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From orbit.

Chiron, also called Planet, is the setting of Alpha Centauri and its expansion.

Overview[edit | edit source]

Planet is quite a bit more massive than Earth, with a larger radius. While the larger radius reduces the effects of gravity a certain amount, Planet’s greater mass still creates a 30% greater gravitational pull — objects are 30% heavier on Planet than on Earth. Planet is a bit farther from Alpha Centauri A than Earth is from the Sun, but Alpha Centauri A is brighter than the Sun, and these differences offset, so that Alpha Centauri A is almost exactly as bright from Planet as the Sun is from Earth.

Planet’s days are only about 18 hours, so sleep cycles must be correspondingly reduced. Its years are slightly longer than Earth’s years., but not enough to make a noticeable difference. The greater difference is Planet’s lack of seasons. With only a slight axial tilt, any seasonal differences are minimal. Neither of Planet’s moons exert as much tidal pull as Earth’s moon, but when they combine, tides will run slightly higher than on Earth. Once every 80 years, as Alpha Centauri B reaches perihelion (its closest approach to Alpha Centauri A), it generates enough heat to increase Planet’s average temperature by 0.3° C. That doesn’t seem like much, but Planet’s climactic system might easily amplify this to uncomfortable levels. In fact, any life native to Planet may have evolved cyclic responses to this event.

The atmosphere consists of 90.9% Nitrogen, 8.5% Oxygen and .01% Carbon Dioxide. The low oxygen content results in fewer forest fires, a higher proportion of anoxic (oxygen-free) environments — encouraging a large anaerobic ecosystem reducing nitrates to break down organic matter — and a plant ecosystem dominated by the need to conserve carbon.

Meteorology and climatology[edit | edit source]

A composite map of Planet's surface.

Planet’s larger size and gravity result in a significantly higher sea level pressure than Earth’s: 1.74 atmospheres (that is, 74% greater air pressure at sea level than on Earth). This brings the partial pressure of Oxygen (15k Pascals) up to acceptable levels, but the high overall pressure combined with such a large quantity of Nitrogen produces deadly Nitrogen narcosis in unprotected humans. Human colonists would have to wear pressure helmets, at the very least. The temperature bands running along the surface of Planet are the most obvious climactic pattern. As on Earth, solar energy warms the equatorial areas, and the weather cools as you migrate towards the poles. Thus, equatorial regions produce more energy, while the poles tend to have more mineral resources.

The rainfall patterns of Planet depend on the wind currents, which always blow from west to east. Since the wind carries moisture with it from the oceans, rain tends to fall on the west side of mountain ranges. You can see this trend when looking at a big continent — green predominates on the western coast, indicating a great deal of rainy or moist terrain, while the east coast remains dry and barren. Rainfall determines the amount of nutrients that may be collected, so often the west coast of a continent proves a better source of nutrients than the east coast. On flat continents or small islands, no elevations exist to trap the rainfall, and so moisture tends to be more evenly distributed. Also, river valleys usually have a reasonable amount of rain, so a river running through a dry area can be a good base location.

The warm tropical seas of Planet are breeding grounds for hurricanes, which are also encouraged by the high gravity and rapid rotation. The dense nitro- gen atmosphere only partly offsets this. The equatorial cloud belts, however, help to regulate the climate by reflecting sunlight.

At over 20% higher insolation than Earth, Planet has very small polar ice caps. The effect of this on the oceanic circulation is profound. Instead of cold oxygen-rich polar water sinking at the poles and being carried in a current along the ocean floor to the equator (as on Earth today), the circulation is driven in reverse, with warm saline oxygen-poor water sinking at the equator and flowing to the poles. As a result, the bottom waters have little oxygen.

Soil composition[edit | edit source]

Compared to Earth, silicates are much less common in the soils of Planet. As in the tropics on Earth, warm water leaches the silica from clays, leaving a poor alumina-rich soil. (This does not prevent rain forests from growing, but will inhibit agriculture.) The arctic regions have a higher proportion of acidic soils with a high proportion of organic matter (podzols) which is equally hard to farm. The temperate soil zone, which on Earth is favoured with rich alumi- nosilicate clays, is much narrower on Planet, and the soils are more likely to be sandy or lime-rich. Bogs are also common.

Ecology[edit | edit source]

Although basically similar to Earth life, in that it is based on carbon compounds in water, the organisms of Planet have evolved a biochemistry very different from Earth. The scarcity of carbon in the environment, and of dioxygen in the soil, has forced plants to try to make do without O2 (oxygen), and to economize on the use of carbon in structural parts and as an energy storage material. They do this by using a biochemical reaction unknown on Earth. Planet’s plants seem to have a special enzyme to encourage this reaction, possibly with the aid of sunlight. They use the nitrate obtained this way to store energy as organic nitro-compounds, to reduce carbonates to carbon, and to carry out respiration in anoxic environments.

The prevalence of anoxic (oxygen-free) environments rich in organic material, combined with the presence everywhere on Planet of nitrated compounds, has led to an astonishing variety of underground organisms which live in the absence of oxygen (though they can use oxygen if it is present) and “breathe” nitrate. This ecosystem apparently has symbiotic relations with the plants and with Planet’s animal life. Also note that the prevalence of nitrate in the environment has serious repercussions.

Nitrous oxide is present in only small amounts as it combines with ozone in the stratosphere to break down into N2 and O2 (which prevents the build-up of an ozone layer). When plant material is buried, nitro-hydrocarbons have all they need to “burn,” so they do so slowly underground, leaving nothing behind until all the reducing material (hydrocarbon) or all the oxidizing material (nitrate) has gone. Nitrate nearly always runs out first, leaving a residue of carbon compounds. Provided this does not come into contact with oxygen, it fossilizes to produce ordinary fossil fuels. Since Planet has been hot and hypoxic for a long time, it should be expected to have all the oil, shale and coal anyone could want, depending on the efficiency of the ecosystem. Regardless of any attempt to wipe out the underground nitrate respirers, all efforts to return carbon to the biosphere would encourage Planet life to proliferate.

Conversely, the huge quantities of nitrate in the soil would be heaven to human farmers. However, water would have to be treated in order to remove the nitrates so that it is safe to drink; otherwise humans would suffer from methhemoglobinemia, or “blue baby syndrome,” where the red blood cells are poisoned so they can’t take up oxygen. The best way to treat this water is to pass ozone through it to destroy the nitrate.

Landmarks[edit | edit source]

Landmarks are giant natural wonders of Planet, the most important geophysical features of the world. You might encounter any of the following.

  • Freshwater Sea. The richest aquatic region on Planet provides +1 nutrient per square.
  • Garland Crater. Some thousands of years ago, a massive object crashed into Planet, leaving this vast crater. The rare and valuable remnants of the original object remain in the crater, giving the squares inside a +1 mineral bonus.
  • Geothermal Shallows. A whole field of underwater geysers underlies this coastal shelf, providing +1 energy per square.
  • Great Dunes. The largest, most unforgiving desert on Planet. The Great Dunes provide no bonus resources, and are in fact a remarkably inhospitable place.
  • Monsoon Jungle. This is an anomalous expanse of thick and curiously earthlike vegetation. The rich soil of the Monsoon Jungle yields +1 nutrient per square.
  • Mount Planet. This enormous volcano is active, but its slopes provide a +1 bonus of both minerals and energy. The enormous crater at the top fills a whole square with lava.
  • New Sargasso. This is the largest naturally occurring growth of sea fungus on Planet. It provides no special bonus, other than the resources that can be harvested from the fungus itself.
  • Pholus Ridge. The geothermal energy unleashed by the clash of two of Planet’s tectonic plates produces +1 energy per square along Pholus Ridge.
  • Sunny Mesa. This extensive highland offers no special resource bonuses, but its elevation makes it naturally excellent for harvesting energy.
  • The Ruins. A vast and ancient ring of monoliths embedded in thick xenofungus, it has no special resources, other than the monoliths themselves.
  • Uranium Flats. This savanna is particularly rich in heavy elements that provide +1 energy per square.
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