fuadalami

So yesterday my buddies and I were watching a Neil deGrasse Tyson video and he was talking about space and how we've seen traces of life on other planets. As he talked about the planets he kept on referencing some sort of changing factor that tweaked the system which caused like to disappear from there. Thinking to myself what could be that factor? I concluded that over time as the sun continues to shrink, the exterior planets begin receiving smaller amounts of heat, eventually not enough to sustain life on the planet. Then planet by plant slowly we arrived at earth and our next planet to live on is not Mars but Venus. Are their any studies that say anything like that or can you guys point out any flaws in my thoughts?