Go Brain!

If we plopped Jupiter in place of the moon, Earth will be outside the Roche Limit.

FuzzyGeff and I did the math in high school while we were developing worlds for my Traveller campaign at the time.  We wanted an earthlike world around a gas giant.

It's possible if you put your jovian just inside of Mars' orbit that way you're getting enough heat from the sun and the giant to keep water wet.

With the system design rules at the time, it was impossible to put a gas giant there.  Thanks to recent discoveries with exoplanets, we now know it's possible in the real world, to heck with the game's rules!

Aside: the spellchecker knows exoplanet but not earthlike.