Faint Sun Paradox - 2 of 3

For your consideration...the following is an excerpt from a radio spot on KAPL radio, Jacksonville, Oregon, called " Akin For the Truth". To listen to the entire spot (a few minutes long), click the little microphone icon....Jack

The general explanation for the independent creation of a star begins with incredibly large expanses of dust and gases, which congeal by gravity in the emptiness of space, heating up as it collects more and more material. This hot collection of material is called a protostar. When a protostar’s center reaches a high enough temperature for fusion to begin, then the star has theoretically joined the main sequence, the phase in which it will spend most of its life.

Supposedly the Sun has been a main-sequence star since its formation about 4.6 billion years ago. This time represents about half the assumed ten-billion-year main-sequence lifetime of the Sun, so the Sun should have used about half its energy store by now. This means that about half the hydrogen in the core of the Sun has been used up and replaced by helium. This necessitates that the Sun is nearly 40% brighter than it was 4.6 billion years ago, and a 40% change in solar luminosity would have produced dramatic climatic changes.