I am building a world that I would like to be as big as possible and still have very close to earth like conditions, gravity, weather, seasons, life and other things that are similar. Would things like massive underground caverns help increase the size and still be relatively stable? I am also planning on using the supernatural in this but want it to be based on as much science as possible.

  • $\begingroup$ Hi Zurrock, welcome to Worldbuilding! You may be interested in this question which asked solely about gravity. Full disclosure: I have the top-rated answer. Even though the ammonia one is actually better lol. $\endgroup$ – Dubukay Aug 29 '18 at 2:10
  • $\begingroup$ Hello Zurrock! The simple answer is that you can't have a planet any bigger or smaller than Earth and still have an Earth-like environment. Everything is so interconnected that it's easy to trip the balance. As @Dubukay points out, your biggest enemy is gravity. Bigger planet = higher gravity = thicker atmosphere, shorter plants, hotter environment, etc. etc. The idea of giant Earth-like planets is a sci-fi staple, but in reality, it doesn't work. You could get away with +/- 10%, maybe +/- 20%, but after that the chain of dependencies has nasty effects. This doesn't mean no life, though. $\endgroup$ – JBH Aug 29 '18 at 2:45