> And in any case, current theory suggests that the sun will expand in the next few hundreds of millions of years making Earth uninhabitable to current life on

> And in any case, current theory suggests that the sun will expand in the next few hundreds of millions of years making Earth uninhabitable to current life on Earth. It's the brightening, more than the expansion, that'll do it. It'll ruin the carbonate/silicate cycle in a few hundred million years, progressively forcing plants into worse and worse metabolic pathways, so reducing the total energy available to the biosphere, until finally plant life is basically wiped out. IOW, 700-900MY from now, is the end of large fauna on planet Earth, followed soon after by the end of nearly all smaller fauna, too, and all or nearly all plants. Back to single-celled and very simple multi-cellular life, until most of that's killed a few hundred million years later, too, by the loss of all surface water. There will be little or no life left on Earth way before the sun significantly expands. Barring significant geo-engineering efforts.