How Did Scientists Explain the Sun's Energy Before Nuclear Fusion?

[timman_24]

The history of our understanding of the sun is a very rich area. Ancients believed the sun was a god while we now know the sun is an enormous body of fusion. What I would like to discuss is how the scientists thought the sun worked after the development of the basics of thermodynamics but before the understanding of subatomic interactions. I believe between the years of 1800-1900's.

I'm sure there were many very fascinating theories, do any of you guys know some of these?

To get us started, Kelvin theorized the Sun was a large body of liquid that was slowly cooling by radiating its energy.

 

[Drakkith]

From a book I have, I remember them talking about thinking that the sun was a huge ball of something like Coal that was burning. But in the end, once the output of the sun was calculated, there was no way that coal could be putting out that much energy for anywhere near a long enough time.