There are certain themes that arise in Astronomy Cast comments and fanmail. Most of the themes are happy, good, warm fuzzies. There are also your typical cranks. There are also, in the humorous category, a regular stream of well-meaning, highly hopeful people saying my mind isn’t open enough who accuse me of not talking to the right experts.
I actually laughed loudly enough to scare the dog when I read the following earlier today from here:
Please! Get your facts straight, people!
Your original assumption is faulty, the Sun does not need to heat up and expand in a billion years, it will not “run out of fuel” in a billion years.
The reason the Sun is predicted to heat up and expand in a billion years, is not lack of fuel, but the interference of the ash products, iron and silicon, with the internal fusion processes. There will still be 95 percent of the current amount of Hydrogen in the sun then, as there is now. Please talk to a knowledgeable Solar Physicist.
Removing those ash products so they will not interfere with the normal operation of the Sun, is merely an engineering problem.
Any person who uses a fireplace realizes that occasionally you need to remove the ash products.
Please talk to a knowledgeable Solar physicist before you go making simplistic unthinking fearmongering statements for the sake of entertainment. Yes, it is a danger. No, it is not an inevitability. Currently we don’t know how to fix it, but in 1910, we didn’t know how to make manned Moon landings, either. We know about the problem, we can work on the engineering solutions.
Let me say, it is not my habit to laugh out loud at comments. Nor is it my habit to share my dog scaring laughter publicly. This comment was posted publicly however, and I have to admit that the idea that we over hyped the eventual expansion of the Sun for the sake of entertainment is hilarious.
No, um, we weren’t fear mongering. Sorry.
So here’s the facts of physics. The Sun is a plasma gas. As it creates heavier elements, they fall to the center. Currently, in the center of the Sun there is a region that is of sufficient density and temperature thatÂ¬â€ hydrogen is fusing into helium. The helium, weighing more than hydrogen, has no desire to leave the core. When this region of burning is completely filled with helium, burning will stop, the Sun will collapse a bit, and a shell of hydrogen will end up burning around the core (causing the Sun to expand back out).
Now, in the above comment the idea is put forward that we should be able to clear this “ash”, the helium, out of the way to keep the Sun on the main sequence burning hydrogen. Let’s just disregard the fact that you can’t exactly fly a spacecraft into the center of a star even in the Star Trek universe. Ignoring the problem of building something that will function under pressures and temperatures that turn everything into plasma, my question is, move the helium to where? This is like saying you’re going to swim to the 10ft deep bottom of a swimming pool (that is undergoing nuclear reactions), and pick up all the rocks some little kid threw in and just leave them 3 feet up from the bottom of the pool. Yes, you can pick them up and hold them there, but when you let go, they kind of fall straight back down to the bottom. Now, in general I would tend to carry the rocks up from the bottom and just set them on the side of the pool, but the Sun doesn’t exactly have an edge and it seems very silly to remove the helium all together. This helium is a non-trivial amount of mass, and the energy requirements to move it (F=ma, and W=Fd, even in the future) are HUGE. If you have this kind of energy and technology, wouldn’t it be easier to just move Earth? (Which after all weighs less then all that helium). And if you’re tired of Earth, if you have that much energy, you can probably grab a few asteroids or a small moon, hollow them out, and make them a colony vessel that can just go somewhere else altogether.
I do firmly believe their is a bright technological future of unimaginable wonder in front of us. I also believe in particle physics and know that things (like space craft) tend to melt in the centers of stars. So… I vote for taking Earth to Alpha Centauri.