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Mesklin | |
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First appearance | Mission of Gravity (1953 ) |
Created by | Hal Clement |
In-universe information | |
Type | Supergiant planet |
Mesklin is 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 gradient in the perceived force of gravity from 3 g on the equator to 665 g on the planet's poles.
Mesklin is a planet in the 61 Cygni binary star system.[1] Its mass is sixteen times that of Jupiter, or 4,800 times Earth mass.[2][3] It has a very high rate of rotation, one day on the planet lasting only eighteen minutes.[1] As a result, the planet is significantly flattened with a large equatorial bulge: the diameter at the equator is 48,000 miles (77,000 km) while the diameter between the poles is slightly below 20,000 miles (32,000 km); the diameter of Earth, for comparison, is roughly 8,000 miles (13,000 km).[1][2][4] The planet thus has a significantly higher mass than Jupiter within a much smaller volume, and its core is made up of collapsed matter.[2][5] The surface gravity is very high at 665 times Earth gravity at the poles, but the rapid rotation produces a significant centrifugal force that cancels most of this at the equator, resulting in a net gravity at three times Earth gravity there.[6]
Mesklin is orbited by two small moons and a large ring system.[3][4] The planet's orbit around its star has a high orbital eccentricity.[7]: 87
The planet first appeared Hal Clement's novel Mission of Gravity (1954), which was first serialized in Astounding Science Fiction (April–July 1953);[8] in the June 1953 issue, alongside the third of the four serial instalments, was included a 13-page article by Clement titled "Whirligig World" describing the planet in detail.[3][9] 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" (1974) and "Under" (2000).[8][10] The book Heavy Planet (2002) is a collection of these five Mesklin-related works.[11][12]
In "Whirligig World", Clement encouraged other authors to use Mesklin as a setting for their stories provided that they stay within "reasonable scientific standards", while acknowledging that to be "certainly an elastic requirement in the field of science fiction".[13]: 107 [14]
Clement 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.[7]: 87 [15] Further analysis with more extensive data led to the conclusion that the find had been erroneous.[16] Clement used what was thought to be known about the object, dubbed 61 Cygni C by astronomers, and tried to create an interesting setting for a story within those bounds.[15]
The observed mass of the object, at approximately 16 Jupiter-masses, meant that it was expected to be somewhat smaller than Uranus as a result of gravitational compression.[17] At the time, it was unknown whether such an object would behave more like a very low-mass and faint star (a brown dwarf) or a high-mass planet (Super-Jupiter); Clement elected to depict Mesklin as the latter in order to be able to use it as a setting for his story.[17] Given this size and mass, the surface gravity would be about 300 times Earth gravity (300 g).[17][18]: 35
Clement decided that Mesklin would have an extremely large angular frequency to partly counter its gravity in order to allow humans to visit part of it. He 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 Clement attempted to calculate the polar gravity, finding it 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..."[18]: 35 [13]: 108 "Whirligig World" reports his initial calculations of the pole gravity to be 655 g; the dust jacket of Heavy Planet reports it 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. The MIT group also concluded that the planet would have had a sharp edge at the equator.[19]
Clement assumed Mesklin's orbit around its star (which he decided would be 61 Cygni A) took 1,800 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.
Clement decided this imaginary world would have native life-forms, that they would be based on methane (CH4), and there would be oceans of methane. However, 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 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 the planet would have a fairly rapid precession.
Clement noted that several of his story ideas resulted from a personal tendency to react contrarily to certain "common sense" assertions, which had the nature of "of course": [some situation] has [some certain characteristic], but of course it cannot have [some other characteristic]. The notion of Mesklin's odd configuration stemmed from the fact that there were science fiction stories that featured low-gravity planets and high-gravity planets, but of course no single planet could have both low and high gravity.[20]
In short, to avoid a much longer list, it is safe to say that nearly everything about the planet Mesklin is not only scientifically valid, but also carefully extrapolated from known data and theory. Mesklin was constructed by Clement through a process something like this: If A is postulated, then current scientific knowledge and theory states that B, C, D, and so on either must follow or can logically and validly follow.
L. David Allen, 1973[21]: 107
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) to actually exist.[22]: 170
Stephen L. Gillett , writing in The Greenwood Encyclopedia of Science Fiction and Fantasy (2005), described Mesklin as the prototypical example of an alien world vastly dissimilar to Earth,[23] while Gary Westfahl, in Science Fiction Literature through History: An Encyclopedia (2021), commented that Mission of Gravity and "Whirligig World" together "effectively launched" the hard science fiction subgenre a few years before the term was even coined.[10] Westfahl, writing in 1996, also argued that Mesklin itself may be considered the main character of Mission of Gravity.[24]: 86 Basil Davenport, writing in 1955, commented that the only aspect not in line with current scientific knowledge was that humans had sent a spaceship to the planet;[18]: 36 L. David Allen , writing in 1973, similarly called this level of human spaceflight "one of the few imaginary science details".[21]: 105
Mission of Gravity is noteworthy not only as an impressive piece of planet-building, but as the first SF novel built on actual observational data involving another possible solar system