Yet no one ever saw an atom or a molecule. They are deemed to be proven because they are necessary. The sun is the apparent source of energy, and is confidently supposed by many to be a mass of burning material. No one, however, knows this to be so. No one was ever there, and the whole set of theories regarding the luminary rests on assumptions.
Many natural facts are against some of the theories.
The great fact that the higher the mountain the more cold it is on top would be one, not wholly accounted for by theories as to radiation. And when we remember the great, the immense, difference between the various scientific estimates of the sun's heat, doubt increases. Seeing that electricity is now so much better known, and that it is apparently all pervading, the ancient idea that the sun is a center of electrical or magnetic energy which turns into heat as well as other things on reaching here, becomes plausible and throws some spice of illusion into the doctrine that our sun is a mass of burning matter. Again, the sun is seen as if over the horizon in full view every clear evening, when in fact he has been some minutes down below the line of sight. Refraction partly accounts for his, but none the less is his apparent visibility or position above the horizon an illusion.