chapter  10
46 Pages

Fundamentals of Solar Radiation ................................................................................... Contributing Author: Jan Kreider

Having been admonished by the Holy Office [the Inquisition] entirely to abandon the false option that the Sun was the center of the universe and immovable, and that the Earth was not the center of the same and that it moved … I abjure …

Galileo

The nature of energy generation in the sun is still an unanswered question. Spectral measurements have confirmed the presence of nearly all the known elements in the sun. However, 80% of the sun is hydrogen and 19% helium. Therefore, the remaining 100-plus observed elements make up only a tiny fraction of the composition of the sun. It is generally accepted that a hydrogen-to-helium thermonuclear reaction is the source of the sun’s energy. Yet because such a reaction has not been duplicated in the laboratory, it is unclear precisely what the reaction mechanism is, what role the turbulent flows in the sun play, and how solar prominences and sunspots are created.