> I propose that extraterrestrial civilizations may use free-floating planets as interstellar transportation to reach, explore and colonize planetary systems I

> I propose that extraterrestrial civilizations may use free-floating planets as interstellar transportation to reach, explore and colonize planetary systems If you can muster enough energy to accelerate a planet, you probably don't need a planet for migration in the first place. Also, the planets would get cold during the journey. Very cold. You'd better pack a load of welding kits for the brass monkeys.