But there's no maximum speed of light, so you could keep on accelerating forever. You can travel between galaxies. Even more, you can travel back home.
2226 BSB - Kerbals stop trying to wipe Gilly off the lenses of their telescopes, and discover it is actually a moon orbiting Eve. Glasses industry increases by 25000% as astronomers try to be the first to discover something about Gilly.
The same argument also applies to removing orbits, adding weapons and having unlimited fuel. Anyway, the knowledge system says 5 C, which can be explained by having tidal heating from Jool warm the surface.
Page 485 of this book has some more info: http://books.google.co.uk/books?id=Jpcz2UoXejgC&printsec=frontcover&dq=isbn:0816528446&hl=en&sa=X&ei=D0mjUdjUJpD30gX914CIAg&ved=0CDQQ6AEwAA#v=onepage&q&f=false
I've been playing since 14.4 and this is accurate I've got backups of every old version since .13, so I guess I could do a history of KSP video if I wanted to.