“In principle, it would be possible for a super-technology to carry off an entire intact planet by manipulating the chaotic nature of some planetary orbits. Beginning with a nuclear explosion to deflect a small asteroid and bring it into collision with a larger body, a series of carefully controlled manoeuvres could have an accumulating and amplifying gravitational effect over an extended period. Eventually a planet’s orbit could be destabilized enough for it to be flung out of the planetary system altogether. Subsequent encounters with other stars would provide the opportunity for additional gravitational slingshot boosts to increase speed. The hijacked planet could then be used as a handy space ark for traversing the galaxy …. ”
–Paul Davies. The Eerie Silence: Renewing Our Search for Alien Intelligence. Boston: Houghton Mifflin Harcourt, 2010. Quote on page 135.