Springer Online Journal Archives 1860-2000
Abstract The emergence of life based on amino acids and RNA/DNA on an Earth-type planet requires quite narrow ranges for many of the planet's physical parameters, most notably its mass and temperature conditions. In addition, only stars of F to K spectral types can have planets suitable for life, and only very favorable combinations of certain parameters can provide the necessary conditions for evolution into multicellular animals. A planet must have a mass about 5 · 1027 g; some zones with favorable thermal conditions (273-340 K); an atmosphere that is capable of absorbing hard external radiation but is transparent to photons with energies of 1-3 eV; a sufficient density of stellar radiation; the presence of other sources of energy, e.g., of oxidation species in the atmosphere; moderate gravitation; open water with big islands or continents; a moderate rotation period, orbital eccentricity, and inclination of the equatorial plane to the orbital plane; intensive meteoritic impacts or other cosmic catastrophes, which stimulate evolution of the most perfect beings; one or more massive satellites; and intensive volcanism and/or plate tectonics.
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