The right geography in stellar space is needed to create the correct ecology to allow the formation of earth-like planets:
Planet earth is a small planet of a typical G star at the edge of just one of the many billions of galaxies in a universe that is infinitely more vast than we can imagine. Our own galaxy contains some 300 billion stars and it may well be that there are approximately 100 billion galaxies in our observable universe. That would place the number of stars at approximately one billion trillion. Surely habitable planets could exist in such vast numbers even it they were as rare as one planet to every billion stars. As of yet we are unable to determine exactly how common is the formation of planets at the birth of a star let alone planets that will ultimately lead to habitability and therefore life. It is important therefore to discuss the formation of other possible solar system formations, explaining the preconditioned geography to create the ecology necessary to make a planet habitable like Earth.
