Yes! You have it figured out. We aren't able to go back in time or forward in time to see what it was like in the past or what it will be like in the future for the Sun. However, there are many stars in the sky, and each provides us with a snapshot of a particular stage of stellar evolution. By looking at all of them together we can determine how stars evolve in general. Then we just have to determine where our Sun fits in to the overall pattern, and this tells us what the future holds in store for it. You might be interested in this web page: http://www.astro.umd.edu/.../stev/evolution.html cheers, Sarah