That is an amazing number of changes. I guess that would suggest that there are probably very few planets existing anywhere that have an atmosphere similar to earth’s.
“That is an amazing number of changes. I guess that would suggest that there are probably very few planets existing anywhere that have an atmosphere similar to earth’s.”
If aerobic life developed on only one planet per million stars, the Milky Way Galaxy in which we live would be home to hundreds of thousands of such planets with Oxygen loving aerobic life. Within the visible Universe among the other galaxies, there would be uncounted trillions of such planets.