References
4 Notes

[edit] Overview

The planet first appeared in his series of short stories in Astounding Science Fiction (April-July 1953), which were later converted into the novel Mission of Gravity. Other fictional works using the planet or its denizens include "Under", "Lecture Demonstration", and Star Light. The book Heavy Planet is a collection of Mesklin-related works by Hal Clement.

Clement described the basic characteristics of Mesklin in the article "Whirligig World" in Astounding Science Fiction (June 1953). He based the world on an object then thought to exist in the 61 Cygni system, which had been detected by analysis of the motion of the two already known stars in the system.

Unfortunately, further analysis, with more extensive data, led to the conclusion that the find had been erroneous. Had the discovery held up, the object would have been one of the very first extrasolar planets to be discovered, decades before the first flurry of well-established discoveries around the turn of the third millennium.

Hal Clement decided that, since its mass was 16 times that of Jupiter, Mesklin would have an extremely large angular frequency to partly counter its gravity in order to allow humans to visit part of Mesklin. The writer wanted the equatorial gravity to be 3 g, so he determined the period necessary to make this occur: each Mesklin day is 17.75 minutes long given that the planet rotates approximately 20 degrees a minute. As a result of this extremely large rate of spin, Mesklin is not even slightly spherical; it has a large equatorial bulge. Mesklin's equatorial diameter is 48,000 miles (77,250 km), while from pole-to-pole along its axis of rotation it is 19,740 miles (31,770 km). Then Hal Clement attempted to calculate the polar gravity, but this was surprisingly difficult. He admits, "To be perfectly frank, I don't know the exact value of the polar gravity; the planet is so oblate that the usual rule of spheres... would not even be a good approximation..." "Whirligig World" reports his initial calculations of the pole gravity to be 655 g, the paper jacket of Heavy Planet reports the pole gravity as 700 g. A later program created by Clement computed it as 275 g, as did a similar program written by the MIT Science Fiction Society. Clement also gave Mesklin a set of rings and massive moons. The inner moon is 90,000 miles from the planet's center, with a period of 2 hours 8 minutes ^[1].

Clement assumed that Mesklin's orbit around its sun (which he decided would be 61 Cygni A) took 1800 Earth-days, and was highly elliptical: at its closest point the average temperature would be −50 °C, while at the furthest its average temperature would be −180 °C. Since the orbit is eccentric it moves rapidly past its sun at the closest point, so its temperature would be around −170 °C most of the time.

Hal Clement decided that this imaginary world would have native life-forms, that they would be based on methane (CH₄), and that there would be oceans of methane. Unfortunately, methane has a low boiling point, suggesting that Mesklin's sun might boil its oceans and cause the methane to escape the planet entirely. Thus, the writer arranged the planet so that its northern hemisphere's midsummer occurs when it is nearest its sun. Thus, the northern hemisphere would develop a large frozen methane cap during most of its year; the southern hemisphere (where most creatures live) is protected from the sun's closest approach by the rest of the planet. He also asserted that the planet would have a fairly rapid precession.

In "Whirligig World", Hal Clement stated that he gave "official permission to anyone who so desires to lay scenes there [in Mesklin]. I ask only that he maintain reasonable scientific standards, and that's certainly an elastic requirement in the field of science fiction."

Mesklin, "Whirligig World", and the Clement stories based on them are important in science fiction because they illustrated how to carefully incorporate all known (at the time) scientific facts into an interesting setting, which could then be used as a basis to create interesting stories. They were also the first stories set outside the solar system on a planet believed (then) actually to exist.