Stars are powered by nuclear fusion and the energy released radiates through their surface as heat. But all objects radiate away some form of electromagnetic radiation depending on their temperature.
Is it possible for a planet to be large enough (i.e. Have a large surface area to radiate away heat) and be hot enough (to increase the total energy emitted but NOT enough for it to visibly glow in the visible-light spectrum) to heat up a moon orbiting it to habitable temperatures?
And if so, at what distance would the moon have to orbit?
PS: You can assume the moon has an Earth-like atmosphere to moderate the temperature extremes and keep heat from radiating away like it does in our Moon.