Rick65 wrote:
The sun involves fusion, not burning, with the fusion taking place in the core heating up the rest.
wiki
"In the inner portions of the Sun, nuclear fusion has modified the composition by converting hydrogen into helium, so the innermost portion of the Sun is now roughly 60% helium, with the metal abundance unchanged."
Yes, the sun involves fusion, not
combustion - but it is still "burning".
You are apparently limiting yourself and the verb "to burn" to refer to the process of combustion in particular, but that is not the only meaning of "burn".
http://oald8.oxfordlearnersdictionaries.com/dictionary/burn_1It can mean simply to be on fire or just to produce heat and/or flames. The fusion in the sun produces heat and what appears to be flames, therefore it is valid to say that it is burning. It is not valid to say that it is combusting, but it is consuming its fuel.
A "fuel" is said to "burn" if it is subjected to or engaged in a chemical (or nuclear) reaction which causes it to produce heat, light, or any other form of energy during which it is also consumed. Therefore it is valid to say that the hydrogen "fuel" in the sun is "burning" and by extension, the sun itself as well.
Nobody here said that the sun was combusting.
There are many other uses for and meanings of "to burn" as well. When your skin turns red after spending too much time outside on a clear and sunny day, it has been "burned" but there has been no combustion. That's one.