Dante, a tidally locked habitable world

Image from Steve Bowers
The Lumiere arrives, battered and worn, at Dante in 1380 a.t.

(this snapshot taken from a ship remote is part of the superb collection maintained by the Dantepolis Virachives Historical Society)

Dante - Data Panel

System:HIP 85647
Primary:HIP 85647
Stellar Class:M0 v red dwarf
Luminosity:0.03 x Sol
Region:Inner Sphere
Planets:a) Dante vesperian class tidally locked (with indigenous biosphere)
diameter 14,809 km
gravity 0.9gee
orbit 0.2 a.u.
period 51 days

b) Beatrice jovian class
diameter 110,000km
orbit 3.2 Au

Xenobiology and Xenecology

The world of Dante was colonised in 1380 a.t. by the Company of Venturers from Nova Terra in the relativistic ship Lumiere, one of the first colonisation efforts by the Novans.

Despite the fact this world is tidally locked to the red dwarf star HIP 85647 an earth-like alien biosphere had developed in the zone between the hot day-side and the cold nightside; the slow rotation of Dante as it orbits the sun is enough to maintain a circulation in the atmosphere from west to east. It is apparent from the fossil record that life developed on this world more than two billion years ago, when the world was not yet tidally locked.

Because Dante remains oriented towards the local star, the easternmost and westernmost points of the terminator have distinct climates, and are known as the 'east and west poles'. The low-level airflows are darkward at both east and west poles and return over the north and south poles, while the very high-level circulation forms a superrotating jet stream around the planet.

Air moving over ice from the cold hemisphere at the north and south poles towards the warm hemisphere becomes warmer (both due to entering the warmer hemisphere, and because the air descends from the icecap and is heated by compression). This means the air at the north and south poles where the dark-to-light return flow occurs is not moist enough for rain. The air does however cool enough to allow precipitation where the hot (but not completely dehydrated) air returns from light to dark, at both the east and west poles.

As on Twilight and other vesperian worlds, surface winds are quite high in many habitable regions, so wind sports of various kinds are popular.

Dante's aboriginal biology has developed quite differently in the two habitable zones, which are separated by dry regions of tundra/savanna at the poles. The West has dark brown and purple coloured rain forests, adapted to catch the infrequent thermal driven rainstorms; the east has low-lying moss-like scrub, adapted to exploit the near-constant drizzle and the glacier melt water. Animal-like sessile land anemones catch the numerous flying insect-like thirps, while larger ground thirps patrol the leaf litter layer.

Due to the distribution of wavelengths in the sunlight from the red dwarf sun, the vegetation seems dark, almost to the point of blackness; however in artificial white light the green tint of many of the plant-like species is apparent. In fact the biochemistry of Dante aboriginal life is quite similar to that of Earth; chlorophyll is assisted by a wide range of accessory pigments including phytocyanin and allophytocyanin to absorb red and infrared light; the genetic material of the biosphere is a mixture of zDNA and twin strand RNA, not far different from Earthly nucleic acids. This has allowed the human population of Dante to exploit the local biosphere for food with relatively little genetic modification to themselves and to their food crops, and giant thirp hunting is a favourite pastime on this world.


The two habitable zones are both very limited in size, and population pressure was soon a problem. The single gas giant Beatrice offered limited opportunity for off-world migration, and by 3500 a.t this giant world was encircled by several thousand rotating habitats under the watchful eye of the local power, DaCapo. By contrast the human population on Dante, a self-sustaining Vesperian Gaian world, did not need or desire transapient oversight. The two habitable segments of Dante continued to develop independently of the Beatrice habitat fleet and of each other.

By 4210 the archanarchists of the Western habitable zone were at loggerheads with the Etodist faithful of the soggy east; over and again the hemispheres fought against each other in the hot dry desert of Sunward and the icy black wastes of Nightward.

Long after the Version war, during which Dante was placed under Solarist occupation but Beatrice remained a free independent zone, the hemispheres remained bitter rivals and opponents.

When at last the importation of the Virsurroundings memetic complex in the 7700's provided a partial solution to the problems of crowding on this world, the ancient feuds became largely history and paradoxically a subject for nostalgia.


This technology allows nearbaseline humans and other clades to choose the appearance and dimensions of their surroundings, using a combination of direct neural interface and utility fog environment simulation. Even when meeting face to face two people using Virsurrounding tech will perceive their worlds, and each other, in totally different ways. In this way the people of Dante have become more diverse, and less prone to sectarian politics; they are also able to have a rich and varied lifestyle in comparatively little physical space.

Terraforming Schemes

There have been many proposals for the terraforming of this crowded world, involving the melting of the ice on the dark side and the cultivation of the dry side; these have ranged from relatively simple sunshade and mirror schemes to plans for an artificial rotation to be imparted to the planet. Most of the artificial rotation schemes were judged to be too disruptive by the world council, while the sunshade and mirror and other illumination schemes have been indefinitely shelved since the introduction of the virtual surrounding technology.

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Development Notes
Text by Steve Bowers
Amendments suggested by Brian Davis
Initially published on 04 August 2004.