Most of the Universe is uninhabitable. People keep talking about the "Goldilocks Zone" but that is just
one factor.
* We are on the outskirts of the Milky Way because the center of the galaxy is radiation hell. A chunk of most galaxies is too "hot" for life. So take most of the SPACE out there and move that to the side.
* The planet itself has to be around a star that's not too big and not too dim, at the right distance, of course.
* Our Solar system is very special as it has the planets in stable, almost circular orbits around a SINGLE star. It's not "collision central", where most planets can still smash into each other, within a binary star system, to boot.
* We have gas giants, by chance, protecting us against space rocks flying into us.
* The Moon, just the right size, just the right distance, to keep us in stable rotation, with seasons.
* Just the right amount of water. Too much or too little water, and we would not be here.
* I am probably missing a bunch...
* And only then you get to the rest of the factors for life to be possible.
* We are on the outskirts of the Milky Way because the center of the galaxy is radiation hell. A chunk of most galaxies is too "hot" for life. So take most of the SPACE out there and move that to the side.
* The planet itself has to be around a star that's not too big and not too dim, at the right distance, of course.
* Our Solar system is very special as it has the planets in stable, almost circular orbits around a SINGLE star. It's not "collision central", where most planets can still smash into each other, within a binary star system, to boot.
* We have gas giants, by chance, protecting us against space rocks flying into us.
* The Moon, just the right size, just the right distance, to keep us in stable rotation, with seasons.
* Just the right amount of water. Too much or too little water, and we would not be here.
* I am probably missing a bunch...
* And only then you get to the rest of the factors for life to be possible.