In the future, should our Sun slowly burn out of fuel and supply us with sub-par sunlight, I have thought of a way to make Earth habitable. All we have to do is to redirect an increasing proportion of the Sun’s radiant heat to our planet at all times. This may sacrifice the other planets’ fair share of warmth, but since they’re uninhabited and since being hotter or colder wouldn’t significantly impact their orbits, this should only be a minor problem. Should there actually be aliens on Mars or Neptune, they’ll have to speak up.
The real major problem is how to have a gargantuan reflector (to suit our future red giant Sun) always reflecting excess rays towards us, given our planet is in continuous revolution and rotation? The answer lies in a material we’ve heard about for decades, carbon nanotubes. Although still outside our budget today, that should no longer be the case when the Sun starts to deplete. Future nanotubes will likely cost as much as today’s stainless steel. This nanotube chain will only physically tie with Earth’s and Sun’s magnetosphere, with simple connections to save on material costs.