How Long Will the Sun Last, and What Does That Have To Do with Evolution?

These are questions that I was asked by email:

How long did evolution take?

3.5 billion years ago, there were bacteria on this earth. The earth is 4.5 billion years old. So life arose on earth in less than 1 billion years. No one knows how that happened, though scientists have some guesses. Nonetheless, whether it was by divine command, by DNA from other planets, or through the theories that scientists have, life did arise.

Generally, though, the origin of life is not considered part of the theory of evolution. The origin of life is abiogenesis.

By about 550 million years ago, many of the basic body forms that make up life were around. There were some very primitive fish, but no amphibians, no reptiles, no birds, and no mammals. Again, the path from the first bacteria to 550 million years ago is not well known.

From the Cambrian explosion, which happened about 540 million years ago, until now we have a pretty good understanding of what happened and a pretty good fossil record.

How much fuel is in the sun?

The sun is absolutely amazing! It consumes 600 million tons of hydrogen PER SECOND!!!

Nonetheless, even at that rate, it would take 70,000 years to consume the mass of earth. The sun, being much larger, has about 10 BILLION years of usable hydrogen in it. It's about halfway through that cycle, so we've got something over 5 billion years left.

Of course, even then it won't burn out. It will then start converting helium to carbon, which will cause it to expand, become a red giant, and destroy earth (5 billion years from now).

Is evolution possible based on how much fuel is/was in the sun?

Sure. Now, if DNA wandered here on meteoroids from another solar system, then perhaps abiogenesis needed a bit more time and began longer ago. Like I said, abiogenesis is still somewhat of an unknown.

However, over the last 3.5 billion years, yes, we can track how evolution occurred and at what rate it occurred.

When will the sun burn out or supernova?

Our sun is not big enough to supernova. When it gets through its red giant phase, it will collapse down into a white dwarf and last a few billion more years.

So, the sun will destroy life on the earth—and probably the earth as well—in 5 billion years, but it has several billion years after that to survive.

NASA has some great answers to questions about the sun on their web site.