Saturday, 21 April 2012

Unusual Heavenly Bodies

In Poul Anderson's History of Technic Civilization:

Planets
Jupiter has solid land masses because that was a reasonable assumption when Anderson wrote about it.
Diomedes' poles are in the ecliptic plane. Each spends half the year in winter and night. Intelligent Diomedeans are winged migrators.
Although the planet Woden has two and a half Terran gravities, its sun is so energetic that Wodenite life can grow massive.
Tidal action has forced one hemisphere of the small, eccentrically orbiting, librating planet Ikrananka to face its red dwarf sun but such slow rotation generates a weak magnetic field so that the planet retains an atmosphere although most of its water has frozen on the cold side making the warm side a slowly deteriorating desert whose inhabitants, struggling for survival in their season-less, rhythm-less environment, regard nature as hostile, believing in demons but not in gods, whereas dwellers on the edge of the Twilight Zone with rain, snow, day, night and constellations, more conventionally believe in an annually dying and rising god and a single devil whose power can be neutralized. The latter are easier to trade with.
Pressure and temperature gradients on Daedalus refract light around the curve of the planet so that there is no horizon. Sunset is a ring of fire.
Nike is very small but holds an atmosphere and biosphere because it is so old that its weak gravity has had enough time to pull heavier elements into an atmosphere-generating solid core. Age explains its sun's variability which adversely affects Nikean weather.


Giant Stars and Rogue Planets
The red giant Betelgeuse has planets, some of them with life, because that was a reasonable assumption when Anderson wrote about it.
David Falkayn brags of finding a rogue (sunless) planet between Tau Ceti and 70 Ophiuchi although this adventure really happened to someone else.
The Merseians keep a base on Vorida, a rogue planet in the Betelgeuse sector.
The rogue planet Satan bypassing the blue giant Beta Crucis in a hyperbolic orbit becomes a base for the industrially valuable transformation of elements into heavier isotopes when its cryosphere becomes atmosphere and hydrosphere, coolants for heat waste.
A condensing giant star's gravity prevents the condensation of planets but nebular friction around the condensing blue giant Beta Centauri converted the hyperbolic orbits of a cluster of passing rogue planets into eccentric elliptical orbits.
A rogue planet hitting the star Saxo causes it to explode destroying its planets, including the inhabited Starkad.


Giant Planets and Eccentric Orbits
The captured planets of the blue giant Beta Centauri have eccentric orbits. See above.
Another star passing near Siekh skews its planets' orbits. The planet Talwin's distance from Siekh varies from 0.87 to 2.62 astronomical units. Huge ice caps form and melt each twice Terran year. There are floods and rain storms. One intelligent race hibernates in caves. Another estivates at sea. They do not meet.
In the Cerulian system, resonance with the jovoid planet Ogre has multiplied perturbation and brought the eccentricity of the terrestroid Vixen's orbit close to one-half so that, with a 24 degree axial tilt and midsummer nearly at periastron, once every eighteen month year the northern hemisphere is scorched with four times the radiation that Terra receives from Sol - snow melts, rivers overflow, lakes bake dry, storms rage, fires break out, erosion prevents mountain formation, hot wind blows dust and ash across dry plains.
A subjovian planet, which lost most of its lighter gasses when an eccentrically orbiting moon crashed on it, now has 15 Terran masses concentrated in a solid globe called Paradox but 8% of its atmosphere remains helium which diffuses through any material, ruining unprotected equipment.
The Cloud Universe globular cluster's eccentric orbit passes through dense clouds near the galactic centre, gathering gas and dust which condense into heavy-metal-rich stars and planets.


Supernovae
When a superjovian planet of 1500 terrestrial masses orbits a star that goes supernova, the planetary core, now called Mirkheim, survives coated in valuable supermetals which are impossibly expensive to synthesise.
The massive star Valenderay, older than normal for its type in its region, must have come from elsewhere. Its supernova explosion will cause ecological disaster on the planet Merseia a parsec away unless artificial force screens protect the planet.
A nearby supernova causes a superjovian planet of 3000 Terrestrial masses to lose all its hydrogen and helium, over 90% of its mass, transforming it into Ramnu, a glacial globe of 310 Terrestrial masses, later inhabited by small, intelligent gliders.
A peak of radiation from the planet Dathyna's massive, metal-rich, irregularly variable sun, which probably condensed near a recent supernova, destroyed civilisation but produced a killer mutation which exterminated the parent race, appropriated its technology and now threatens the Polesotechnic League.
Periodic ingestion of new matter by the Cloud Universe (see above) causes several supernovae per century for at least a million years.


Notes on the Above

Falkayn spells out why Satan alone is ideal for producing heavier isotopes. This cannot be done:

on inhabited planets because heat and radioactive waste would make them uninhabitable;
on uninhabited planets because heat waste added to solar radiation would vaporise the rivers needed for coolants;
on uninhabited planets with orbiting albedo-raising dust clouds because these would trap home-grown heat;
in newly formed systems because factories would be bombarded by meteors and asteroids;
on airless planets because the necessary heat exchangers are expensive and put engineering limits on the size of a plant;
on Jovoid planets because free hydrogen diffuses through materials and interferes with nuclear reactions;
on ordinary rogue planets because temperatures near absolute zero affect the properties of matter and because liquid water and gaseous atmosphere are necessary coolants.

 
Anderson invented several ways to disrupt familiar celestial processes:

a giant star capturing rogue planets;
a supernova transforming one of its own planets into the industrially valuable Mirkheim;
a supernova potentially devastating a planet in a nearby system;
a supernova transforming a planet in a nearby system into the massive but solid Ramnu;
a supernova affecting the condensation of another star;
a rogue planet causing a nova by hitting a star;
a rogue planet becoming the industrially valuable Satan by just missing a star;
a star causing eccentric planetary orbits by just missing another star;
an eccentrically orbiting moon transforming its planet into the massive but solid Paradox by hitting it;
an eccentrically orbiting globular cluster causing new stellar condensations and novae by gathering dust from clouds near the galactic center;
planets with eccentric axial tilts;
a planet with no horizon;
a planet with a very close horizon!


Unscientific readers forget technical details so it is good to summarize them. The explanations begin to sound similar but, in each case, they are used to create a unique effect. Supernovae:

usually destroy all their own planets;
can affect planets in nearby systems;
possibly affected the condensation of a nearby star. 

 
In "A Sun Invisible," Anderson planned to introduce the unexpected Beta Centaurian system as the solution of a puzzle so he had Falkayn mention rogue planets earlier in the story. Thus, it was not a deus ex machina when captured rogues turned out to explain why there are planets orbiting a giant star. In Ensign Flandry, Anderson introduced the planet Starkad only to reveal, near the end of the novel, that its sun was doomed to be hit by a rogue planet so, again, Anderson made sure that a rogue, Vorida, had been mentioned much earlier in the novel.
 
These features recur:
 
giant stars;
superjovian planets;
novae and supernovae;
industrially valuable planets;
massive but solid planets;
stellar and planetary condensations;
metal-rich stars and planets;
rogue planets;
collisions;
near misses;
eccentric orbits;
other odd planets;
intelligent fliers or gliders.
Responding to these phenomena, Anderson's characters:
negotiate with Ikranankans and Betelgeuseans;
let extra-solar hydrogen-breathers who have colonised Ogre colonize Jupiter;
colonise the Beta Centaurian system;
trade with Diomedeans;
save Merseia;
incorporate Wodenites and Dathynans;
evacuate some Starkadians;
exploit Satan, Mirkheim and the Cloud Universe;
study Talwin, Ramnu and Paradox;
live on Kirkasant (in the Cloud Universe), Vixen, Daedalus and Nike.

Added on 12/5/12: A revised text explains that the Betelguesean planets were seeded and colonized but should they have existed? 

Added, 23/5/12: Data on Diomedes that I missed above: the system is metal-poor though not old possibly because the electromagnetic action of a passing neutron star fractionalized the original cloud of dust and gas. Consequently, Diomedes has 4.75 terrestrial mass but a low density so its gravity is only 1.10.

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