Planetary Considerations

Abstract

We are assuming that life will only originate on a planet somewhat like our own. We will make some more specific assumptions later on in this section, particularly with regard to the presence of water. Even without such specific assumptions, a look at our own solar system, immediately gives an idea of what can go wrong with regard to the habitability of a planet, even if a planetary system is formed around a second generation star like our own: Mercury is too hot to sustain our kind of life, Venus has a crushing pressure, a very high temperature and a sulfuric acid atmosphere, Mars is very cold with an extremely dilute atmosphere. The rest of the planets (Jupiter, Saturn, Neptune, Uranus) have no solid surface at all , are at cryogenic temperatures and feature huge gravitational fields at their surfaces. Some of moons of Jupiter and Saturn are regarded as having some possibility of harboring life, though none has been found to date and they are all at least as inhospitable as Mars.