I also find it interesting that many believe there cannot be life on a planet such as Venus, with its seemingly harsh atmosphere. There are other types of life forms here on our very planet that live in harsh environments… such as the bacteria living in the highly acid environment of the stomach and the life around the boiling environment of the volcanic vents at the bottom of the sea. Creatures live in the deep parts of the ocean where the pressure is so strong it would crush most earthly life forms. They find tiny worms living in the frozen ice of glaciers. I think that life forms will appear in many of the places we now think unlikely.

@Michael Handley: Other species are the environment of a species too, it is unlikely that a diversified biosphere as ours would settle into stasis even if the rest of a species environment would. The best approximation would be early Earth, so prokaryotes would be forms compatible with stasis.

@June Ariola: That is pattern search, and it is futile here as everywhere else.

- There is in fact no correspondence between atoms and planets. The simplified atom model is not anything near the actual atom with its electron clouds, where there is a finite likelihood for electrons to appear _within_ the nucleus (except for the lowest energy spherical electron state).

- Stars in galaxies orbits overall (not counting clusters) a common center by way of the virial theorem. There does not need to be anything particular in the center, and in fact it seems our own Milky Way bar is not exactly centered on the mass center of its dark matter (the most massive component).

- Galaxy clusters emerges out of dark matter filaments from primordial fluctuations in the inflationary standard cosmology. It is too complicated trajectories to remind of the virial theorem as applied to an isolated galaxy. The filaments doesn’t merit the idea of nucleus, rather they look like embeddings of the visible matter.