I know this thread probably belongs to the ASB section, given that it's probably impossible. But still, I can't help but wonder, what if Jupiter had become a second sun? And because of the heat generated, this allowed for the prerequisites of a habitable Europa or Ganymede (those were one of the moons of Jupiter).
http://starryskies.com/articles/dln/1-02/jupiter.star.html Yeah, this website explained that even had Jupiter gained sufficient mass to become a sun, the resulting heat would probably have been too much and the planet (or sun) would have expanded and swallowed up its moons.
But let's assume that somehow, had Jupiter became a second sun; the heat it emitted would have been just enough to lead to a habitable Europa.
And while we're at it, what if Venus did not experience the runaway greenhouse effect that caused it to become the sulphuric hell-hole it is today? What if; instead, it was a tropical world with a breathable atmosphere with sufficient bodies of water for life? (Much like in that novel Stirling wrote)
What if Mars was habitable too? Just like in "A world of difference"?
What if the moons of Uranus or even Neptune also became habitable?
I'm not sure if such a thread has already been done (Been checking the forums and this idea seems novel enough). But, what would the implications be on humanity for a solar system that is "alive"? Now, this need not necessarily mean intelligent life but at the very least; flora and fauna.
I'd imagine a space race that would have been WAY hotter than the one in OTL of the 1950s to 70s between the USA and USSR. Possibly even colonies.
So, what do you guys think?