What Will Happen?

One of the things that has always fascinated me about public understanding of science is the question that somebody asks, and then immediately apologizes for asking a dumb question. Folks, there is NO such thing as a dumb question, but there are people who think they’ll LOOK dumb by asking something they think everybody but them knows the answer to.

One of those questions is “What’ll happen to the Sun?” Well, it’s a valid one. We’ve all heard that the Sun is about halfway through its life, that it’s about 4.5 billion years old. So, that suggests that in another five and a half billion years, something will happen. But what?

To tell you the truth, that’s a question we’ve been grappling with on this project I’m writing for. The current story is that the Sun will end its days as a white dwarf. Somewhere between now and that time, however, it might go through a giant phase and then a planetary nebula phase before it approaches white dwarfdom.

It’s a nice, orderly progression that satisfies our sense of science marching onward, but is it really going to happen? Maybe yes. Maybe no.

Not exactly what you want to know, is it? Well, science is like that. Based on the best available data, we try to give answers. When the data and models change, then the answers change. It doesn’t mean the original answer was wrong. It just means the data changed what we think is going to happen. If you give somebody directions down to the nearest shopping center or gas station and they come back and tell you that the stores are not there anymore, you weren’t wrong in your directions. You just didn’t know the truth of the matter.

So, what’s the truth of the matter when it comes to talking about the ultimate demise of our star? The current storyline could be written something like this: in about five billion or so years, the Sun will stop burning hydrogen in its core and start burning helium. The outer layers will expand with the added heat that is given off in the nuclear process, and the Sun may well become some sort of giant star. It may engulf Mercury. The orbits of Venus, Earth and possibly Mars could get shifted outward a bit. Then, after some amount of time, the outer atmosphere will blow off, and maybe (maybe!) there will be a planetary nebula surrounding the slowly shrinking (but still very hot) core of what’s left of the Sun. If there’s enough mass left over, the Sun will become a white dwarf.

That all sounds pretty iffy, but that’s the way it goes. Science aims to get us enough data to understand (and explain) these things. Right now the data point toward our Sun going through this set of steps in the far distant future. It’s a great story and I’d love to be around to see it happen!

However, keep in mind that some new data and observations could come in that will change this storyline—maybe subtly, maybe in a big way. That’s the way science works, too. And that is it’s greatest strength!