> planets can travel through space and have a protective shield - the atmosphere
Most worlds in our system don't have a significant atmosphere, most of those that do have too much of it. Like gravity, atmosphere also poses a problem for getting back to space.
> no man-made spaceship can match that for billions of years.
Not unmaintained, no, but if it was unmaintained that probably means everyone who lives there is dead anyway.
Most worlds in our system don't have a significant atmosphere, most of those that do have too much of it. Like gravity, atmosphere also poses a problem for getting back to space.
> no man-made spaceship can match that for billions of years.
Not unmaintained, no, but if it was unmaintained that probably means everyone who lives there is dead anyway.