James Blish - A Case of Conscience

The Planet Lithia (from Michelis, D., and Ruiz-Sanchez, R.: Lithia — a preliminary report. J. I. R. 4:225, 2050; abstract.) Lithia is the second planet of the solar type star Alpha Arietis, which is located in the constellation Aries and is approximately 50 light-years from Sol. [1]

It revolves around its primary at a mean distance of 108,600,000 miles, with a year of approximately 380 terrestrial days. The orbit is definitely elliptical, with an eccentricity of 0.51, so that the long axis of the ellipse is approximately 15 per cent longer than the short axis.

The axis of the planet is essentially perpendicular to the orbit, and the planet rotates on its axis with a day of about 20 terrestrial, hours. Hence, the Lithian year consists of 456 Lithian days. The eccentricity of the orbit produces mild seasons, with long, relatively cold winters, and short, hot summers.

The planet has one moon with a diameter of 1,256 miles, which revolves about its primary at a distance of 326,000 miles, twelve times in the Lithian year.

The outer planets of the system have not yet been explored. Lithia is 8,267 miles in diameter, and has a surface gravity of 0.82 that of Earth. The light gravity of the planet is accounted for by the relatively low density, which in turn is the result of its composition. When the planet was formed there was a much lower percentage of the heavy elements with atomic numbers above 20 included in its make-up than was the case with the Earth. Furthermore, the odd-numbered elements are even rarer than they are on Earth; the only odd-numbered elements that appear in any quantity are hydrogen, nitrogen, sodium and chlorine. Potassium is quite rare, and the heavy odd-numbered elements (gold, silver, copper) appear only in microscopic quantities and never in the elemental form. In fact, the only uncombined metal that has ever appeared on the planet has been the nickel-iron of an occasional meteorite. The metallic core of the planet is considerably smaller than that of the Earth, and the basaltic inner coating correspondingly thicker. The continents are built, as on Earth, basically of granite, overlaid with sedimentary deposits.

[1. An earlier figure of 40 light-years, often quoted in the literature, arose from application of the so-called Cosmological Constant. Einstein's reluctance to allow this “constant” into his scholium has now been fully justified, v. Haertel, J. I. R. 1:21, 2047]

The scarcity of potassium has led to an extremely static geology. The natural radioactivity of K40 is the major source of the internal heat of the Earth, and Lithia has less than a tenth of the K40 content of the Earth. As a result, the interior of the planet is much cooler, vulcanism is extremely rare, and geological revolutions even rarer. The planet seems to have settled down early in life, and nothing very startling has happened since. The major part of its uneventful geological history is at best conjectural, because the scarcity of radioactive elements has led to great difficulties in dating the strata.

The atmosphere is somewhat similar to that of the Earth. [2] The atmospheric pressure is 815.3 mm at sea level, and the composition of dry air is as follows:

Nitrogen 66.26 per cent by volume Oxygen 31.27 Argon, c. 2.16 CO 20.31

The relatively high CO 2concentration (partial pressure about 11 times that of the gas in the Earth's atmosphere) leads to a hothouse type of climate, with relatively slight temperature differences from pole to equator. The average summer temperature at the pole is about 30° C., at the equator near 38° C., while the winter temperatures are about 15° colder. The humidity is generally high and there is a lot of haze; gentle, drizzling rain is chronic. There has been little change in the climate of the planet for about 700 million years.

Since there is little vulcanism, the CO 2content of the air does not rise appreciably from that cause, and the amount consumed in photosynthesis by the lush vegetation is compensated for by the rapid oxidation of dead vegetable matter induced by the high temperature, high humidity, and high oxygen content of the air. In fact, the climate of the planet has been in equilibrium for more than half a billion years. As has the geography of the planet. There are three continents, of which the largest is the southern continent, extending roughly from latitude 15° south to 60° south, and two-thirds of the way around the planet. The two northern continents are squarish in shape, and of sizes similar to each other. They extend from about 10° south to about 70° north, and each one about 80° east and west. One is located north of the eastern end of the southern continent, the other north of the western end. On the other side of the world there is an archipelago of large islands, the size of England and Ireland , running from 20° north to 10° south of the equator. There are thus five seas or oceans: the two polar seas; the equatorial sea separating the southern from the northern continents; the central sea between the two latter, “ and connecting the equatorial sea with the north polar sea; and the great sea, stretching from pole to pole, broken only by the archipelago, extending a third of the way around the planet.

The southern continent has one low mountain range (highest peak 2263 meters) paralleling its southern shore, and moderating the never very momentous effect of the south winds. The northwestern continent has two ranges, one paralleling the eastern and one the western sea, so that the polar winds have a free run, and give this continent a more variable climate than that of the southern one. The northeastern continent has a slight range along its southern shore. The islands of the archipelago have few hills, and possess an oceanic type of climate. The trade winds are much like those of Earth, but of lesser velocity, due to the lesser temperature differentials between the different parts of the planet. The equatorial sea is nearly windless.

Except for the few mountain ranges, the terrain of the continents is rather flat, particularly near the coasts, and the lower reaches of all the rivers are of the meandering type, bordered with marshes, and with low plains that are flooded, miles wide, every spring.

There are tides, milder than on Earth, producing an appreciable tidal current in the equatorial sea. As the coastal terrain is generally quite flat, except where the mountain ranges come to the sea, wide tidal flats separate the shore from the open sea. The water is similar to that of earth, but considerably less salty. Life began in the sea, and evolved much as it did on Earth. There is a rich assortment of microscopic sea life, types resembling such forms as seaweed and sponges, and many Crustacea and mollusklike forms. The latter are very highly developed and diversified, particularly the mobile types. Quite familiar fishlike forms have emerged and dominate the seas as they do on Earth.

Present-day Lithian land plant life would be unfamiliar, but not surprising, to a terrestrial observer. There are no plants exactly like those of earth, but most of them have a noticeable similarity to those with which the visitor would be familiar. The most surprising aspect is that the forests are of a remarkably mixed type. Flowering and non-flowering trees, palms and pines, tree ferns, shrubs and grasses all grow together in remarkable amity. Since Lithia never had a glacial period, these mixed forests, rather than the uniform type prevailing on Earth, are the rule. In general the vegetation is lush and the forests can be considered as typical rain-forests. There are several varieties of poisonous plants, including most of the edible-looking tubers. Their roots resemble potatoes and they produce extremely toxic alkaloids, whose structure has not yet been worked out, in large quantities. There are several types of bushes which grow thorns impregnated with glucosides which are extremely irritating to the skins of most vertebrates.