Could anyone give me a figure (in joules/kilo joules) for this? Wikipedia says (on it's gravitational binding energy page) that the gravitational binding energy of a star is equal to about two times it's internal thermal energy. I looked for "internal thermal energy" and could not find anything on it at all. I found figures for earth's gravitational binding energy, but not for the sun. There's a formula you can do to work it out, but my knowledge of maths is the layman's type, not the type with the "weird symbols" so I would have to have them explained to me.