Explanations for the Extreme Densities of Kerbol Worlds

[Pyre]

All the planets are Dyson shells surrounding a core of material from a neutron star. Same with the sun.

[Cesrate]

Just because the constants of physics are different from our universe. I think a more valuable question is how much are the values of physics constants to make tiny Kerbol burning for billions of years.

[Moon Goddess]

I considered changing the Strong force, but I think that will have disasterous effects on the sun's fusion.

[LordVe]

Be thankful that the Kerbol System isn't scaled properly. Were it, you would never be able to get to Jool. So far as I can see, the system is scaled at 10-1.5.

[tipsyMJT]

Stahp, what are you doing? Remember the last time we pointed out to the devs that something was impossible? Now we just have a memorial and something that holds 1/3rd the amount a Kerbals it used to. Mk1 cockpit: you were my friend.