Part of the "Megastructures: The Visual Encyclopedia" book project, on sale now at http://www.neilblevins.com/megastructures/megastructures.htm
A Fusion Candle would be a giant engine that could potentially be used to move a gas giant planet to a new location. The engine would be placed deep inside the clouds of the gas giant. Intakes would inhale the gases (presumably hydrogen), funneling them to a giant fusion reactor, then light up the engine on both ends (a candle burning at both ends). One end would point toward the gas giant. The second would point out toward space. If kept in perfect balance, the end pointing toward the planet would keep the engine floating in the atmosphere, and the end pointing toward space would push the planet forward.