Wolfbane - Frederik Pohl

This science fiction novel takes place in the year 2203, if we take literally the age of 250 years. A rogue planet, populated by strange machines known as Pyramids, has stolen the Earth from the Solar system, taking it off into interstellar space. The moon has been 'ignited' by alien technology to serve as a miniature sun around which both planets orbit. This new sun is rekindled every 5 years, though as the book opens, the rekindling is nearly overdue and there is fear among the populace that it may never happen again. - Summary by Wikipedia