ssj5harsh

I don't EXACTLY agree with what YT2095 has said. The reason simply is because the candle needs GASEOUS wax so that it can burn. On earth, Wax near the wick is heated, turns to liquid, then gaseous state. This gaseous wax burns. The wick serves the purpose of absorbing the liquid wax so that the gaseous wax can burn. In microgravity, the wax will not rise towards the flame and hence will burn out after some time. One way to check this is to notice that a vertical candle burns until the wick reaches the ground, but the same candle when held horizontally will burn out sooner and most of the candle will not be used.