This article speaks of the earth leaving our solar systems habitable zone in a billion years or so. I would like to propose a serious discussion of what we, as a species, can do about it. A billion years is a large amount of time, but the scope of the problem is also very large. One thought I had was to build large arrays of mirrors which would reflect sunlight back into space. The short term effect would be that less solar radiation is absorbed, thus cooling the planet. The long term effect would be that if we reflected the light in a rearward direction along our orbit, the force of the radiation pressure would gradually accelerate the planet into a higher orbit. I realize it would be very gradual, but we do have a billion years. There would be certain interesting problems to overcome as we approach the orbit of mars. Any thoughts on this idea, or any other ideas which might be more do-able?