The Source of the Sun's Power

At the risk of being Captain Obvious, we get a heap of blessings from the sun. Living things depend on its energy for various reasons, we get warmth, time and seasons (Genesis 1:14-15), and other benefits. Without it, this planet would be a lifeless ball of ice hurtling through space. But you knew all that. Aside from thankful but deluded people who worship it, thoughtful folks have wondered what powers the sun.

There are two main theories for the sun's power, gravitational collapse and nuclear fusion. Neither justifies billions of years that secularists want.
The Sun, Edvard Munch, 1916
Is it powered by gravitational collapse? Nuclear fusion? A combination of both? In 1979, a couple of astronomers presented a paper where they thought they had evidence that the sun is indeed shrinking. Some creationists stampeded to present that idea because it fit with a younger universe paradigm, but secular and more cautious creationists realized that this idea should be filed under, "Don't go there, girlfriend". Still, where is the evidence for nuclear fusion? Why, neutrinos, of course. But why are only a third of the elusive little critters recorded? The alternate neutrino theory apparently took care of that problem.

So, we have the nuclear fusion idea, and this shows that the sun can last a few billion years. Secularists extrapolate backward and work solar evolution from the failed Big Bang concept, saying that the sun is billions of years old already. A problem with that idea is that projecting into the past is not justified; just because it's built to ride long and hard doesn't mean it's been doing that for a long time already. There's another problem: the sun is very stable, which is an indicator that it was created comparatively recently.
The 19th century saw the first scientific explanation for the sun’s energy. William Thomson (Lord Kelvin) and Hermann von Helmholtz proposed that the sun derived its energy from the conversion of gravitational potential energy. This process (now called the Kelvin-Helmholtz mechanism) would cause the sun slowly to shrink, but the shrinkage would be so gradual as to be virtually undetectable. The Kelvin-Helmholtz mechanism is a viable model, and astronomers think that all stars derive at least some of their energy from this mechanism at some stages. However, scientists generally rejected the Kelvin-Helmholtz model toward the end of the 19th century, because it could power the sun for “at most” 30 million years. At that time, many scientists were committed to gradual geological and biological evolution, processes that required much more time than the Kelvin-Helmholtz mechanism would allow.

If the conversion of gravitational potential energy does not power the sun, then what does? Early in the 20th century, astronomers began to suggest some sort of nuclear power source for the sun. Eventually, increased knowledge of nuclear physics revealed that the fusion of hydrogen into helium in the solar core is the most likely source of the sun’s energy. The sun contains abundant hydrogen for fuel, and from physics we know that the conditions in the solar core are sufficient to sustain the fusion of hydrogen into helium. If this is the source of the sun’s energy, it could power the sun for nearly 10 billion years.
To read the rest, click on "Is the Sun Shrinking?"