We have chosen three star systems to illustrate certain points. Two of them namely Epsilon Eridani and Cacri A could easily have a planet in the habitable zone or, in the of Cancri, a moon of a gas giant. However because of its young age Epsilon Eridani is unlikely to have yet developed any form of advanced life. We are of course assuming that the process of evolution is slow. Formalhaut as we can see has a very short life and life is hardly likely to gain a foothold on any planet within the theoretical habitable zone. In theory Cancri could already have developed advanced life by now or even a civilisation since it is about the same age of the Sun. In talking of star systems in general it should be remembered that the evidence now suggest because of the way that stars form all or nearly all will be surrounded by planets.