Oh wow. That article is off in soo many ways
1: As I said, in 500MA the sun is predicted to be ~5% hotter / brighter than it is now, which is not a significant amount. It would barely be noticeable on earth due to quite a few factors, including orbital variations.
2: launching huge rockets will not move the earth for several reasons. First - physics, the rocket will push on the earth, and the earth will push back. Second - physics even if you could move the earth by rocket launches you would require so much fuel and materials that you would reduce the mass of the planet significantly, leading to a REDUCED orbit unless the planet was also significantly accelerated. Giant rockets PUSHING THE PLANET by ejecting mass into space might work, but again you would require so much mass that you would also have to accelerate the planet to move it to a stable orbit farther from Sol, which would wreak merry hell on crops and growing seasons... along with many other factors that would be extremely detrimental.
3: I won't get into the rest of the crazy crap that is not even remotely in the realm of reality.
4: The sheer amount of asteroids ETC. needed to move a planet is staggering. The rockets (or anything else really) used to move them would also, again, reduce the mass of the planet either leading to a closer orbit or the need for a significant amount of acceleration and all of the problems associated with that.
TL;DR version: The sun will not have a significant change to power output ( heat ) until near the time it hits the red giant branch. This is the time that it will greatly increase in both size and luminosity due to the Hydrogen shell ignition around the degenerate Helium core. The article you read was.... misinformed, to put it quite kindly. Utter crap to put it straight to the point.
Now I normally wouldn't link to a wikipedia article, but for once it is at least fairly well explained in the article about the stellar evolution of Sol
here up to and after it leaves the main sequence.